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1
Blakley, Alivia. „Validity of Various Bioelectrical Impedance Analysis Devices vs the Bod Pod for Body Composition“. Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu155934084847866.
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2
Nescolarde, Selva Lexa. „Segmental and whole body electrical impedance measurements in dialysis patients“. Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6340.
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The main objective of this thesis is to contribute to the prevention and control of the cardiovascular risk, hydration state and nutritional state in dialysis patients using non-invasive electrical impedance measurements. The thesis is structured in three parts with the following objectives: 1) to establish electrical impedance reference data for healthy Cuban population, 2)to improve the diagnostic based on impedance methods in Cuban hemodialysis (HD)patients and 3) to develop the impedance methods for continuous ambulatory peritoneal dialysis patients (CAPD).Healthy population: We analyzed the impedance vector distribution using the Bioimpedance Vector Analysis (BIVA) for the three more representative race-ethnicities in Cuba. We measured 1196 healthy adult (689 M, 507 W, 18-70 yr). The 95% confidence ellipses were drawn using specific BIVA software for mean vectors of different races. Due to the close distribution of mean vectors that we found for the three race-ethnicities, we concluded that only one set of sex-specific tolerance ellipses can be used for the Cuban population.
HD patients: The BIVA method was used in a sample of 74 HD patients in stable (without edema) and critical (hyper-hydrated and malnutrition) states in order to establish the relation between hyper-hydration and mortality. Stable group include 48 patients (28 M and 18 W), and critical group include 28 critical patients (16 M and 12 W). Student's t test and Hotelling's T2 test were used to analyse the separation of groups obtained by means of clinical diagnosis and those obtained by BIVA. A statistically significant difference was obtained (P < 0.05) in R/H, Xc/H and phase angle, PA. Critical patients (hyper-hydrated and malnutrition) were located below the inferior pole of the 75% tolerance ellipse, with PA lower than 4º. In conclusion, the BIVA method could be used to detect hyper-hydration state before edema appears, and to predict survival through PA. Advantages of the method are its simplicity, objectivity and that it does not require the definition of a patient dry weight.
CAPD patients: Segmental impedance measurements were obtained using 9 configurations (7 longitudinal and 2 transversal) in 25 CAPD male patients.
In a first study we analyzed Z, Z/H and ZBMI indexes. 23 male patients were classified according to the hydration state as normo-hydrated, group 0 (10 M) or hyper-hydrated, group 1 (13 M). Wilcoxon test was used to analyze the change in impedance produced by a PD session. Mann-Whitney U test was used to analyse the separation between groups obtained by means of clinical diagnosis and those obtained by Z, Z/H or ZBMI. Spearman correlation was used to study the correlation between impedance vectors in each segment and clinical assessment. Statistical significance was set at P < 0.05. Results show that ZBMI gives information about the specific resistivity of tissues and not about fluid and fat mass changes. BIVA separate hyper-hydrated and normo-hydrated patients. Transversal measurements in the leg region and longitudinal in the thorax region are useful to corroborate the hydration and nutritional state in CAPD patients.
In a second study a new classification was performed. Group 0 has normo-hydrated patients (10 M) and group 1 includes patients (15 M) with varying degrees of hypertension, overhydration and high score on cardiovascular risk factors. Mann-Whitney U-test was used to compare the differences in clinical measurements, laboratory test, and bioimpedance measurements between groups. The Mahalanobis Distance (dM2) was calculated using a bidimensional space, using the resistance measurement, right-side (RRS/H) or thorax segment (RTH/H) and the BPmean. Hotelling's T2 test was used to analyzed difference between groups through (RTH/H, BPmean) and (RRS/H, BPmean) vectors. A statistically significant difference was obtained (P < 0.05) in both vectors. Group 1 showed a small dM2 with respect to a reference patient (a critical patient with acute lung oedema) with high BPmean and low values of RTH/H and RRS/H. Moreover, Group 0 showed a larger dM2 with respect to the reference patient with lower BPmean and higher values of RTH/H and RRS/H. All patients classified as hyper-hydrated leading to hypertension by clinical assessment were correctly classified using dM2(RTH/H, BPmean). We conclude that segmental bioimpedance of the thoracic region could be a simple, objective, non-invasive method of support to facilitate the clinical assessment in CAPD.
3
Fulton, William Sean. „Electrical impedance tomography applied to body-support interface pressure measurement“. Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336236.
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4
Shallof, Abulgasim M. „Multi-frequency electrical impedance tomography for medical diagnostic imaging“. Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265987.
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5
Montgomery, Sarah Lynn. „Impedance measurement system for embryonic stem cell and embryoid body cultures“. Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24661.
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6
Biver, Deborah J. „Analysis of body composition with use of body impedance analysis and skinfold calipers : a correlation study /“. View online, 1988. http://repository.eiu.edu/theses/docs/32211998878708.pdf.
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Company, Joe Ball Stephen D. „Body composition comparison bioelectric impedance analysis with DXA in adult athletes /“. Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/5697.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on September 16, 2009). Thesis advisor: Dr. Steve Ball. Includes bibliographical references.
8
Fallah, Shokr. „Application of bioelectrical impedance analysis to detect body composition of athletes“. Thesis, Queensland University of Technology, 2003.
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9
HOUTKOOPER, LINDA BRAUNSCHMIDT. „VALIDITY OF WHOLE-BODY BIOELECTRICAL IMPEDANCE ANALYSIS FOR BODY COMPOSITION ASSESSMENT IN NONOBESE AND OBESE CHILDREN AND YOUTH“. Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183914.
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Whole-body bioelectrical impedance analysis (BIA) was evaluated for its reliability and accuracy in estimating body composition in children and youth. The established electrical principle for estimating volume in a geometrical system from conductor-length('2) divided by impedance is the basis for the use of this method in humans. The hypothesis that body-height('2) divided by the resistance component of impedance (resistance index) can be used to estimate total body water (TBW), fat free body (FFB), and percent fat (%FAT) was tested. Validation studies in adults indicate BIA is a reliable and fairly accurate method of estimating TBW, FFB, and %FAT but no testing has been completed on children. The subjects were 103 nonobese and obese anglo males and females from 10 to 14 years old. Within-day reliability of resistance and reactance was assessed by analysis of variance with built-in comparisons. Between-day reliability for all measurements, made four to five weeks apart, was evaluated by test-retest correlation coefficients and paired t-tests. The criterion variables were FFB and %FAT estimated using equations developed for children and youth based on: (1) skinfolds, (2) body density, (3) TBW, (4) density and TBW, (5) density, TBW, and bone mineral content. Regression and multiple regression analyses were used to select the most accurate method of measuring FFB and %FAT and to determine the relationship among criterion variables and the following independent variables: resistance index alone and combined with sex, fatness category, sex x fatness, age, sexual maturation status, weight, anthropometric variables, and reactance. From this study the following conclusions were made: (1) BIA measurements were reliable, (2) resistance index had a linear relationship with FFB estimated from several criterion variables, (3) weight, sex, fatness category, sex x fatness, age, and sexual maturation status were significant variables for predicting criterion variables used in combination with resistance index but were not significant when anthropometric variables were included in the analysis, (4) prediction accuracy for FFB and %FAT from resistance index was fair (SEE 2.58 kg and 4.21%) and from resistance index plus anthropometric variables and reactance was good (SEE 1.88 kg and 3.26%) and similar to that from the best anthropometric variables alone (SEE 2.11 kg and 3.19%).
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Cornish, Bruce H. „Swept frequency biompedance analysis for the determination of body water compartments“. Thesis, Queensland University of Technology, 1994. https://eprints.qut.edu.au/37154/7/37154_Digitsed_Thesis.pdf.
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Bioelectrical impedance analysis, (BIA), is a method of body
composition analysis first investigated in 1962 which has recently received much attention by a number of research groups. The reasons for this recent interest are its advantages, (viz: inexpensive, non-invasive and portable) and also the increasing interest in the diagnostic value of body composition analysis. The concept utilised by BIA to predict body water volumes is the proportional relationship for a simple cylindrical conductor, (volume oc length2/resistance), which allows the volume to be predicted from the measured resistance and length. Most of the research to date has measured the body's resistance to the passage of a 50· kHz AC current to predict total
body water, (TBW). Several research groups have investigated the application of AC currents at lower frequencies, (eg 5 kHz), to predict extracellular water, (ECW). However all research to date using BIA to
predict body water volumes has used the impedance measured at a discrete frequency or frequencies. This thesis investigates the variation of impedance and phase of
biological systems over a range of frequencies and describes the development of a swept frequency bioimpedance meter which measures impedance and phase at 496 frequencies ranging from 4 kHz to 1 MHz. The impedance of any biological system varies with the frequency of the applied current. The graph of reactance vs resistance yields a circular arc with the resistance decreasing with increasing frequency and reactance increasing from zero to a
maximum then decreasing to zero. Computer programs were written to analyse the measured impedance spectrum and determine the impedance, Zc, at the characteristic frequency, (the frequency at which the reactance is a
maximum). The fitted locus of the measured data was extrapolated to determine the resistance, Ro, at zero frequency; a value that cannot be measured directly using surface electrodes. The explanation of the theoretical basis for selecting these impedance values (Zc and Ro), to predict TBW and ECW is presented. Studies were conducted on a group of normal healthy animals, (n=42), in which TBW and ECW were determined by the gold standard of isotope
dilution. The prediction quotients L2/Zc and L2/Ro, (L=length), yielded standard errors of 4.2% and 3.2% respectively, and were found to be significantly better than previously reported, empirically determined
prediction quotients derived from measurements at a single frequency. The prediction equations established in this group of normal healthy animals were applied to a group of animals with abnormally low fluid levels, (n=20), and
also to a group with an abnormal balance of extra-cellular to intracellular fluids, (n=20). In both cases the equations using L2/Zc and L2/Ro accurately and precisely predicted TBW and ECW. This demonstrated that the
technique developed using multiple frequency bioelectrical impedance analysis, (MFBIA), can accurately predict both TBW and ECW in both normal and abnormal animals, (with standard errors of the estimate of 6% and 3% for TBW and ECW respectively). Isotope dilution techniques were used to determine TBW and ECW in a group of 60 healthy human subjects, (male. and female, aged between 18 and 45). Whole body impedance measurements were recorded on each subject using the MFBIA technique and the correlations between body water volumes, (TBW and ECW), and heighe/impedance, (for all measured frequencies), were compared. The prediction quotients H2/Zc and H2/Ro, (H=height), again yielded the highest correlation with TBW and ECW respectively with corresponding standard errors of 5.2% and 10%. The
values of the correlation coefficients obtained in this study were very similar to those recently reported by others. It was also observed that in healthy human subjects the impedance measured at virtually any frequency yielded
correlations not significantly different from those obtained from the MFBIA quotients. This phenomenon has been reported by other research groups and emphasises the need to validate the technique by investigating its application
in one or more groups with abnormalities in fluid levels.
The clinical application of MFBIA was trialled and its capability of detecting lymphoedema, (an excess of extracellular fluid), was investigated. The MFBIA technique was demonstrated to be significantly more sensitive,
(P<.05), in detecting lymphoedema than the current technique of circumferential measurements. MFBIA was also shown to provide valuable information describing the changes in the quantity of muscle mass of the
patient during the course of the treatment. The determination of body composition, (viz TBW and ECW), by
MFBIA has been shown to be a significant improvement on previous bioelectrical impedance techniques. The merit of the MFBIA technique is evidenced in its accurate, precise and valid application in animal groups with a wide variation in body fluid volumes and balances. The multiple
frequency bioelectrical impedance analysis technique developed in this study provides accurate and precise estimates of body composition, (viz TBW and ECW), regardless of the individual's state of health.
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Bashara, Lisa Marie. „The effect of premenstrual edema on percent body fat measurements utilizing bioelectrical impedance“. Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/91161.
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The purpose of this investigation was to determine the effect of premenstrual edema (water retention) on measurements of percent body fat (%BF) in ovulating women during the menstrual cycle utilizing bioelectrical impedance. Specifically, this study was designed to investigate the difference between bioelectrical impedance measurements of %BF recorded during day 1 of menses, day 7, day -1 midcycle, midcycle, day 21, and days -3, -2, and -1 premenses. Determinations of impedance were made in 26 regularly menstruating women aged 20.23±0.74 yr using an electrical impedance analyzer with a four-electrode arrangement that induces a painless signal ( 800 !microamps at 50 kHz) into the body. Internal consistency reliability estimates made approximately 5 min apart during each test day ranged from R = .96-.99 for the impedance measurements of %BF, and the stability reliability correlation coefficients ever the eight observation days ranged from r = .92-.97 for the impedance measurements of %BF. The reliability analyses indicated that %BF esitimated from bioelectrical impedance was measured reliably. Specific days of the menstrual cycle did not significantly affect impedance measurements of %BF. Analysis of variance with repeated measures also indicated that day during the menstrual cycle did not significantly affect weight (Wt), %BF, resistance (Re), or total body water (TBW) measurements. However, urine osmolality (Osm) and basal body temperature (BBT) were significantly affected across days of the menstrual cycle (p < .01). A dramatic decline in Osm was noted at midcycle followed by a rise which peaked at day -3 premenses. After day -3 premenses, Osm rapidly declined at menses. The dramatic decline in Osm at midcycle may reflect changes in urine concentration due to actions of elevated estrogen associated with ovulation. BBT dropped prior to midcycle and then began to rise until day -3 of the next menses and then it dropped slightly. The drop prior -co midcycle may be also reflected by changes in the hormonal concentration of estrogen. The biphasic BBT response was considered to be presumptive evidence that ovulation had occurred. A 2 x 2 factorial analysis of variance with repeated measures demonstrated that there was a significant interaction between cycle length and activity level on measurements of Wt, %BF, and BBT (p < .05). As light activity subjects with average cycle lengths became moderately active, their %BF decreased from 26.51±0.63% to 21.11±0.50% followed by a dramatic increase to 29.40±0.62% as they became highly active. On the otherhand, as light activity subjects with above average cycle lengths became more and more active, their %BF dropped drastically from 35.11±1.44% to 18.72±0. 75%. The data support the hypothesis that bioelectrical impedance measurements of %BF recorded during the normal menstrual cycle are not significantly different. However, a larger population is required to validate the applicability of these results.M.S.
