Dissertations / Theses on the topic 'Whole body vibration'

Obiettivo di questa tesi è la determinazione e quantificazione degli effetti della whole-body vibration al corpo umano, in termini di consumo energetico, tramite un approccio globale e integrato. L’obiettivo è ottenuto considerando il corpo umano come una struttura organica complessa. Allo scopo di comprendere come questo risponda alle vibrazioni verticali, il consumo energetico del corpo umano è stato misurato per mezzo della variazione della temperatura superficiale con tecniche di misurazione a termografia infrarossa. Lo spostamento dei muscoli invece con il sistema di analisi di movimento Vicon MX. Infine, per quanto riguarda il consumo di ossigeno con il sistema telemetrico Cosmed K4. Il primo passo è stato l’istituzione di un protocollo appropriato che soddisfi l’obiettivo di questo studio. Infatti, la mancanza di coerenza nei protocollo di whole-body vibration che si trovano allo stato dell’arte, ha reso essenziale l’istituzione di un apposito protocollo, ed a questo scopo è stata definita la struttura dell’esperimento. Di conseguenza, è stata avviata una serie di prove per esaminare la risposta del corpo umano alle vibrazioni verticali, cambiando la durata e la frequenza della vibrazione, nonché la durata del periodo di riposo. In totale, quattro persone in piedi sono state sottoposte a vibrazioni verticali, in una pedana vibrante, a frequenze da 20 a 50 Hz. Dopo l’instaurazione del protocollo finale, sono stati avviate una serie di prove di laboratorio. In particolare, sono state scelte tre frequenze per le vibrazioni: 20, 30 e 45 Hz. I risultati ottenuti più interessanti di questo studio, riguardano il consumo di ossigeno, la temperatura superficiale e i coefficienti di trasmissibilità dell’accelerazione.
The objective of this thesis is to determine and quantify the effects of whole-body vibration to the human body in terms of energy expenditure, by means of a global and integrated approach. This objective is attained by considering the human body as a complex organic structure. In order to understand how it responds to vertical vibrations, the energy expenditure of the human body was measured by means of the variation in superficial temperature with the aid of infrared thermography, the displacement of the muscles with the aid of the Vicon MX motion analysis system and the oxygen uptake with the aid of the Cosmed K4 telemetric system. The establishment of an appropriate protocol which satisfies the aim of this study was the first goal. The lack of consistency in whole-body vibration protocols in the current published studies makes the establishment of an appropriate protocol essential, and in this sense, an experiment setup was implemented. Therefore, a series of experiments was conducted to examine the response of the human body to vertical vibrations, changing the duration and the frequency of vertical vibration, and the duration of rest period. A number of four persons were subjected to vertical vibrations on a vibrating table in a standing position at a frequency ranging from 20 to 50 Hz. After the establishment of the final protocol, a series of laboratory experiments took place. Three different vibration frequencies were chosen: 20, 30 and 45 Hz corresponding to three different tests. The most interesting findings regard the oxygen consumption, the superficial temperature evolution, and the transmissibility coefficients for the acceleration.

Whole-body vibration (WBV) has been identified as a stressor to supine patients with head and spinal injuries during medical transportation. Limited information is available on the dynamic effects of the long spinal board and stretcher in vibrating environments. This is the first study to investigate the transmission of vibration through the long spinal board, military stretcher, and supine human in relation to a control case with full-rigid support. A sample of eight healthy male participants was used in this study. Each was placed on a vibration platform using spinal immobilization. Random vibration was applied in the fore-aft, lateral, and vertical directions, and the transmission of vibration was computed for the head, sternum, and pelvis. In addition, a novel approach to assess relative motion between segments, called relative transmissibility, was introduced. Compared to full-rigid support, the long spinal board strapped to a standard military litter system showed a 50% increase in transmission of anterior-posterior vibration to the head and a 100% increase to the sternum at its resonance frequency of 5 Hz (p < 0.05, Wilcoxon) for vertical vibration. Use of the cervical collar during immobilization increased the head nodding and the relative head-sternum flexion-extension as a result of the input fore-aft (axial) whole-body vibration. Yet, head nodding was reduced from vertical (anterior-posterior) input vibration. Relative transmissibility has revealed that at 5 Hz, the acceleration difference between the head and sternum was 1.5 times the vertical (anterior-posterior) input acceleration using the spinal board upon the military litter. During air, ground, and hand transportation, WBV may occur around 5 Hz. Patients with head and spinal cord injuries may benefit from vibration-suppression designs that minimize (1) the overall transmission of vibration in each axis and (2) the relative accelerations between segments for the most common vibration frequencies that occur during transportation. Furthermore, vibration applied in each axis independently showed transmissibility results comparable to that of simultaneous stimuli in three axes. Although the effects of vibration are quantified in this study, transient shock type vibration should be investigated and future research should be done to fully understand the clinical significance and application of these results.