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Svedin, Frida. „Body composition during fasting and non-fasting conditions measured with bioelectrical impedance analysis“. Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-33920.
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Background: In 2014, there were nearly 2 billon overweight people around the world. This causes excessive costs for the society and is also a threat to the human condition. In recent time, there has been an increase of understanding the individual parts of the body composition. One method to measure body composition is using a bioelectrical impedance analyzer. The current recommendation is to measure during fasting conditions. However, there are few studies that have investigated a meal’s effect on body composition measured with bioelectrical impedance analysis, and those studies have presented varying results. If a bioelectrical impedance analyzer could be used without previous fasting, it would increase the use and utility of bioelectrical impedance analyzers. This could in turn, for example, reduce waiting lists in hospitals where bioelectrical impedance analyzers are used. Aim: The main aim of this study was to investigate a meal’s effect on body composition when measured with a bioelectrical impedance analyzer. The secondary aim was to investigate the correlation between skeletal muscle mass and hand grip strength when using a bioelectrical impedance analysis and a hand-held dynamometer respectively, during fasting conditions. Methods: In this present study, 27 subjects in the age of 21-59 years old participated. The subjects arrived at the laboratory in the morning during fasting conditions. Firstly, a bioelectrical impedance analyze and a hand grip strength test were completed. Thereafter, all subjects ate a meal containing at least 500 kcal. The following bioelectrical impedance analysis were completed 60, 90 and 120 minutes’ post meal intake. The data was then analyzed in SPSS version 20 through a paired T-test and a Pearson correlation test respectively. Results: The results showed that all body composition parameters investigated in this present study, except for minerals, not were statistically different 90 minutes after a meal intake containing at least 500 kcal, compared to the fasting condition, when measured with a bioelectrical impedance analyzer. Furthermore, a moderate correlation was found between hand grip strength and skeletal muscle mass for women. The same correlation was found weak for men. Conclusion: The results from this present study indicates that it is possible to measure body composition with a bioelectrical impedance analyzer 90 minutes’ post meal intake, except for minerals. Also, it indicates that a hand grip strength test is not a valid test for measuring skeletal muscle mass.
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Mooney, Angela. „Assessing Body Composition of Children and Adolescents using DEXA, Skinfolds, and Electrical Impedance“. Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3149.pdf.
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14
Grady, Patrick Alan. „Body mass index and percent body fat as determined by bioelectrical impedance analysis in children, 7-9 years of age“. Master's thesis, Mississippi State : Mississippi State University, 2006. http://library.msstate.edu/etd/show.asp?etd=etd-09112006-135145.
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15
Wei, Lin. „Predicting seat transmissibility from seat impedance and the apparent mass of the human body“. Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312865.
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Wotton, Marita J. „The application of bioimpedance analysis to monitor fluid losses and shifts associated with exercise“. Thesis, Queensland University of Technology, 1999.
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17
Duncan, Michael Bennett. „The use of bioelectrical impedance analysis for estimating the body composition of various fish species“. Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31531.
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The reliable measurement of growth and condition is vital for effective fisheries assessments. Biologists have long attempted to estimate condition for their assessments, but a reliable method to nonlethally estimate body composition is lacking. Proximate analysis is the most dependable and accurate method for estimating internal composition, but it is lethal, time consuming, and expensive. Recent research has shown bioelectrical impedance analysis (BIA) to be an effective method for estimating proximate composition in some fishes. The technique is quick, inexpensive, and, most importantly, nonlethal, which is vital when examining endangered species or cultured fish. My research focused on developing BIA indices for several new species of fish, using those indices to evaluate the body composition of fish in the field, and determining whether water temperature influenced resistance and reactance measurements. I found that BIA accurately estimated the body composition of bluegill Lepomis macrochirus, redear sunfish Lepomis microlophus, brook trout Salvelinus fontinalis, and northern logperch Percina caprodes (r2 â ¥ 0.71, p < 0.0001). I also determined that bluegill and redear regressions were not significantly different (P â ¥ 0.10) suggesting they can be used interchangeably during future studies. Laboratory studies revealed that water temperature did not significantly influence resistance and reactance measurements of bluegill, redear, and largemouth bass Micropterus salmoides (P â ¥ 0.18). These results, along with previous literature, indicate that BIA may be an accurate and reliable assessment tool for fisheries biologists.Master of Science
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Donnenwerth, Jesse James. „Validity of Bioimpedance as a Measure of Body Fat in High School Wrestlers“. Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28583.
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Background: In recent years several state high school athletic association have investigated methods to ensure the health and safety of high school wrestlers. One method implemented by the National Collegiate Athletic Association requires the prediction of minimum weight (MW) prior to the competition season. This weight certification program requires the assessment of body composition and hydration status. Results from those assessments place wrestlers in their lowest allowable wrestling weight class. There are a variety of measurement devises that have proven to be effective in measuring body composition. However, several considerations must be taken into account when choosing a devise such as affordability and reliability. Of those devices leg-to-leg bioelectrical impedance analysis (BIA) has been suggested for use with wrestlers.
Purpose: To test the validity of bioelectrical impedance as an instrument of body composition and minimum wrestling weight compared to three-site skinfold using the Lohman-Brozek formula and the Bod Pod®; among hydrated high school wrestlers.
Methods: Criterion for this study was the Bod Pod®. Subjects included 98 high school wrestlers taking part in the pre-season wrestling weight certification program implemented by the Virginia High School League. Hydration was assessed and a urine specific gravity (USG) ≤ 1.020 was assigned as the level of hydration.
Results: In order to investigate the validity of BIA in this study a repeated measure ANOVA with between-subjects factors was used to assess the equality of means between the three measurement devices. Also, in order to investigate hydration affect subjects were divided into two categories (hydrated and dehydrated). Finally, prior to analysis subjects were placed in weight categories based on their assigned wrestling weight class. Results of this study demonstrated that the three measurement devices did not produce similar results and it was concluded that hydration level had no affect on the measurements. Therefore, at this time BIA should not be considered as an alternative method for assessing body composition in high school wrestling weight certification programs.Ph. D.
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Jensen, Björn [Verfasser], Anja [Akademischer Betreuer] Bosy-Westphal und Claus-C. [Gutachter] Glüer. „Bioelectrical impedance analysis in the assessment of body composition – methodological considerations / Björn Jensen ; Gutachter: Claus-C. Glüer ; Betreuer: Anja Bosy-Westphal“. Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1211649288/34.
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Moody, Shoshanna Danielle McMurray Robert G. „The effect of menstrual cycle and submaximal exercise on acute body composition estimates from bioelectrical impedance“. Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1318.
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Thesis (M.A.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Apr. 25, 2008). "... in partial fulfillment of the requirements for the degree of Master of Arts in the Department of Exercise and Sport Science Exercise Physiology." Discipline: Exercise and Sports Science; Department/School: Exercise and Sport Science.
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Hastuti, Janatin. „Anthropometry and body composition of Indonesian adults : an evaluation of body image, eating behaviours, and physical activity“. Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61740/1/Janatin_Hastuti_Thesis.pdf.
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This thesis examines the characteristics of anthropometry and body composition in Indonesian adults and some of the risk factors including body image, eating behaviours, and physical activity. Examination on body image, eating behaviours, and physical activity demonstrates significant correlations with anthropometry and body composition in Indonesian adults. The study also identified body image distortion in some of the participants and provides suggestions for intervention development addressed to the groups of participants which have been identified as having a distorted body image.
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Marquez, Ruiz Juan Carlos. „Sensor-Based Garments that Enable the Use of Bioimpedance Technology : Towards PersonalizedHealthcare Monitoring“. Doctoral thesis, KTH, Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107493.
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Functional garments for physiological sensing purposes have been utilized in several disciplinesi.e. sports, firefighting, military and medical. In most of the cases textile electrodes (Textrodes)embedded in the garment are employed to monitor vital signs and other physiologicalmeasurements. Electrical Bioimpedance (EBI) is a non-invasive and effective technology that canbe used for detection and supervision of different health conditions. In some specific applicationssuch as body composition assessment EBIS has shown encouraging results proving good degreeof effectiveness and reliability. In a similar way Impedance Cardiography (ICG) is anothermodality of EBI primarily concerned with the determination of Stroke Volume SV, indices ofcontractility, and other aspects of hemodynamics.EBI technology in the previously mentioned modalities can benefit from a integration with agarment; however, a successful implementation of EBI technology depends on the goodperformance of textile electrodes. The main weakness of Textrodes is a deficient skin-electrodeinterface which produces a high degree of sensitivity to signal disturbances. This sensitivity canbe reduced with a suitable selection of the electrode material and an intelligent and ergonomicgarment design that ensures an effective skin-electrode contact area.This research work studies the performance of textile electrodes and garments for EBIspectroscopy for Total Body Assessment and Transthoracic Electrical Bioimpedance (TEB) forcardio monitoring. Their performance is analyzed based on impedance spectra, estimation ofparameters, influence of electrode polarization impedance Zep and quality of the signals using asreference Ag/AgCl electrodes. The study includes the analysis of some characteristics of thetextile electrodes such as conductive material, skin-electrode contact area size and fabricconstruction.The results obtained in this research work present evidence that textile garments with a dry skinelectrodeinterface like the ones used in research produce reliable EBI measurements in bothmodalities: BIS for Total Body Assessment and TEB for Impedance Cardiography. Textiletechnology, if successfully integrated, may enable the utilization of EBI in both modalities andconsequently implementing wearable applications for home and personal health monitoring.QC 20121213
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Fernando, Hamish Alexander. „Bioelectrical Impedance Analysis Scales for the Measurement of Body Composition in Research Environments and in the Real World: Can They Be Used Reliably?“ Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20822.
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Intermittent energy restriction has become a popular method for the management of obesity. It is however a very old concept, although not always used specifically for weight loss, a good example being the Ramadan fast. While the Ramadan fast has been shown to lead to weight loss, the assessment of body composition changes may be another important consideration. Chapter 2 therefore assesses the effect of the Ramadan fast on body composition via a systematic review and meta-analysis. This showed that the Ramadan fast caused a decrease in all parameters of body composition. Subgroup analyses showed a significant decrease in fat percentage only in people with overweight or obesity. In studies used for the above review on the Ramadan fast, various methods are used to track body composition, a clear majority of them using bioelectrical impedance scales. These scales are commonly used due to them being a cheap, quick and easy method. Their ubiquitous use makes it important to understand their reliability. It has been suggested that rate of weight loss could possibly influence the utility of the scales. In Chapter 3, this was addressed by comparing the body composition measurements obtained by the scales to the 4-compartment model (a gold-standard for body composition measurement), both before and after a diet plan involving either FAST or SLOW weight loss for 16 weeks. We found that for individuals, the scales were generally inaccurate and imprecise, especially after weight loss (regardless of rate). In groups, the scales were much more reliable, with comparisons of the means and standard deviations of the scales versus the 4-compartment model showing no significant difference across all analyses. These results highlight that bioelectrical impedance scales may not be ideal for measuring body composition in individuals, although they may be suitable for use in groups, for instance, in the case of the Ramadan studies utilized in Chapter 2.
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Montalvo, R., D. Kirwan, R. Gilman und Antonio Bernabe-Ortiz. „Bioimpedance markers and tuberculosis outcome among HIV-infected patients“. Obafemi Awolowo University, 2018. http://hdl.handle.net/10757/624732.
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ackground: The changes in body composition markers (weight, fat mass, lean mass, and BMI) over time can be associated with TB treatment outcome among HIV-infected patients. The aim of this study was to investigate whether changes in fat mass and lean mass were associated with the treatment response among patients with HIV infection and pulmonary tuberculosis. Materials and Methods: This was a prospective cohort study. Data from HIV-infected patients commencing TB therapy were analyzed. This included body weight measurement using bioimpedance equipment at baseline, one month, and two months after starting TB treatment. Results: The study was conducted in 125 patients, 17 patients (13.6%) died during treatment, of which 5 died during the first month of treatment, 4 during the second month and 8 after the second month. The group of patients with good response, increased their weight by 1.3 kg (p <0.001) at the end of the first month of TB treatment and 2.6 kg in the second month (p <0.001), and body fat increase was 1.2 Kg (p <0.001) and 2.3 kg (p <0.001), the first and second month respectively. The group of patients who died had lost 2.1 kg fat mass after the first month (p <0.001) and 3.7 kg in the second month (p <0.001). Conclusions: Our results show that the weight change during TB treatment (increased fat mass) helps us predict therapeutic response. Weight loss during the first month of starting therapy should be evaluated thoroughly to identify the probable cause of treatment failure.Revisión por pares
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Moshal, David Clive, und David Clive Moshal. „Single frequency whole-body impedance studies in children with diarrhoeal disease and development of a variable frequency system“. Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/24955.
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Diarrhoeal disease is a major cause of infant mortality in this and other developing countries. The assessment of the degree of dehydration in these children is often based on subjective findings alone. These have been shown to be inaccurate as an assessment of the degree of dehydration. Whole-body impedance (WBI) is a method of measuring total body water which is used to assess body composition. This WBI technology, which operates at a single frequency, has been applied to the assessment of dehydration in children with diarrhoeal disease. The normal range of WBI was determined on a group of normally hydrated children and was found to have a mean of 746 Ω, a standard deviation of 85 Ω and 95 % confidence interval for the mean from 720 Ω to 772 Ω. WBI did not depend on age, mass, height or sex. The WBI of a group of children dehydrated from infantile gastroenteritis was measured both before and after rehydration. The dehydrated group had a mean WBI on admission of 1089 Ω and a standard deviation of 149 Ω with a 95 % confidence interval for the mean from 950 Ω to 1109 Ω. This value was significantly greater than that of the normal group. The WBI of the dehydrated group after rehydration was not significantly different from the normal group. In addition a variable frequency bioimpedance analyser was designed and tested. It was found to have an error of less than 1 % over the frequency range 1 to 100 kHz. The device was evaluated on 11 normal and dehydrated children. Four dehydrated children were tested before and after rehydration and this data was compared to a standard electrical model for WBI. It was found that the model could represent the measured data over this frequency range. The extracellular resistive element of the model was mainly responsible for the changes seen during rehydration, suggesting that dehydration in gastroenteritis is mainly due to fluid loss from the ECF compartment.
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Hopkins, Michael Anthony. „Dynamic Locomotion and Whole-Body Control for Compliant Humanoids“. Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71808.
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With the ability to navigate natural and man-made environments and utilize standard human tools, humanoid robots have the potential to transform emergency response and disaster relief applications by serving as first responders in hazardous scenarios. Such applications will require major advances in humanoid control, enabling robots to traverse difficult, cluttered terrain with both speed and stability. To advance the state of the art, this dissertation presents a complete dynamic locomotion and whole-body control framework for compliant (torque-controlled) humanoids. We develop low-level, mid-level, and high-level controllers to enable low-impedance balancing and walking on compliant and uneven terrain.
For low-level control, we present a cascaded joint impedance controller for series elastic humanoids with parallel actuation. A distributed controller architecture is implemented using a dual-axis motor controller that computes desired actuator forces and motor currents using simple models of the joint mechanisms and series elastic actuators. An inner-loop force controller is developed using feedforward and PID control with a model-based disturbance observer, enabling naturally compliant behaviors with low joint impedance.
For mid-level control, we implement an optimization-based whole-body control strategy assuming a rigid body model of the robot. Joint torque setpoints are computed using an efficient quadratic program (QP) given desired joint accelerations, spatial accelerations, and momentum rates of change. Constraints on the centroidal dynamics, contact forces, and joint limits ensure admissibility of the optimized setpoints. Using this approach, we develop compliant standing and stepping behaviors based on simple feedback controllers.
For high-level control, we present a dynamic planning and control approach for humanoid locomotion using a novel time-varying extension of the Divergent Component of Motion (DCM). By varying the natural frequency of the DCM, we are able to achieve generic vertical center of mass (CoM) trajectories during walking. Complementary reverse-time integration and model predictive control (MPC) strategies are proposed to generate dynamically feasible DCM plans over a multi-step preview window, supporting locomotion on uneven terrain.
The proposed approach is validated through experimental results obtained using THOR, a 34 degree of freedom (DOF) series elastic humanoid. Rough terrain locomotion is demonstrated in simulation, and compliant locomotion and push recovery are demonstrated in hardware. We discuss practical considerations that led to a successful implementation on the THOR hardware platform and conclude with an application of the presented control framework for humanoid firefighting onboard the ex-USS Shadwell, a decommissioned Navy ship.Ph. D.
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Burkholder, William Joseph. „Body composition of dogs determined by carcass composition analysis, deuterium oxide dilution, subjective and objective morphometry, and bioelectrical impedance“. Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40419.
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Prediction of body composition was assessed in thirty-eight female and thirty-seven
male random source dogs using in vivo methods of deuterium oxide dilution, subjective and objective morphometry, bioelectrical impedance and ultrasound, either separately or in various combinations. Carcass composition determined by chemical analyses of carcass homogenates served as criterion measures of body composition. Dogs were selected based on gender, body weight and body condition score. Body weight ranged from 7.3 to 34.5 kilograms (kg), subdivided into 4.5 kg increments with 6 female and 6 male dogs per increment. Body condition was categorized as thin, optimum or obese using a defined criteria, body condition scoring system (subjective morphometry) with 12 female and 12 male dogs per body condition category. Selection criteria produced 18 body weight condition groups with 2 female and 2 male dogs per group. One additional male and 2 female dogs were included for economic and ethical reasons. Equations to predict carcass composition from in vivo measurements were derived using standard regression techniques. Influence diagnostics, residual analysis and data splitting were used to validate predicti ve equations. Predictions from deuterium oxide dilution produced the most precise estimates of body composition. Average standard errors of estimation (SEE) from deuterium equations were 1.3, 1.8, 1.0, and 0.4 percent for percentages of body moisture, fat, protein and ash, respectively, and 0.39, 0.57,0.21 and 0.08 kg for absolute quantities of moisture, fat, protein and ash, respectively. Morphometry produced the most imprecise, but economical, estimates. Average SEE from morphometry equations for proportions were 3.0, 4.0, 1.3, and 0.4 percent, and 0.9, 0.9, 0.3 and 0.07 kg for absolute quantities of moisture, fat, protein and ash, respectively. Subjective morphometry could estimate body fat with an average SEE of 3.4 percent and correctly categorized 75 percent of the dogs. Bioelectrical impedance and ultrasound produced predictions with average SEE intermediate to deuterium and morphometry. Bioelectrical impedance was equivalent to deuterium dilution on the basis of cost per unit improvement in SEE, but ultrasound was not cost effective.Ph. D.
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Mialich, Mirele Savegnago. „Proposta de novo Índice de Massa Corporal (IMC) corrigido por massa gorda através do uso da bioimpedância“. Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-02062010-144324/.
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A obesidade é definida como o excesso de tecido adiposo e tem sido demonstrada como deletéria para sistemas e órgãos. O IMC é um dos métodos mais utilizados para o diagnóstico de obesidade devido sua facilidade de aplicação e baixo custo. Entretanto, este índice possui a grande limitação de não diferenciar tecido adiposo de massa magra. Este trabalho buscou propor um novo escore para classificação do estado nutricional, embasado no IMC tradicional, porém ajustado pela massa gorda através do uso da bioimpedância em indivíduos de ambos os sexos. O estudo foi realizado com 200 indivíduos, de ambos os sexos, com faixa etária entre 18 e 60 anos e que estavam em acompanhamento no Hospital das Clínicas da FMRP USP. Os indivíduos foram divididos em: Grupo 1 (n=100) utilizado para construção do IMC corrigido e Grupo 2 (n=100), para aplicação do IMC corrigido e comparação com o IMC tradicional. Todos foram submetidos à avaliação antropométrica e de composição corporal. A amostra do Grupo 1 apresentou médias de idade de 49,6 ± 15,0 anos e 46,2 ± 17,6 anos; peso 71,7 Kg ± 18,5 e 64,6 Kg ± 16,0; estatura 169,6 cm ± 8,4 157,2 cm ± 5,8; IMC 24,8 ± 5,5 Kg/m2 e 26,1 ± 6,2 Kg/m2; massa magra , 51,1 Kg ± 9,9 e 38,6 Kg ± 5,8; massa gorda 23,4 % ± 8,3 e 35,3 % ± 9,, para homens mulheres, respectivamente. A amostra do Grupo 2 apresentou médias semelhantes para estas variáveis. Após a análise fatorial dos dados obtidos no Grupo 1, obteve-se um novo escore, sendo este (3 Peso + 4 MG) /Estatura. Considerando os pontos de corte para gordura corporal propostos pela WHO como, 25% e 35%, e até mesmo 20% e 30%, para homens e mulheres, respectivamente, verifica-se que este novo escore possui uma capacidade mais acurada de captar indivíduos obesos (0,953) em detrimento ao IMC tradicional (0,888), por este último não considerar os valores de MGT em seu cálculo. Em seguida, este mesmo escore foi aplicado em uma nova população, o Grupo 2 e os resultados superiores ao uso do IMC tradicional prevaleceram, sendo para o novo escore 0,986; 0,97 e 1 e para o IMC tradicional 0,978, 0,97, 0,98, ambos para todos os indivíduos, homens e mulheres, respectivamente. Além disso, este trabalho possibilitou a definição de novas faixas de pontos de corte do IMC para a classificação de obesidade, sendo estes nas faixas entre: 21,84 Kg/m2 a 26,11 Kg/m2; 22,03 Kg/ m2 a 25,3 Kg/ m2, para homens e mulheres, respectivamente, Estes nos permitem sugerir o uso de um novo IMC corrigido em detrimento ao IMC tradicional, como forma de suprir e possibilitar uma intervenção nutricional mais adequada. Portanto, este é o primeiro estudo brasileiro que além de questionar a validade do tradicional critério proposto pela WHO para obesidade e analisar a relação entre o IMC e o percentual de gordura, também propõe uma correção para o IMC e novos valores de IMC para classificação de obesidade.Obesity is defined as the excess adipose tissue and has been shown to have deleterious effects on organ systems. BMI is one of the methods used for the diagnosis of obesity due to its ease of application and low cost. However, this index has the great limitation of not differentiating fat-free mass. This study aimed to propose a new scoring system for classification of nutritional status, rooted in the traditional BMI, but adjusted for fat mass through the use of bioelectrical impedance in individuals of both sexes. The study was conducted with 200 individuals of both sexes, aged between 18 and 60, who were in attendance at the Hospital of FMRP - USP. The subjects were divided into Group 1 (n = 100) used for construction of BMI corrected and Group 2 (n = 100) for application of BMI and corrected BMI compared with the traditional. All underwent anthropometric measurements and body composition. The sample of Group 1 had a mean age of 49.6 ± 15.0 years and 46.2 ± 17.6 years, weight 71.7 ± 18.5 kg and 64.6 ± 16.0 kg, height 169, 6 cm ± 8.4 157.2 ± 5.8 cm, BMI 24.8 ± 5.5 kg/m2 and 26.1 ± 6.2 kg/m2, lean body mass, 51.1 ± 9.9 kg and 38.6 ± 5.8 kg, fat mass 23.4 ± 8.3% and 35.3% ± 9, for men women, respectively. The sample of Group 2 showed similar means for these variables. After the factor analysis of data obtained in Group 1, we obtained a new score, which is (3 + 4 Weight MG) / height. Considering the cut-off points for body fat as proposed by the WHO, 25% and 35%, and even 20% and 30% for men and women, respectively, it appears that this new scoring system has a capacity of more accurate capture individuals obese (0.953) rather than the traditional BMI (0.888), the latter does not consider the values of MGT in its calculation. Then, the same scoring system was applied to a new population, the Group 2 and the results than the use of traditional IMC prevailed, and the new score to 0.986, 0.97 and 1 for BMI and traditional 0.978, 0.97, 0.98, both for all individuals, men and women, respectively. In addition, this study allowed the definition of new cut-off points of BMI for the classification of obesity, which are among the bands: 21.84 kg/m2 to 26.11 kg/m2; 22.03 kg / m2 to 25.3 kg / m2 for men and women, respectively, these allow us to suggest the use of a new BMI corrected over the traditional BMI as a way to meet and allow a more appropriate nutritional intervention. So this is the first Brazilian study also question the validity of the traditional criterion proposed by WHO for obesity and examine the relationship between BMI and percent body fat, also suggests a fix for the new BMI and BMI classification for obesity .
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Castizo, Olier Jorge. „Bioelectrical impedance vector analysis (BIVA) in exercise and sports practice“. Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/666587.
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Bioelectrical impedance analysis (BIA) is a non-invasive technique widely used in body composition assessment. Nevertheless, its accuracy is compromised because of its reliance on regression equations and assumptions that are not frequently met. The bioelectrical impedance vector analysis (BIVA or "classic BIVA") emerged as an alternative technique to overcome conventional BIA limitations, founding its main strength on the use of raw impedance variables. BIVA is nowadays a widely used technique in medicine for the assessment of hydration and nutritional status in different clinical conditions. Although there has been a rapid growth of interest regarding the application of BIVA in sport and exercise research and practice in the recent years, the current scientific literature is still scarce and very heterogeneous. For this reason, we first systematically reviewed the current knowledge on the bases, applications, usefulness and suitability of BIVA in sport and exercise (Study I). Furthermore, we outlined future perspectives in this field and suggested a research agenda. In Studies II and III, we aimed at providing the first description, in bioelectrical terms, of a group of young elite female synchronised swimmers and a group of experienced, well-trained, non-professional, ultra-endurance male triathletes, comparing them with a reference non-athletic population. Additionally, we assessed the variation in the whole-body bioimpedance vector and body mass after a training session in synchronised swimmers and after a competition in triathletes. We concluded that the bioimpedance vector analysis is a technique that has a great potential in sport and exercise, yet largely unexplored, especially for the identification of soft-tissue injury and its follow-up. However, "classic" BIVA is inconsistent in the assessment of two-compartment body composition and the vector position of athletes in relation to the reference population seems controversial in many cases. "Specific" BIVA, a method which proposes a
correction of bioelectrical values for body geometry, seems to overcome this limitation . In any case, specific bioelectrical distributions were found in synchronised swimmers and triathletes in comparison with their healthy, general reference population. In relation with this, Study II reports for the first time specific tolerance ellipses in a female sport group. Furthermore, BIVA showed bioelectrical differences between synchronised swimmers of different age and performance level. Accordingly, Study III also reported bioelectrical differences between triathletes of different performance level. Regarding the assessment of hydration status through "classic" BIVA, this is not a valid method to identify dehydration in individual athletes. Nevertheless, vector changes are consistent with fluid loss induced by high intensity synchronised swimming training and by an ultra-endurance triathlon competition, regardless of age and performance level. Furthermore, vector changes seem consistent with fluid recovery 48h after the triathlon event. However, more research is needed regarding the relationship between the bioelectrical signal and physiological adaptations induced by different types of exercise, especially in how the structure and function of the cell are altered and how these affect the behaviour of resistance, and in particular reactance.El análisis de impedancia bioelectrica (BIA) es una técnica no invasiva ampliamente utilizada en la evaluación de la composición corporal. Sin embargo, su precisión se ve comprometida debido a la dependencia de ecuaciones de regresión y suposiciones que no se cumplen con frecuencia. El análisis del vector de impedancia bioeléctrica (BIVA o BIVA "clásico") surgió como una técnica alternativa para superar las limitaciones del BIA convencional, basando su principal fortaleza en el uso de parámetros primarios de impedancia. Hoy en día, BIVA es una técnica ampliamente utilizada en medicina como herramienta para la evaluación de la hidratación y el estado nutriciónal en diferentes condiciones clínicas. En cuanto a la aplicación de BIVA en la investigación y práctica de ejercicio y deporte, el interés ha crecido rápidamente en los últimos años, aunque la literatura científica actual es todavía escasa y muy heterogénea. Por esta razón, en la presente tesis realizamos primero una revisión sistemática sobre el conocimiento actual en relación a las bases, aplicaciones, utilidad e idoneidad de BIVA en el deporte y el ejercicio (Estudio I). Además, trazamos las perspectivas futuras en este campo y sugerimos una agenda de investigación. En los Estudios II y III, nuestro objetivo fue proporcionar la primera descripción, en términos bioelectricos, de un grupo de jóvenes deportistas de élite de natación sincronizada y un grupo masculino no profesional de triatletas de ultra-resistencia, experimentados y bien entrenados, comparándolos con su población sana de referencia. Además, evaluamos la variación en el vector de bioimpedancia de cuerpo completo y la masa corporal después de un entrenamiento en las nadadoras y después de competición en los triatletas. Tras analizar los resultados obtenidos, concluímos que el análisis del vector de bioimpedancia es una técnica que tiene un gran potencial (aún apenas explorado) en el deporte y el ejercicio, especialmente para la identificación de lesiones de tejidos blandos y su seguimiento a lo largo de la recuperación. Sin embargo, el BIVA "clásico" no es consistente en la evaluación bicompartimental de la composición corporal y la posición del vector de los atletas en relación a su población de referencia parece conflictiva en muchos casos. El BIVA "especffico", un metodo que propone una corrección de los valores bioelectricos en relación a la geometria del cuerpo, parece superar esta limitación. En cualquier caso, se encontraron distribuciónes bioeléctricas especificas en nadadoras de natación sincronizada y en triatletas en comparación con su población sana de referencia. En relación a esto, el Estudio II genera por primera vez elipses de tolerancia específica en un grupo femenino de deportistas. Ademas, BIVA mostró diferencias bioeléctricas entre las nadadoras de diferentes edades y niveles de rendimiento. Asimismo, el Estudio III tambien informó sobre diferencias bioeléctricas entre los triatletas de diferentes nivel deportivo. Con respecto a la evaluación del estado de hidratación a través del BIVA "clasico", éste no es un método valido para identificar la deshidratación en atletas. Sin embargo, los cambios en el vector son consistentes con la pérdida de fluidos inducidos por un entrenamiento de natación sincronizada de alta intensidad y por una competición de triatlón de ultra-resistencia, independientemente de la edad y el nivel de rendimiento deportivo. Además, la migración del vector parece consistente con la recuperación de Iíquidos 48 horas despues de la carrera de triatlón. Sin embargo, se necesita investigar más acerca de la relación entre la señal bioeléctrica y las adaptaciones fisiológicas inducidas por diferentes tipos de ejercicio, especialmente en cómo son alteradas la estructura y la función celular, y cómo estas afectan al comportamiento de la resistencia y, en particular, al de la reactancia.
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Liparulo, Timothy L. „The effects of varying hydration conditions on the estimation of body composition by bioelectrical impedance analysis, near infrared interactance, and dual-energy x-ray absorptiometry“. Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1217378.
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The purpose of this study was to examine the effects of hydration status on the prediction of body composition using BIA, NIR, and DEXA. Twenty healthy males and females ages 18 to 28 were recruited for this study. The subjects were dehydrated in the climate control chamber and engaged in physical exercise, until they lost approximately 1%, 2%, and 3% of their pre-exercise body weight. Percent body fat (%BF), body weight, and urinalysis measures were taken initially on day 1, on day 4 at euhydration, following 1%, 2%, and 3% dehydration, and upon rehydration during day 5. The results indicated that there were significant decreases for %BFBIA and %BFNIR between euhydration and 1%, 2%, and 3% dehydration. %BFDExA did not significantly change.There were also significant differences in the response to dehydration between each technique. Proper hydration should be ensured before %BF is estimated with BIA and NIR.School of Physical Education
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Inglis, J. Greig. „Are Bioelectrical Impedance and Skinfolds Considered Valid Measures for Tracking Body Composition Following Resistance Training when DEXA is the Criterion Measure?“ Digital Commons @ East Tennessee State University, 2001. https://dc.etsu.edu/etd/124.
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The present study was designed to determine if BIA and skinfolds could track changes in body composition like DEXA. Fifty male volunteers participated in a 12-week high-intensity resistance-training program. Body composition was assessed using DEXA, skinfolds (SF), and BIA. Results indicate when DEXA was used as the criterion measure; BIA and SF may not be appropriate assessment techniques. BIA and SF significantly overestimated percent fat and fat-weight pre- and post-treatment (p<0.05). Although SF and BIA exhibited acceptable r-values, significant differences were observed between DEXA and BIA and SF (p < 0.0001). These results indicate that DEXA’s ability to track changes in body composition may be more appropriate compared to BIA and SF during and following a resistance-training program. Future studies using hydrostatic weighing are needed to determine if differences observed are the results of DEXA’s accuracy in tracking fat free-weight or the inability of BIA and skinfolds to track changes.
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Dietrich, Alexander Markus [Verfasser], Alin [Akademischer Betreuer] Albu-Schäffer und Boris [Akademischer Betreuer] Lohmann. „Whole-Body Impedance Control of Wheeled Humanoid Robots / Alexander Markus Dietrich. Betreuer: Alin Albu-Schäffer. Gutachter: Alin Albu-Schäffer ; Boris Lohmann“. München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1079001751/34.
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Dietrich, Alexander [Verfasser], Alin [Akademischer Betreuer] Albu-Schäffer und Boris [Akademischer Betreuer] Lohmann. „Whole-Body Impedance Control of Wheeled Humanoid Robots / Alexander Markus Dietrich. Betreuer: Alin Albu-Schäffer. Gutachter: Alin Albu-Schäffer ; Boris Lohmann“. München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1079001751/34.
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Inglis, J. Greig. „Are bioelectrical impedance and skinfolds considered valid measures for tracking body composition following resistance training when DEXA is the criterion measure?“ [Johnson City, Tenn. : East Tennessee State University], 2000. http://etd-submit.etsu.edu/etd/theses/available/etd-0720101-095739/restricted/inglisg0726.pdf.
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Bello, Gabriela Brenner. „Avaliação da composição corporal pela bioimpedância e pelas dobras cutâneas em pacientes com diabetes tipo 2 : um estudo de acurácia diagnóstica“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/106730.
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Introdução: A medida do percentual de gordura corporal (PGC) sofre a influência de diversos fatores (obesidade severa, acúmulo excessivo de gordura no abdomen, hidratação, etc), dependendo da técnica utilizada, podendo comprometer o desempenho das mesmas. Muitos destes fatores estão frequentemente presentes nos pacientes com DM tipo 2, o que torna essencial o estudo da acurácia destes métodos nesta população. Objetivo: Avaliar a Bioimpedância (BIA) e as Dobras Cutâneas (DC) como métodos de estimativa da gordura corporal em pacientes com DM tipo 2, comparando-os com a Absorciometria de Raios X de Dupla Energia (DXA), como método de referência. Métodos: Neste estudo de acurácia diagnóstica, os pacientes foram submetidos à avaliação da composição corporal através da BIA (InBody 230, Biospace, Coréia), das DC (Lange, Fórmulas de Petroski e de Durnin) e da DXA (Lunar - iDXA). Para avaliação clínica foram analisados o controle metabólico (glicêmico e perfil lipídico) e pressórico e pesquisadas as complicações crônicas do DM. Resultados. Foram avaliados 133 pacientes (76 mulheres; idade: 63,6 ± 9,1 anos, duração do DM: 15,5 ± 10,3 anos; IMC: 29,2 ± 3,6), sendo que o PGC médio foi de 42,4 ± 4,8% nas mulheres e 31,1 ± 4,7% nos homens (p<0,001). A correlação do PGC estimado pela BIA e pelas DC com o estimado pela DXA foi, respectivamente r=0,93 (p<0,001) e r=0,81 (p<0,001). A BIA subestimou o PGC em 1,4 ± 3,2 (p<0,05) nas mulheres e 2,3 ± 3,3% (p<0,05) nos homens, quando comparada a DXA, sendo estas diferenças menos acentuadas nos pacientes com IMC≥ 30 kg/m2 (Gráficos de Bland-Altman). As DC subestimaram o PGC quando calculado com a Fórmula de Petroski, (3,7 ± 4,0% [p<0,05] nas mulheres e 1,55 ± 3,8% [p<0,05] nos homens) e superestimaram quando calculado com a Fórmula de Durnin ajustada para a idade, sendo que este ultimo apenas nas mulheres (1,8 ± 4,5% [p<0,05]). Na análise das curvas ROC, a área sob a curva da BIA foi 0,945 nas mulheres e 0,897 nos homens. Para as DC, utilizando as diferentes fórmulas, as áreas sob a curva variaram de 0,611 a 0,673 nas mulheres e foram 0,960 nos homens. Conclusão: Para a avaliação da composição corporal de pacientes com DM tipo 2, tanto a BIA como as DC (dependendo da fórmula) subestimam o PGC, comparados a DXA, mas em valores não clinicamente relevantes. A BIA apresentou uma boa acurácia em ambos sexos. Já a medida pelas DC mostrou acurácia semelhante, mas apenas nos homens.Objective. To evaluate the performance of bioimpedance (BIA) and skinfold thickness as methods to estimate percentage body fat (PBF) in patients with Type 2 diabetes, comparing them to Dual Energy X-Ray Absorptiometry (DXA), as a reference standard. Research Design and Methods. In this study of diagnostic accuracy, the patients were submitted to evaluation of body composition with BIA (InBody 230, Biospace, Korea), skinfold thickness (Lange caliper) and DXA (Lunar - iDXA). PBF estimated by skinfold thickness was calculated with three equations: Petroski, Durnin & Womersley (DW) gender-adjusted and DW age-adjusted. Clinical evaluation consisted of the metabolic (glycemic and lipid profile) and blood pressure control, as well as the search for diabetic chronic complications. Results. One hundred and thirty-three patients were evaluated (76 women; age: 63.6 ± 9.1 years, duration of diabetes: 15.5 ± 10.3 years; body mass index [BMI]: 29.2 ± 3.6 kg/m2). PBF estimated by DXA was 42.4 ± 4.8% in women and 31.1 ± 4.7% in men (p<0.001). The correlation of the PBF estimated by BIA and by skinfold thickness with that estimated by DXA was, respectively, 0.93 (p<0.001) and 0.81 (p<0.001). BIA underestimated the PBF at 1.4 ± 3.2 (p<0.05) in women and 2.3 ± 3.3% (p<0.05) in men, compared to DXA, and these differences were less pronounced in patients with BMI ≥ 30 kg/m2 (Bland-Altman Plots). PBF calculated by Petroski’s equations was underestimated in 3.7 ± 4.0% [p<0,05] in women and 1.55 ± 3.8% [p<0.05] in men; and overestimated in 1.8 ± 4.5% [p<0.05] when calculated using DW equations age-adjusted only in women. The area under the ROC curves for BIA as a method to identify patients with increased PBF was 0.945 (p<0.001) in women and 0.897 (p<0.001) in men. The area under the ROC curves for skinfold thickness varied from 0.611 to 0.673 (all p>0.05) in women and was 0.960 (all P<0,05) in men. Conclusion. In patients with type 2 diabetes, both BIA and skinfold thickness underestimated PBF, when compared to DXA, at values that ranged from 1.4 to 2.3% and 1.5 to 4.5%, respectively. BIA was accurate in both sexes as a method to estimate PBF and to identify patients with increased PBF. On the other hand, PBF estimated by skinfold thickness was similarly accurate, but only in males.
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STEPINSKI, JOY DIANA. „OBJECTIVE AND SUBJECTIVE MEASUREMENTS OF NORMAL AND OVER HYDRATION“. University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990804483.
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Newsome, Shaun. „Body Mass Index as a Parameter to Evaluate the Prevalence of Hypertension in NH White, NH Black, and Hispanic Americans“. Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/iph_theses/226.
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Over the past 30 years, obesity has been primarily identified by the body mass index (BMI). Due to its ease of calculation, the BMI has become the most widely used diagnostic tool to identify weight problems. This study examined the association between hypertension and BMI in White, Black, and Hispanics in the United States. The study’s hypothesis was that this relationship was weaker in Blacks than in the other groups. Data for the study came from the 2007-2008 and 2009-2010 National Health and Nutrition Examination Surveys. The association was weaker in Black men than in Whites or Hispanics on a univariate basis, and at most BMI levels on a multivariate basis. For females, it was also weaker in Blacks at most BMI levels on a univariate basis. However, multivariate logistic regression analysis did not indicate that the hypothesis held for Black women when adding covariates to the models.
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Dahlem, DeAnna Kay. „RELATIONSHIP BETWEEN PERCENT BODY FAT AS DETERMINED BY BIOELECTRICAL IMPEDANCE ANALYSIS AND WAIST-TO-HIP RATIO IN CHILDREN AGES 7 TO 9 YEARS“. MSSTATE, 2006. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06022006-222016/.
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The objective of the study was to identify the relationship between percent body fat (%BF) and waist-to-hip ratio (WHR) in children ages 7 to 9 years. The sample (n=171) was divided into four groups. Bioelectrical impedance analysis was used to estimate %BF. Significant positive correlations were observed between WHR and %BF for black females (r = 0.48), white females (r = 0.66), black males (r = 0.34), and white males (r = 0.55). Although the correlations differed between groups, the amount of variation between the two variables was not significantly different between groups other than black females. Least squares means was used to estimate %BF using an average WHR (.85). Black females had higher %BF than other groups. Percent body fat cannot be fully explained by WHR (r2 = 0.32). Results show a relationship between %BF and WHR, yet predicting %BF from a given WHR may be difficult.
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Duncan, Scott. „Physical activity and obesity in children measurement, associations, and recommendations : a thesis submitted to the Auckland University of Technology in fulfilment of the degree of Doctor of Philosophy, 2007“. Click here to access this resource online, 2007. http://hdl.handle.net/10292/429.
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Widespread increases in the prevalence of childhood obesity have raised the prospect of serious public health consequences in many countries. New Zealand is no exception; according to the most recent national estimates, approximately one in three children is overweight or obese. As a consequence, an understanding of the specific risk factors that predict this condition in children is becoming increasingly important. It is generally accepted that the promotion of physical activity is a key strategy for reducing the risk of childhood obesity. However, there is limited information describing physical activity and its relationship with body fatness in young New Zealanders. The overall aim of this thesis was to gain insight into the associations between excess fatness and physical activity in New Zealand children from a diverse range of socio-demographic groups. Three related studies were conducted to achieve this aim: a large descriptive survey of obesity and physical activity patterns in primary-aged children, and two preceding studies which develop the methodology for objective assessment of physical activity in this population. The first study provided the only validation data for the NL-2000 multiday memory (MDM) pedometer in children. In a sample of 85 participants aged 5-7 and 9-11 years, the NL-2000 offered similar accuracy and better precision than the widely used SW-200 pedometer (NL-2000: mean bias = -8.5 ± 13.3%; SW-200: mean bias = -8.6 ± 14.7%). The second study investigated reactivity to wearing pedometers over four 24-hour testing periods in 62 children aged 5-11 years. The sample was divided into two groups: one was given a full explanation of the function of the pedometer, while the other received no information prior to testing. The absence of significant differences in step counts between the first and last test periods indicated that there was no evidence of reactivity to this device for either preparation procedure. The central study presented in this thesis was the measurement of physical activity, body composition, and dietary patterns in 1,226 children aged 5-12 years, from which four chapters (4-7) were derived. The sample was ethnically diverse, with 46.8% European, 33.1% Polynesian, 15.9% Asian, and 4.1% from other ethnicities. Physical activity levels over three weekdays and two weekend days were assessed using NL 2000 pedometers. Percentage body fat (%BF) was determined using hand-to-foot bioelectrical impedance analysis with a prediction equation previously developed for New Zealand children. Waist and hip girths, height, and weight were measured using standard anthropometric techniques. Parent proxy questionnaires were used to assess demographic and lifestyle factors and pedometer compliance. The first reported analyses of this dataset (Chapter 4) examined the effect of weather conditions on children’s activity levels. In boys, a 10ºC rise in ambient temperature was associated with a 10.5% increase in weekday steps and a 26.4% increase in weekend steps. Equivalent temperature changes affected girls’ step counts on weekdays only (16.2% increase). Precipitation also had a substantial impact, with decreases in weekday and weekend step counts during moderate rainfall ranging from 8.3% to 16.3% across all sex, age, and socioeconomic (SES) groups. The aim of Chapter 5 was to understand the relationship between children’s step counts and their body mass index (BMI), waist circumference (WC), and %BF. Mean step counts for this sample were 16,133 ± 3,864 (boys) and 14,124 ± 3,286 (girls) on weekdays, and 12,702 ± 5,048 (boys) and 11,158 ± 4,309 (girls) on weekends. Significant associations were detected between steps.day-1 and both WC and %BF, but not between steps.day-1 and BMI. The findings in Chapter 6 extended these results by estimating the number of steps required to reduce the risk of excess adiposity in children (16,000 and 13,000 steps.day-1 for boys and girls, respectively). Finally, the study described in Chapter 7 examined the associations between excess adiposity and a series of demographic and lifestyle variables, providing the first assessment of body fat correlates in young New Zealanders. Our results indicated that children aged 11-12 years were 15.4 times more likely to be overfat (boys, %BF ≥ 25%; girls, %BF ≥ 30%) than those aged 5-6 years. In addition, the odds of overfat were 1.8 times greater in Asian children than in European children, and 2.7 times greater in the low SES group when compared with the high SES group. Three modifiable behaviours related to fat status were also identified: low physical activity, skipping breakfast, and insufficient sleep on weekdays. Clustering of these risk factors resulted in a cumulative increase in the prevalence of overfat.
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Islam, Naimul. „The potential for using combined electrical impedance and ultrasound measurements for the non-invasive determination of temperature in deep body tumours during mild hyperthermia“. Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56721/.
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The effectiveness of mild hyperthermia in improving the outcome of radiotherapy and chemotherapy treatment is well established for surface tumours (e.g. an average improvement of 20% in the 5 years survival rate using mild hyperthermia in conjunction with radiotherapy). However, to apply this technique to deep body solid tumours clinically, a non-invasive thermometry method is needed. Several approaches have been proposed for non-invasive thermometry in the past but none were capable of providing 3D temperature distributions in-vivo with the required accuracy. In this thesis, the potential for determining the temperature in a deep body solid tumour during mild hyperthermia by combining ultrasound propagation velocity and electrical impedance measurement techniques has been investigated. Simultaneous ultrasound propagation velocity and electrical impedance measurements were made in-vitro on liver, fat and layered fat-liver samples as the temperature was increased to mild hyperthermia levels (45°C max.). From the ultrasound measurements a linear correlation was found between the percentage of fat in the sample and the change in ultrasound propagation velocity with temperature (-0.12ms-1°C-1%-1, r2 = 0.93). Analysis of the data from the multi-frequency electrical impedance measurements showed that the magnitude of the electrical impedance measured at 256kHz normalised to the magnitude of the electrical impedance measured at 8kHz gave a linear correlation with the percentage of fat in the sample (0.003 %-1, r2 = 0.72) but no statistically significant correlation between the fat content and the temperature coefficient at 256kHz (r2 = 0.007, p >0.05). These results support an approach of using high to low frequency impedance ratios to determine the percentage of fat in the tissue and then this together with an ultrasound propagation velocity measure to detect the change in the temperature of the tissue. Application of this technique is limited by the variation in the change in ultrasound propagation velocity with temperature between tissue samples found in this study but the origins of this are unclear. In addition, further improvements in the spatial sensitivity of the tetrapolar impedance measurements are necessary to ensure an adequate spatial determination of fat content.
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COVA, ILARIA. „NUTRITIONAL STATUS AND BODY COMPOSITION BY BIOELECTRICAL IMPEDANCE VECTOR ANALYSIS: A CROSS-SECTIONAL AND LONGITUDINAL STUDY IN MILD COGNITIVE IMPAIRMENT AND ALZHEIMER¿S DEMENTIA“. Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/545028.
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Aim To analyze nutritional status and body composition in Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI) with respect to elderly healthy controls (HC), in order to find any biomarker of disease.
Methods A cross-sectional and a longitudinal study was performed in a memory clinic of a University-Hospital, by recruiting patients with mild-moderate AD, subjects with MCI and HC. Nutritional status was assessed at baseline for all the subjects and repeated at follow-up in AD patients by anthropometric parameters (body mass index; calf, upper arm and waist circumferences), Mini Nutritional Assessment (MNA) and body composition by bioelectrical impedance vector analysis (BIVA). For the cross-sectional study variables were analyzed by analysis of variance and subjects were grouped by cognitive status and gender; for the cross-sectional study in AD variables were analyzed by dependent t-test for repeated measures and linear regression analysis within gender. MCI were follow-up by repetition of neuropsychological tests to detect a potential progression to dementia and AD. MCI subjects’ characteristics at baseline were compared by outcome using non-parametric statistics.
Results Sociodemographic variables did not differ among the three groups (59 mild AD, 34 MCI and 58 HC), except for females’ age, which was therefore used as covariate in a general linear multivariate model. MNA score was significantly lower in AD patients than in HC; MCI subjects achieved intermediate scores. AD patients (both sexes) had significantly (p<0.05) higher height-normalized impedance values and lower phase angles (body cell mass) compared with HC; a higher ratio of impedance to height was found in men with MCI with respect to HC. With BIVA method, MCI subjects showed a significant displacement on the RXc graph on the right side indicating lower soft tissues (Hotelling’s T2 test: men=10.6; women=7.9;p < 0,05) just like AD patients (Hotelling’s T2 test: men=18.2; women=16.9; p<0,001).
After 8.7 ± 3.6 months of follow-up, bioelectrical variables of 40 AD patients did not significantly change. Forty-three MCI (28 females, 15 males) were followed up for 14.4 ± 8.6 months; 8 (6 females, 2 males) of them progressed to AD. Due to the limited number of males progressed, only females MCI’s bioelectrical characteristics were analyzed and those who progressed to clinically evident AD showed lower phase angles than stable MCI with considerable trend toward significance (5.9 1.0 vs. 5.2 0.6, p 0.069).
Conclusion Bioelectrical parameters significantly differ from MCI and AD to HC, but remain stable after approximately 9 months of AD patients’ follow-up; MCI who progressed to clinically evident AD had a lower PA which approached the borderline of significance. Analysis of body composition with BIVA could detect early changes in body composition which may perhaps reflect early systemic manifestation of the AD process at MCI stage of disease, before anthropometric change becomes evident. Increasing the cohort of MCI and their longitudinal observation will provide further information to understand if a BIVA pattern indicating a worse nutritional status could be an early and sensitive marker of progression to dementia or specifically to AD in MCI subjects.
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Grecco, Mirele Savegnago Mialich. „Validação de Índice de Massa Corporal (IMC) ajustado pela massa gorda obtido por impedância bioelétrica“. Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-13072012-143709/.
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A obesidade é definida como o excesso de tecido adiposo e o IMC tem sido um dos métodos mais utilizados para o diagnóstico de obesidade devido sua facilidade de aplicação e baixo custo. Entretanto, este índice possui a grande limitação de não diferenciar tecido adiposo e massa livre de gordura. Este trabalho buscou validar o Índice de Massa Corporal ajustado pela massa gorda obtido por impedância bioelétrica previamente desenvolvido por Mialich et al., 2011. Foi realizado um estudo transversal com 501 indivíduos, de ambos os gêneros, com faixa etária entre 17 e 38 anos, matriculados em cursos de graduação da USP do campus de Ribeirão Preto. Os indivíduos foram submetidos à aferição de peso, estatura e a avaliação de composição corporal através do equipamento de impedância bioelétrica. Além disso, foram coletadas informações referentes ao padrão alimentar por meio da aplicação de um questionário desenvolvido pelos pesquisadores, e também referente à prática de atividade física através da utilização do questionário IPAQ. A participação dos alunos foi voluntária e todos os indivíduos foram avaliados somente 1 vez no estudo e por um grupo de examinadores treinados. Para validação foi utilizado o modelo de regressão linear, sendo o IMC ajustado a variável independente e o IMC tradicional a variável dependente. A amostra era composta por 366 mulheres e 135 homens e apresentou médias de idade de 20,8 ± 3,2 anos e 20,3 ± 2,7 anos; peso 76,9 Kg ± 13,6 e 57,8 Kg ± 9,2; estatura 177,3 cm ± 6,7 e 163,1 cm ± 6,3; IMC 24,4 ± 3,8 Kg/m2 e 21,7 ± 3,0 Kg/m2; massa livre de gordura, 60,0 Kg ± 7,7 e 39,8 Kg ± 3,8; massa gorda 17,0 % ± 6,2 e 26,6 % ± 6,2, para homens e mulheres, respectivamente. Com relação à validação foram verificados valores elevados e satisfatórios de R2 sendo, 91,1%, 91,9% e 88,8%, considerando todos os indivíduos, homens e mulheres, respectivamente. Foram definidas também novas faixas de classificação do estado nutricional para ambos os gêneros, considerando este novo IMC ajustado, sendo: 1,35 a 1,65 (risco nutricional para subnutrição), > 1,65 e 2,0 (eutrofia) e > 2,0 (obesidade). Verificou-se também que este novo índice possui uma capacidade mais acurada de captar indivíduos obesos (0,980; 0,993; 0,974), considerando todos os indivíduos, mulheres e homens, respectivamente, e os pontos de corte para gordura corporal de 25% (homens) e 35% (mulheres), em detrimento ao IMC tradicional (0,932; 0,956; 0,95). Além disso, este trabalho possibilitou a definição de novos de pontos de corte do IMC tradicional para a classificação de obesidade, sendo: 25,24 Kg/m2 e 28,38 Kg/m2, para mulheres e homens, respectivamente. O novo IMC ajustado foi validado para a população estudada e pode ser adotado na prática clínica. Novos estudos devem buscar a sua aplicação em diferentes etnias assim como a comparação deste índice com outros já descritos previamente na literatura científica.Obesity is defined as the excess fat and BMI has been one of the most widely used methods for the diagnosis of obesity because of its ease of application and low cost. However, this index has a major limitation of not differentiating adipose tissue and fat- free mass. This study aimed to validate the Body Mass Index adjusted for fat mass obtained by bioelectrical impedance analysis previously developed by Mialich et al., 2011. We conducted a cross-sectional study with 501 subjects of both genders, aged between 17 and 38 years, enrolled in graduate courses at the USP campus at Ribeirao Preto. The subjects underwent measurement of weight, height and body composition assessment by bioelectrical impedance analysis. In addition, information was collected regarding the eating pattern by applying a questionnaire develops by the researchers, and also on the physical activity questionnaire using the IPAQ. The student participation was voluntary and all subjects were evaluated only one time in the study and by a group of trained examiners. For validation we used the linear regression model, being the BMI-adjusted the independent variable and BMI-traditional the dependent variable. The sample consisted of 366 women and 135 men and it had a mean age of 20.8 ± 3.2 years and 20.3 ± 2.7 years, weight 76.9 ± 13.6 kg and 57.8 ± 9.2 kg, height 177.3 ± 6.7 cm and 163.1 ± 6.3 cm, BMI 24.4 ± 3.8 kg/m2 and 21.7 ± 3.0 kg/m2, fat-free mass, 60.0 ± 7.7 kg and 39.8 ± 3.8 kg, fat mass 17.0 ± 6.2% and 26.6 ± 6.2% for men and women, respectively. With respect to validation were found high and satisfactory R2 values, 91.1%, 91.9% and 88.8%, considering all individuals, men and women, respectively. We also defined new range classification of nutritional status for both genders, considering this new BMI, as follows: 1.35 to 1.65 (nutritional risk for malnutrition), > 1.65 and 2.0 (normal) and > 2.0 (obesity). It was also found that this new index has the capacity to capture more accurate obese subjects (0.980, 0.993, 0.974) whereas all individuals, men and women, respectively, and the cutoff points for body fat of 25% (men) and 35% (women), rather than the traditional BMI (0.932, 0.956, 0.95). Moreover, this study allowed the definition of new points to traditional BMI cutoff for the classification of obesity, and: 25.24 kg/m2 and 28.38 kg/m2 for women and men, respectively. The new BMI set was validated for the population studied and may be adopted in clinical practice. Further studies should seek their implementation in different ethnic groups as well as the comparison of this index with other previously described in the literature.
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Toffano, Roseli Borges Donegá. „Análise vetorial de impedância bioelétrica e ângulo de fase em lactentes de 30 a 90 dias de idade a termo, adequados para a idade gestacional“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/17/17144/tde-28052018-174249/.
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Devido às dificuldades encontradas excessivas variabilidades de água no organismo do lactente, considera-se a análise vetorial de impedância bioelétrica (BIVA) um método propício para avaliação da composição corporal. Trata-se de um método que não faz nenhuma pressuposição sobre valores da composição corporal, podendo ser controlado por seus próprios valores, independente de equações ou modelos. Os objetivos deste estudo foram descrever valores de referência e criar curvas de BIVA para lactentes saudáveis de 30 a 90 dias de vida e descrever valores de normalidade de ângulo de fase em lactentes a termo, sadios e adequados para a idade gestacional de 30 a 90 dias de idade, além de comparar os dados de BIVA entre os sexos e entre os existentes na literatura para neonatos e lactentes jovens, com os obtidos neste estudo. Este estudo descritivo transversal avaliou 150 lactentes do Centro Médico Social Comunitário Vila Lobato de Ribeirão Preto - SP - Brasil. Foram coletados dos lactentes os dados antropométricos e a impedância bioelétrica (aparelho de monofrequência RJL System ® modelo Quantum II - 800 ?A e 50 KHz). Usando distribuição bivariável normal de resistência e reactância por comprimento (R/H e Xc/H) do lactente, respectivamente, foram calculados e assim confeccionados os gráficos RXc com os intervalos de tolerância de 95, 75, 50% do valor vetorial da impedância por meio do BIVA Software 2002. Foram avaliados 150 lactentes (48,6% do sexo feminino), nascidos a termo, adequados para idade gestacional e em aleitamento materno exclusivo. A idade média foi 56,4 (± 23,1) dias. O peso médio encontrado foi de 5038,5g (± 902,4), sendo maior no sexo masculino (p = 0,001). Quanto ao comprimento corporal, a média foi 56,0 cm (± 0,03), sendo maior no sexo masculino (p = 0,001). As médias de R (±DP) foram 521,2 (± 52,1); 519,4 (± 53,4) e 523,0 (± 51,1) ?, e para Xc foram 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectivamente para todos os lactentes, e separados por sexo (meninos e meninas), não havendo diferença entre os sexos (p = 0,6) e (p = 0,1). Em relação ao ângulo de fase, encontrou-se o valor de normalidade de 4,3° (± 0,7°) para todos os lactentes, 4,3° (± 0,6°) para os do sexo masculino e 4,4° (± 0,5°) para os do sexo feminino, não havendo diferença estatisticamente significativa (p = 0,3). Para a análise vetorial de lactentes de 30 a 90 dias de idade, devem ser utilizados os valores de referência específicos para esta faixa etária e sexo, pois estes se apresentaram diferentes dos descritos na literatura. Com o modelo de estudo BIVA torna-se possível a comparação direta do vetor medido na criança pequena ou com necessidade de cuidados especiais com os intervalos de tolerância de referência de lactentes saudáveis, permitindo uma avaliação qualitativa da composição corporal e sem erro de predição das fórmulas. Com os valores de ângulo de fase caracterizados no presente estudo para lactentes brasileiros saudáveis, de 30 a 90 dias de idade, dados de pacientes críticos podem ser comparados, sendo útil durante a internação e acompanhamento de pacientes graves.Bioelectrical impedance vectorial analysis (BIVA) can be considered a favorable method for evaluation of the body composition, due to the difficulties in the early life and excessive variability of the amount of water in the organism of the infants. It is a method that doesn\'t make any presumption on values of the body composition, which can be controlled by their own values, with no need for validation based on gold standards, not depending on equations or models. The aims of the study are to establish reference values creating BIVA curves, and to establish reference values for phase angle in term infants, healthy and appropriate-forgestational age (AGA), from 30 to 90 days of life. This study still intend to compare the data of BIVA between genders, among newborns and young infants, presented in the literature, and the ones obtained in this study. This transversal cohort study assessed healthy infants of a Community Centre for Social Medicine Vila Lobato, located in Ribeirão Preto, São Paulo, Brazil. Data of infants, anthropometry and bioelectrical impedance were collected (singlefrequency - RJL System ® model Quantum II - 800 ?A and 50 KHz). Using bivariate normal distribution of R/H and Xc/H (resistance and reactance for infants length, respectively), graphs RXc with the 95, 75 and 50% tolerance intervals of the vectorial value of the impedance, were made through BIVA Software 2002. 150 infants were studied (48,6% girls), term, AGA, exclusively breastfed. The average age was 56,4 (± 23,1) days, average weight was 5038,5g, higher in girls (p = 0,001), and the average length was 56,0 cm (± 0,03), higher in girls (p = 0,001). The values of R (± SD) were 521,2 (± 52,1); 519,4 (± 53,4) and 523,0 (± 51,1) ? and for Xc were 39,2 (± 5,3); 38,6 (± 5,5) e 39,7 (± 4,9) ?, respectively for all the infants, and boys and girls, with no difference between the genders (p = 0,6) and (p = 0,1). Regarding to the phase angle, we found normal value of 4,3° (± 0,7°) for all the infants, 4,3° (± 0,6°) for male and 4,4° (± 0,5°) for female, without statistical difference (p = 0,36). For Bioelectrical Impedance Vector analysis of infants from 30 to 90 days of life, it would be interesting to use specific reference values for this age group and gender. BIVA model makes possible the direct comparison of the measured vector of the small children; still makes it possible for children needing special care, using the tolerance reference values of healthy infants. This comparison allows us a qualitative assessment of the body composition, with no need of equations. With the values of phase angle characterized in the present study for healthy Brazilian infants, from 30 to 90 days of life, critical patients data can be compared, being useful during the hospitalization due to severe illness.
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Liu, Ailing. „Body composition and its relationship to metabolic risk factors in Asian children“. Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/47432/1/Ailing_Liu_Thesis.pdf.
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Obesity is a major public health problem in both developed and developing countries. The body mass index (BMI) is the most common index used to define obesity. The universal application of the same BMI classification across different ethnic groups is being challenged due to the inability of the index to differentiate fat mass (FM) and fat�]free mass (FFM) and the recognized ethnic differences in body composition. A better understanding of the body composition of Asian children from different backgrounds would help to better understand the obesity�]related health risks of people in this region. Moreover, the limitations of the BMI underscore the necessity to use where possible, more accurate measures of body fat assessment in research and clinical settings in addition to BMI, particularly in relation to the monitoring of prevention and treatment efforts. The aim of the first study was to determine the ethnic difference in the relationship between BMI and percent body fat (%BF) in pre�]pubertal Asian children from China, Lebanon, Malaysia, the Philippines, and Thailand. A total of 1039 children aged 8�]10 y were recruited using a non�]random purposive sampling approach aiming to encompass a wide BMI range from the five countries. Percent body fat (%BF) was determined using the deuterium dilution technique to quantify total body water (TBW) and subsequently derive proportions of FM and FFM. The study highlighted the sex and ethnic differences between BMI and %BF in Asian children from different countries. Girls had approximately 4.0% higher %BF compared with boys at a given BMI. Filipino boys tended to have a lower %BF than their Chinese, Lebanese, Malay and Thai counterparts at the same age and BMI level (corrected mean %BF was 25.7�}0.8%, 27.4�}0.4%, 27.1�}0.6%, 27.7�}0.5%, 28.1�}0.5% for Filipino, Chinese, Lebanese, Malay and Thai boys, respectively), although they differed significantly from Thai and Malay boys. Thai girls had approximately 2.0% higher %BF values than Chinese, Lebanese, Filipino and Malay counterparts (however no significant difference was seen among the four ethnic groups) at a given BMI (corrected mean %BF was 31.1�}0.5%, 28.6�}0.4%, 29.2�}0.6%, 29.5�}0.6%, 29.5�}0.5% for Thai, Chinese, Lebanese, Malay and Filipino girls, respectively). However, the ethnic difference in BMI�]%BF relationship varied by BMI. Compared with Caucasians, Asian children had a BMI 3�]6 units lower for a given %BF. More than one third of obese Asian children in the study were not identified using the WHO classification and more than half were not identified using the International Obesity Task Force (IOTF) classification. However, use of the Chinese classification increased the sensitivity by 19.7%, 18.1%, 2.3%, 2.3%, and 11.3% for Chinese, Lebanese, Malay, Filipino and Thai girls, respectively. A further aim of the first study was to determine the ethnic difference in body fat distribution in pre�]pubertal Asian children from China, Lebanon, Malaysia, and Thailand. The skin fold thicknesses, height, weight, waist circumference (WC) and total adiposity (as determined by deuterium dilution technique) of 922 children from the four countries was assessed. Chinese boys and girls had a similar trunk�]to�]extremity skin fold thickness ratio to Thai counterparts and both groups had higher ratios than the Malays and Lebanese at a given total FM. At a given BMI, both Chinese and Thai boys and girls had a higher WC than Malays and Lebanese (corrected mean WC was 68.1�}0.2 cm, 67.8�}0.3 cm, 65.8�}0.4 cm, 64.1�}0.3 cm for Chinese, Thai, Lebanese and Malay boys, respectively; 64.2�}0.2 cm, 65.0�}0.3 cm, 62.9�}0.4 cm, 60.6�}0.3 cm for Chinese, Thai, Lebanese and Malay girls, respectively). Chinese boys and girls had lower trunk fat adjusted subscapular/suprailiac skinfold ratio compared with Lebanese and Malay counterparts. The second study aimed to develop and cross�]validate bioelectrical impedance analysis (BIA) prediction equations of TBW and FFM for Asian pre�]pubertal children from China, Lebanon, Malaysia, the Philippines, and Thailand. Data on height, weight, age, gender, resistance and reactance measured by BIA were collected from 948 Asian children (492 boys and 456 girls) aged 8�]10 y from the five countries. The deuterium dilution technique was used as the criterion method for the estimation of TBW and FFM. The BIA equations were developed from the validation group (630 children randomly selected from the total sample) using stepwise multiple regression analysis and cross�]validated in a separate group (318 children) using the Bland�]Altman approach. Age, gender and ethnicity influenced the relationship between the resistance index (RI = height2/resistance), TBW and FFM. The BIA prediction equation for the estimation of TBW was: TBW (kg) = 0.231�~Height2 (cm)/resistance (ƒ¶) + 0.066�~Height (cm) + 0.188�~Weight (kg) + 0.128�~Age (yr) + 0.500�~Sex (male=1, female=0) . 0.316�~Ethnicity (Thai ethnicity=1, others=0) �] 4.574, and for the estimation of FFM: FFM (kg) = 0.299�~Height2 (cm)/resistance (ƒ¶) + 0.086�~Height (cm) + 0.245�~Weight (kg) + 0.260�~Age (yr) + 0.901�~Sex (male=1, female=0) �] 0.415�~Ethnicity (Thai ethnicity=1, others=0) �] 6.952. The R2 was 88.0% (root mean square error, RSME = 1.3 kg), 88.3% (RSME = 1.7 kg) for TBW and FFM equation, respectively. No significant difference between measured and predicted TBW and between measured and predicted FFM for the whole cross�]validation sample was found (bias = �]0.1�}1.4 kg, pure error = 1.4�}2.0 kg for TBW and bias = �]0.2�}1.9 kg, pure error = 1.8�}2.6 kg for FFM). However, the prediction equation for estimation of TBW/FFM tended to overestimate TBW/FFM at lower levels while underestimate at higher levels of TBW/FFM. Accuracy of the general equation for TBW and FFM compared favorably with both BMI�]specific and ethnic�]specific equations. There were significant differences between predicted TBW and FFM from external BIA equations derived from Caucasian populations and measured values in Asian children. There were three specific aims of the third study. The first was to explore the relationship between obesity and metabolic syndrome and abnormalities in Chinese children. A total of 608 boys and 800 girls aged 6�]12 y were recruited from four cities in China. Three definitions of pediatric metabolic syndrome and abnormalities were used, including the International Diabetes Federation (IDF) and National Cholesterol Education Program (NCEP) definition for adults modified by Cook et al. and de Ferranti et al. The prevalence of metabolic syndrome varied with different definitions, was highest using the de Ferranti definition (5.4%, 24.6% and 42.0%, respectively for normal�]weight, overweight and obese children), followed by the Cook definition (1.5%, 8.1%, and 25.1%, respectively), and the IDF definition (0.5%, 1.8% and 8.3%, respectively). Overweight and obese children had a higher risk of developing the metabolic syndrome compared to normal�]weight children (odds ratio varied with different definitions from 3.958 to 6.866 for overweight children, and 12.640�]26.007 for obese children). Overweight and obesity also increased the risk of developing metabolic abnormalities. Central obesity and high triglycerides (TG) were the most common while hyperglycemia was the least frequent in Chinese children regardless of different definitions. The second purpose was to determine the best obesity index for the prediction of cardiovascular (CV) risk factor clustering across a 2�]y follow�]up among BMI, %BF, WC and waist�]to�]height ratio (WHtR) in Chinese children. Height, weight, WC, %BF as determined by BIA, blood pressure, TG, high�]density lipoprotein cholesterol (HDL�]C), and fasting glucose were collected at baseline and 2 years later in 292 boys and 277 girls aged 8�]10 y. The results showed the percentage of children who remained overweight/obese defined on the basis of BMI, WC, WHtR and %BF was 89.7%, 93.5%, 84.5%, and 80.4%, respectively after 2 years. Obesity indices at baseline significantly correlated with TG, HDL�]C, and blood pressure at both baseline and 2 years later with a similar strength of correlations. BMI at baseline explained the greatest variance of later blood pressure. WC at baseline explained the greatest variance of later HDL�]C and glucose, while WHtR at baseline was the main predictor of later TG. Receiver�]operating characteristic (ROC) analysis explored the ability of the four indices to identify the later presence of CV risk. The overweight/obese children defined on the basis of BMI, WC, WHtR or %BF were more likely to develop CV risk 2 years later with relative risk (RR) scores of 3.670, 3.762, 2.767, and 2.804, respectively. The final purpose of the third study was to develop age�] and gender�]specific percentiles of WC and WHtR and cut�]off points of WC and WHtR for the prediction of CV risk in Chinese children. Smoothed percentile curves of WC and WHtR were produced in 2830 boys and 2699 girls aged 6�]12 y randomly selected from southern and northern China using the LMS method. The optimal age�] and gender�]specific thresholds of WC and WHtR for the prediction of cardiovascular risk factors clustering were derived in a sub�]sample (n=1845) by ROC analysis. Age�] and gender�]specific WC and WHtR percentiles were constructed. The WC thresholds were at the 90th and 84th percentiles for Chinese boys and girls, respectively, with sensitivity and specificity ranging from 67.2% to 83.3%. The WHtR thresholds were at the 91st and 94th percentiles for Chinese boys and girls, respectively, with sensitivity and specificity ranging from 78.6% to 88.9%. The cut�]offs of both WC and WHtR were age�] and gender�]dependent. In conclusion, the current thesis quantifies the ethnic differences in the BMI�]%BF relationship and body fat distribution between Asian children from different origins and confirms the necessity to consider ethnic differences in body composition when developing BMI and other obesity index criteria for obesity in Asian children. Moreover, ethnicity is also important in BIA prediction equations. In addition, WC and WHtR percentiles and thresholds for the prediction of CV risk in Chinese children differ from other populations. Although there was no advantage of WC or WHtR over BMI or %BF in the prediction of CV risk, obese children had a higher risk of developing the metabolic syndrome and abnormalities than normal�]weight children regardless of the obesity index used.
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Ibrahimović, Adisa. „Correlation between how glucagon levels reflect obesity in children with regards to weight, fat mass and fat free mass“. Thesis, Uppsala universitet, Institutionen för kvinnors och barns hälsa, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-349020.
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Background: Overweight and obesity constitutes a threat to public health all around the world, and more individual’s dies from obesity than from hunger. This condition is increasing worldwide and obesity also occurs in children. According to WHO, there are 42 million overweight children in the world. Obesity and overweight in childhood leads to insulin resistance, elevated blood lipids and cardiovascular effects. Obesity is caused by positive energy intake, poor exercise habits, environmental factors, food habits and stress etc. It is also known that hormones influence the incidence of obesity. It has been found that individuals with overweight and obesity has elevated glucagon levels in the bloodstream Purpose: This work aims to investigate whether there is a difference in glucagon concentration between the sexes at ages 10-18 years with obesity, and if there is an association between glucagon concentration and weight, FM and FFM. Materials and Methods: In this study, obesity is determined by BIA and the caliper in combination as three compartment model. Blood samples were taken by venipuncture and glucagon were analyzed in fasting plasma. Results: BIA and the caliper together had a significant correlation with body composition. Blood glucagon was found to be high in obese children. Conclusion: Glucagon concentration in obese children correlates with weight and FM. However, further investigation is needed regard to how glucagon interact with weight, FM and FFM
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Barros, Carla Valença. „Validação da impedância bioelétrica para determinação da composição corporal em mulheres no período pós parto“. Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=5027.
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O período pós-parto pode ser considerado a fase em que a mulher está exposta a retenção de massa corporal (MC) e desenvolvimento da obesidade. Na maioria das situações valorizam-se mais a perda de MC e pouco se conhece a respeito dos componentes que estão sendo mobilizados. Desta forma, há interesse de se validar técnicas acessíveis, como a impedância bioelétrica (BIA), que possam ser aplicadas no acompanhamento nutricional destas mulheres. O presente estudo teve como objetivo validar diferentes modelos de impedância bioelétrica (BIA) para a determinação da composição corporal em mulheres pós-parto tendo como ?padrão ouro? a técnica de absorciometria de dupla energia de raio X(DXA). A amostra foi composta por 46 mulheres no período pós-parto com idade acima de 18anos, inicialmente recrutadas e convidadas a participar da pesquisa, logo após o parto, para posteriormente serem avaliadas. A composição corporal (CC) foi mensurada através de três aparelhos distintos de BIA: RJL , BIO e Tanita e pela DXA. Os componentes101450BC 533corporais medidos foram: massa livre de gordura (MLG), massa gorda (MG) e percentual degordura corporal (%GC). Na análise estatística foram calculadas as médias e desvio-padrãodas variáveis contínuas. A concordância entre os componentes corporais determinados pelaDXA e cada BIA foi avaliada pelo método de Bland & Altman e pelo coeficiente decorrelação de concordância (CCC). Para comparação de médias das variáveis obtidas por BIAe DXA para cada faixa de índice de massa corporal (IMC), foi aplicada a ANOVA e oadotado o teste post-hoc de Tukey. O nível de significância adotado foi de 95% (p=0,05). Amédia ( desvio padrão) de idade foi de 25,5 4,6 anos, a MC de 73,6 12,2kg, o IMC de28,7 4,3kg/m, a MG de 29,87,4kg, a MLG de 43,25,7kg e o %GC de 41,84,3%,obtidos pelo DXA. Ao comparar-se os resultados dos diferentes equipamentos com o método padrão-ouro, verificou-se que houve diferença significativa entre a DXA e as BIA para todos componentes corporais, com exceção da MG fornecida pelo RJL (27,1Kg) e TAN (27,1Kg)em relação à DXA (29,8Kg). Os resultados mostraram haver uma boa reprodutibilidade emrelação aos aparelhos de BIA TAN (r=0,74; r=0,90) e RJL (r=0,78; r=0,89) para MLG e MG.Verificou-se que os equipamentos de BIA TAN e RJL forneceram estimativas semelhantes em relação à MLG, MG e %GC. Em relação aos valores da DXA o equipamento que mais se aproximou foi a TAN e o RJL quando avaliada a MG considerando todas as mulheres, mas quando estratificadas segundo o IMC, a análise foi mais acurada em mulheres obesas.Entretanto, a concordância não foi satisfatória entre os componentes corporais fornecidos pelas BIA em relação à DXA. As BIAs avaliadas no presente estudo subestimaram o %GC e superestimaram a MLG para esse grupo de mulheres no período pós-parto. Conclui-se que as BIA avaliadas não são recomendadas para avaliação da CC neste grupo de mulheres no período pós-parto.Postpartum women are at risk of body weight retention and consequently becoming obese. Usually, during postpartum period there is a greater concern in weight loss instead of measuring which body compartment is being mobilized. Thus, there is a growing interesting to validate field and affordable techniques, such as the bioelectrical impedance (BIA) to determine body composition in this segment of the population. The purpose of this study was to validate different BIA devices using dual-energy x-ray absorptiomety (DXA) as a goldstandard in postpartum women. Forty-six postpartum women aged 18 years and over were enrolled in the study. They were recruited soon after delivery from two health units (Hospital São José of Mesquita District and Policlínica Piquet Carneiro, located in Rio de Janeiro city).All measurements were performed at the Laboratório Interdisciplinar de Avaliação Nutricional da Universidade do Estado do Rio de Janeiro. Participants were instructed to follow a standardized protocol for body composition measurements. Anthropometric variables(body mass - BM, stature, waist and hip circumferences) were collected. Body composition was determined by DXA and also obtained using the following BIA devices :model RJL 101(RJL Systems, Inc. Clinton, USA), model BIOD 450 (Biodynamics Corporation, USA)and I model BC 533 (Tanita, USA). Descriptive statistical analysis was done for continuous variables. ANOVA was used to verify differences between mean values of fat free mass(FFM), fat mass (FM) and percentage body fat (%BF) within BIA devices and DXA. Concordance analysis between each body component obtained by DXA and all BIA devices were performed using Bland & Altman plots and the Concordance Correlation Coefficient(CCC). ANOVA was used to compare mean values within BIA and DXA, and Tukey post-hoc was adopted. SPSS and MedCalc software were used in the analysis. Mean values (standard deviation) of age, BM, body mass index, FM by DXA, FFM by DXA, %BF by DXA were 25.5 4.6 years, 73.6 12.2kg, 28.7 4.3kg/m, 29.87.4kg, 43.2 5.7kg, 41.8 4.3%,respectively. When comparing the results within different equipments (DXA, RJL, BIOD and TAN), it was verified that there was significant difference between DXA and BIA equipments for all body components, except for MG from RJL (27.1Kg) and TAN (27.1Kg) in relation toD XA (29.8Kg). The results showed good reproducibility in relation to BIA TAN (FFM, r=0.74; FM, r=0.90) and RJL (FFM, r=0.78; FM, r=0.89). It was verified that BIA TAN and RJL yielded similar estimates for FFM, FM and % BF. When all women were considered together no significant difference was observed for FM obtained by TAN, RJL and DXA. When considering BMI categories the estimates were better for obese women. However, the agreement was not satisfactory for body components supplied by BIA in relation to DXA. All BIA devices tended to underestimated % BF and overestimated FFM for this sample.
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Gonçalves, Ezequiel Moreira 1977. „Composição e proporções corporais de meninas com a forma classica de deficiencia da 21-hidroxilase“. [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309445.
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Orientador: Gil Guerra JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: A Hiperplasia Adrenal Congênita na forma clássica da deficiência da 21-hidroxilase (HAC-C-D21OH) caracteriza-se pela deficiência na síntese do cortisol e, em alguns casos, na aldosterona, e pelo excesso de andrógenos. O objetivo do estudo foi avaliar a composição e as proporções corporais de pacientes do sexo feminino com HAC-C-D21OH e comparar em relação ao controle, à forma clínica da doença e a um grupo controle de ambos os sexos. A casuística foi composta por 28 pacientes (grupo casos) do sexo feminino com HAC-C-D21OH divididas de acordo com o controle hormonal (bem e mal controladas) e com a forma da doença (virilizante simples e perdedores de sal). O grupo controle foi composto por 112 indivíduos saudáveis de ambos os sexos, divididos em dois grupos, de acordo com o gênero. Para verificar os efeitos da puberdade nas medidas avaliadas, os três grupos foram subdivididos em três faixas etárias: até 10 anos, de 11 a 14 anos e acima de 15 anos. Para a avaliação das proporções e composição corporais foram utilizadas medidas antropométricas e a impedância bioelétrica. Os dados das medidas antropométricas foram convertidos em escores de desvio padrão (z). Em relação à forma clínica da doença, as virilizantes simples apresentaram valores significativamente maiores de z do IMC, do perímetro da cintura e da área gorda do braço, e no percentual de massa gorda. Em relação ao controle laboratorial, as mal controladas apresentaram z do comprimento da perna significativamente menor. Os casos apresentaram valores significativamente maiores que os controles no z do IMC, área muscular e gorda do braço, perímetro braquial, da cintura e do quadril, do diâmetro biilíaco e no percentual de massa gorda, e menores no z do comprimento da perna e da mão e nos percentuais de água e massa magra. Pode-se notar que as alterações na composição corporal foram observadas em todas as faixas etárias, mas foram se intensificando com a idade, com o predomínio do aumento da massa gorda enquanto as alterações nas proporções corporais se tornaram mais evidentes após a puberdade, com comprometimento principal das extremidades (perna, mão e pé). As variáveis que melhor se ajustaram para diferenciar os grupos caso e controles foram o percentual de gordura, o comprimento da mão e o perímetro do quadril (94,7%). Esse grupo de pacientes apresentou diferenças nas proporções e principalmente na composição corporal, justificando uma avaliação antropométrica ampla e cuidadosa no monitoramento das pacientes com HAC-C-D21OH
Abstract: Congenital Adrenal Hyperplasia due to classical 21-hydroxylase deficiency (CAH-C-21OHD) is characterized by deficiency in the synthesis of cortisol, and, in some cases, also of aldosterone and by excess of androgens. The aim at of the study was to evaluate the body composition and body proportion of women with CAH-C-21OHD in relation to the control and the clinical form of the disease and to a group control of both sexes. The casuistic was composed by twenty-eight patient (cases group) female with CAH-C-21OHD were divided according to control (good or bad) and the clinical form of the disease (salt-wasting and simple-virilizing). The control group was composed by 112 healthy individuals of both sexes, divided in 2 groups, in agreement with the gender. To verify the effects of the puberty in the appraised measures, the 3 groups were subdivided in 3 age groups: up to 10 years, from 11 to 14 years and above 15 years. To evaluate body proportions and composition, anthropometric measurements and electric impedance were analyzed. The data of anthropometric measurements were converted in standard deviation scores (z). In relation to clinical form of the disease, the simple-virilizing presented values significantly larger of z of BMI, of the perimeter of the waist and of the fat area of the arm, and in the percentage of fat mass. In relation to disease control, the patients with bad control showed significantly lower leg length. The cases showed significantly higher values in relation to controls in z of BMI, arm muscle and fat area, brachial perimeter, of the waist and of the hip, of the biiliac diameter and in the fat percentage and smaller in z of the length of the leg and of the hand and in the percentages of water and lean mass. Alterations in the body composition were observed in all of the age groups, but they were if intensifying with the age, with the prevalence of the increase of the fat mass while the alterations in the body proportions if they turned more evident after the puberty, with main compromising of the extremities (leg, hand and foot). The more adjusted variables to explain the differences between cases and controls were percentage of fat mass, hand length and hip perimeter, comprising 94.7% of the differences between the groups. This group of patients showed differences in body proportions, but mainly in body composition, justifying a broad and careful anthropometric evaluation in the monitoring of CAH-C-21OHD patients
Mestrado
Saude da Criança e do Adolescente
Mestre em Saude da Criança e do Adolescente
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Ayub, Pollyanna. „Comparação da bioimpedância frente ao padrão ouro para composição corporal em idosas“. Universidade Católica de Brasília, 2018. https://bdtd.ucb.br:8443/jspui/handle/tede/2461.
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Objective: to compare distinct bioimpedances (BIAs) in front of the gold standard for body composition in elderly women, verifying the existence of a correlation between the methods and the necessity or not of using a previous protocol of hydration. Methods: a cross-sectional, descriptive and comparative study with 83 elderly women aged 60 years or older attending the Center for the Cohabitation of the Elderly at the Catholic University of Brasília. In order to determine the body composition, we used x - ray Absorptiometry (DXA), InBody 120 and Biodynamics 310e, with and without hydration protocol. Results: Bioimpedance only showed no difference with and without protocol (p = 0.70). Among the age groups there was no difference in fat percentage (p = 0.44) and fat free lean mass (p = 0.22). In the total sample, Bioimpedances underestimate the percentage of body fat and underestimate lean fat free mass compared to DXA. According to nutritional status by the InBody 120, the percentage of fat in the elderly women with low weight, eutrophic and obese were equal to the DXA and fat-free lean mass in obese women. Conclusion: BIA is an instrument capable of measuring body composition in elderly women in front of DXA, but it is necessary to verify the accuracy of the equipment, since both the measurement of the body composition and the performance or not of the hydration protocol will exist differences in the results, independent of the hydration protocol or not.
Objetivo: Determinar o nível de concordância entre dois equipamentos de bioimpedâncias elétricas frente ao padrão-ouro Absorciometria por dupla emissão de Raios – x (DXA), na avaliação da composição corporal em idosas; conferir, pelo método DXA, se existe alteração na composição corporal por faixa etária – 60 a 64, 65 a 69 e 70 anos ou mais e verificar se existe diferença, utilizando-se o método de bioimpedância, na Porcentagem de Gordura Corporal (%GC), Massa Magra Livre de Gordura (MMLG) e Taxa de Metabolismo Basal (TBM), quando o protocolo de hidratação é realizado ou não. Métodos: estudo transversal, descritivo e comparativo com 83 idosas de 60 anos ou mais que frequentam o Centro de Convivência do Idoso da Universidade Católica de Brasília. Para determinar a avaliação da composição corporal utilizou-se os equipamentos (DXA), InBody 120 e Biodynamics 310e, com e sem protocolo de hidratação. Resultados: apenas na BIA 120 não houve diferença com e sem protocolo (p=0,70). Entre as faixas etárias não houve diferença na porcentagem de gordura (p=0,44) e massa magra livre de gordura (p= 0,22). Na amostra total, as Bioimpedâncias subestimam a porcentagem de gordura corporal e subestimam massa magra livre de gordura em comparação à DXA. De acordo com estado nutricional pelo IMC a InBody 120, o percentual de gordura nas idosas com baixo peso, eutróficas e obesas foram iguais à DXA e a massa magra livre de gordura em obesas. Conclusão: a BIA é um equipamento apto a mensurar a composição corporal em idosas em frente à DXA, porém é necessário verificar a precisão do equipamento, pois tanto na mensuração da composição corporal quanto na realização ou não do protocolo de hidratação existirão diferenças nos resultados, independente do protocolo de hidratação ou não.
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Soussan, Dimitri. „Contributions aux interfaces d'entrées / sorties rapides en technologies Silicium-Sur-Isolant partiellement et totalement désertées“. Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00935123.
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Des spécificités de la technologie SOI partiellement désertée (PD-SOI), comme son gain en vitesse, et l'isolation diélectrique des transistors, sont intéressantes pour la conception d'interfaces entrées/sorties. Toutefois, l'emploi de cette technologie conduit à des phénomènes indésirables tels que l'effet d'histoire, une consommation statique accrue et l'effet d'auto-échauffement. Dans ce travail, une analyse de ces effets a été menée. L'influence de l'auto-échauffement s'est révélée négligeable. Un schéma électrique employant un mécanisme de polarisation active a été proposé afin de supprimer l'effet d'histoire et de contrôler la consommation statique tout en conservant un gain en vitesse. Le circuit de test, en 65nm PDSOI de STMicroelectronics, montre que la solution proposée permet d'améliorer la gigue du temps de propagation lors d'une transmission. La deuxième partie de ce travail s'intéresse à la technologie SOI totalement désertée (FDSOI). Cette dernière apporte un meilleur contrôle électrostatique des transistors et un degré de liberté supplémentaire en conception par le contrôle de leurs tensions de seuil via la face arrière. Dans un premier temps, cette caractéristique a été validée pour les entrées/sorties sur un circuit fabriqué en 28nm FDSOI de STMicroelectronics. Elle a été ensuite exploitée pour la calibration de l'impédance de sortie d'une interface LPDDR2 et la compensation des fluctuations environnementales. La solution proposée dans ce travail tire profit de la modulation par face arrière pour réaliser la calibration durant la transmission, contrairement à l'état de l'art, ce qui a pour effet d'augmenter la bande passante.
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Sharpe, Jenny-Kay. „Body composition and energy expenditure in men with schizophrenia“. Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16961/1/Jenny-Kay_Sharpe_Thesis.pdf.
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There is an increase in the prevalence of obesity among people with schizophrenia thought to be due in part to the weight enhancing side-effects of medications commonly used to treat the symptoms of schizophrenia. Despite the deleterious health effects associated with obesity and its impact on quality of life and medication compliance, little is known about body composition and energy expenditure in this clinical group. The primary purpose of this thesis was to enhance understanding of body composition and energy expenditure, particularly resting energy expenditure in men with schizophrenia who take atypical antipsychotic medications. Unique to this investigation is the evaluation of clinical tools used to predict body composition and energy expenditure against reference methodologies in men with schizophrenia. Further, given the known links between obesity and physical activity, an additional but less comprehensive component of the thesis was a consideration of total and activity energy expenditure in addition to the interaction between psychiatric symptoms, side-effects of antipsychotic medications and physical activity also occurred as part of this thesis. Collectively, the goals of this thesis were addressed through a series of studies – the first two studies were related to the measurement and characteristics of body composition in men with schizophrenia, while the third and fourth studies were related to the measurement and characteristics of resting energy expenditure in men with schizophrenia. The fifth and sixth studies the utilised doubly labelled water technique to quantify activity and total energy expenditure in a small group of men with schizophrenia and explored the use of accelerometry in this cohort. The final study briefly considered the impact of psychiatric symptoms and self-reported medication side-effects on objectively measured physical activity. In the first study, thirty-one male adults previously diagnosed with schizophrenia and sixteen healthy male controls were recruited. Estimates of body composition derived from an anthropometry-based equation and from bioelectric impedance analysis (BIA) using deuterium dilution as the reference methodology to determine total body water were compared. The study also determined the validity of equations commonly used to predict body composition from BIA in the men with schizophrenia. A further aim was to determine the superiority of either BIA or body mass index (BMI) as an indicator of obesity in this cohort. The inclusion of the control group, closely matched for age, body size and body composition demonstrated that there was no difference in the ability of body composition prediction methods to distinguish between fat and fat-free mass (FFM) in controls and men with schizophrenia when both groups had similar body composition. However this study indicated that an anthropometry-based equation previously used in people with schizophrenia was a poor predictor of body composition in this cohort, as evidenced by wide limits of agreement (25%) and systematic variation of the bias. In comparison, the best predictor of percentage body fat (%BF) in this group was gained when impedance values were used to predict percentage body fat via the equation published by Lukaski et al (1986). Although percentage body fat was underpredicted using the Lukaski et al. (1986) equation, the mean magnitude was relatively small (1.3%), with the limits of agreement approximately 13%. Linear regression analysis revealed that %BF predicted using the Lukaski et al. (1986) equation explained 25% more of the variance in percentage body fat than BMI. Further, this study also indicated that BIA was more sensitive than BMI in distinguishing between overweight and obesity in this cohort of men with schizophrenia. Because of the almost exclusive use of BMI as an indicator of obesity in people with schizophrenia, the level of excess body fat may be in excess of that previously indicated. The second study extended the examination of body composition in men with schizophrenia. In this study, the thirty-one participants with schizophrenia (age, 34.2 ± 5.7 years; BMI, 30.2 ± 5.7 kg/m2) were individually matched with sedentary controls by age, weight and BMI. Deuterium dilution was used to distinguish between FFM and fat mass. The previous study had indicated that while BIA was a suitable group measure for obesity, on an individual level the technique lacked the precision required for investigating body composition in men with schizophrenia. Waist circumference was used as an indicator of body fat distribution. The findings of this study indicated that in comparison with healthy sedentary controls of similar body size and age, men with schizophrenia had higher levels of body fat which was more centrally distributed. Percentage body fat was on average 4% higher and waist circumference, on average 5 cm greater in men with schizophrenia than the sedentary controls of the same age and BMI. Further, this study indicates that the use of BMI to predict body fat in men with schizophrenia will result in greater bias than when it is used to predict body fat in other sedentary men. Commonly used regression equations to predict energy requirements at rest are based on the relationships between weight and resting energy expenditure (REE) and in such equations, weight acts as a surrogate measure of FFM. The objectives of study three were to measure REE in a small group of men with schizophrenia who were taking the antipsychotic medication clozapine and to determine whether REE can be predicted with sufficient accuracy to substitute for the measurement of REE in the clinical and/or research settings. Body composition was determined using deuterium dilution and REE was measured using a Deltatrac Metabolic Cart via a ventilated hood. The male participants, (aged 28.0 ± 6.7 yrs, BMI 29.8 ± 6.8 kg/m2) were weight stable at the time of the study and had been taking clozapine for 20.5 ± 12.8 months, with doses of 450 ± 140 mg/day. Of the six prediction equations evaluated, the equation of Mifflin et al. (1990) with no systematic bias, the lowest bias and the lowest limits of agreement proved to be the most suitable equation to predict REE in this cohort. The overestimation of REE can be corrected for by deducting 160 kcal/day from the predicted REE value when using the Mifflin et al. (1990) equations. However, the magnitude of the error associated with the prediction of REE for an individual is 370 kcal/day. The findings of this study indicate that REE cannot be predicted with sufficient individual accuracy in men with schizophrenia, therefore it was necessary to measure rather than predict REE in subsequent studies. In the fourth study, indirect calorimetry (Deltatrac Metabolic Cart via ventilated hood) and deuterium dilution were used to accurately determine REE, respiratory quotient (RQ) and FFM in 31 men with schizophrenia and healthy sedentary controls individually matched for age and BMI. Data from this study indicated that gross REE was lower in men with schizophrenia than in healthy sedentary controls of a similar age and body size. However, there was no difference between the groups in REE when REE was adjusted for FFM using the mathematically correct method (analysis of covariance with FFM as the covariate). There was however a statistically and clinically significant difference in resting, fasted RQ between men with schizophrenia and controls, suggesting that RQ rather than REE may be an important correlate worthy of further investigation in men with schizophrenia who take antipsychotic medications. Studies five and six involved the application of the doubly labelled water (DLW) technique to accurately determine total energy expenditure (TEE) and activity energy expenditure (AEE) in a small group of men with schizophrenia who had been taking the atypical antipsychotic medication clozapine. The participants were those who took part in study three. The purpose of these studies was to assess the validity of a commercially available tri-axial accelerometer (RT3) for predicting free-living AEE and to investigate TEE and AEE in men with schizophrenia. There was poor agreement between AEE measured using DLW and AEE predicted using the RT3. However, using the RT3 to measure inactivity explained over two-thirds of the variance in AEE. This study found that the relationship between current AEE per kilogram of body weight and change from baseline weight in men taking clozapine was strong although not significant. The sedentary nature of the group of participants in this study was reflected in physical activity levels, (PAL, 1.39 ± 0.27), AEE (435 ±352 kcal/day) and TEE (2511 ± 606 kcal/day) that fell well short of values recommended by WHO (2000) for optimal health and to prevent weight gain. Given the increasing recognition of the importance of sedentary behaviour to weight gain in the general community, further examination of the unique contributing factors such as medication side effects and symptoms of mental illness to activity levels in this clinical group is warranted. The final study used accelerometry (RT3) to objectively measure activity in a group of 31 men with schizophrenia who had been taking atypical antipsychotic medications for more than four months. The purpose of this study was to explore the relationships between psychiatric symptomatology, side-effects of medication and physical activity. Accelerometry output was analysed to provide a measure of inactivity and moderate intensity activity (MIA). The well-validated and reliable standardised clinical interview, the Positive and Negative Syndrome Scale (PANSS) was used as a measure of psychiatric symptoms. Perceived side-effects of medication were assessed using the Liverpool University Neuroleptic Rating Side-Effects Scale (LUNSER). Surprisingly, there was no relationship reported between any measures of negative symptoms and physical inactivity. However, self-reported measures of medication side-effects relating to fatigue, sleepiness during the day and extrapyramidal symptoms explained 40% of the variance in inactivity. This study found significant relationships between some negative symptoms and moderate intensity activity. Despite the expectation that as symptoms of mental illness reduce, inactivity may diminish and moderate intensity activity will increase, it may not be surprising that in practice this is an overly simplistic view. It may be that measures of social functioning and possibly therefore cognition may be better predictors of physical activity than psychiatric symptomatology per se.