Thesis (M.S.)--West Virginia University, 2000.
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Vibrations are often experienced in the workplace and may influence performance and executive function. Research has shown that vibrations may have an affect effect on drowsiness and tests related to inhibitory control. Previous work investigating whole body vibrations (WBV) and their effect was evaluated to inform the decisions for this study. WBV effects on cognitive abilities were examined and the different tests used in these studies were identified and compared. Electroencephalogram (EEG) and event related potentials (ERP) were selected to be used to measure inhibitory and cognitive processes. The N2 ERP, which reflects inhibitory control processes, was examined as well as the dominant frequency of the Fourier fast transform (FFT). A total of 94 participants between the ages of 18-55 (Mage = 20.49 SDage = 1.68) completed this study (51 female, 38 male and 5 with no gender listed). A go/no-go task was used to elicit the N2 ERP after WBV and a simultaneous EEG recording while the participants experienced WBV was used to gather the needed data. Stimulus frequencies used for the N2 ERP included 15 Hz, 20 Hz, and 40 Hz. During the simultaneous recording stimulus frequency varied every 30 seconds by 10 Hz from 20 Hz to 110 Hz. Data were analyzed using both a linear mixed effects model for normally distributed data and a generalized linear mixed effects model for data taken as percentages. It was hypothesized that there would be an effect on performance as measured in the raw go/no-go results, that this change in performance showing improved accuracy would be linked to inhibitory control, and be seen as a decrease in the magnitude of the N2 ERP. It was also hypothesized that the exploratory FFT portion of the study would produce a shift from a higher to a lower frequency in the dominant waveform . The results show that there were no main effects in either the behavioral performance or in the N2 ERP of the participants but that there was a significant interaction at 40 Hz with improved simple go trial activity and decreased no-go inhibition. The results also show that there was a statistically significant shift in neural oscillation activity but that this shift was not real-world relevant within the context of this study.

Whole body vibration (WBV) delivers a stimulus to the body via an oscillating platform and remains a relatively new area of research. Several applications of WBV stimuli have been developed as strength training and rehabilitation modalities, but inconsistent results have been published. There is little knowledge underpinning the mechanisms to explain the elicited neuromuscular responses to WBV and a wide range of WBV parameters across the literature. As a result, safe and effective protocols are yet to be established or validated. The aim of this current research was to investigate: the electromyography (EMG) and explosive performance responses to varying WBV frequencies; the effect of WBV data analysis techniques; and the influence of external factors on WBV stimulus and neuromuscular responses. Three main studies were completed: 1. An individualised response of both EMG and jump performance appears to exist dependent on vertical WBV frequency, in trained participants. This is in spite of no overall frequency dependent effect of EMG or performance responses across participants as a group. The influence of the role of expectancy effect appears minimal following this particular WBV protocol. 2. There was a significant effect of filter technique on EMG data recorded during vertical WBV. A tailored, WBV specific notch filter technique may offer an effective balance; excluding WBV noise artifacts without removing significant portions of valuable muscle signal EMG data. 3. The influence of external load on WBV acceleration output also appears minimal. Platform acceleration output was dependent on WBV frequency, as expected. Lower accelerations were recorded in superior body segments, suggesting a dampening mechanism, which was also proportionally dependent on frequency. EMG activity of upper and lower leg segments may differ in response to frequency, likely due to transmission distances involved. This may partially account for a potential dampening mechanism. In addition, a protocol to quantify WBV stimuli delivered by this particular WBV type illustrated significant differences in theoretical and actual parameters. This may explain not only the lack of overall explosive performance effect reported earlier; but also the inconsistent WBV literature. Future research should quantify WBV stimulus before investigating possible neuromuscular responses to individualised protocols, which may be assessed via EMG activity.

Low back disorders and their prevention is of great importance for companies and their employees. Whole-body vibration is a risk factor for low back disorders, but the neuromuscular, biomechanical, and/or physiological mechanisms responsible for this increased risk are unclear. These studies investigated changes in the biomechanics and control of the trunk in order to further the understanding of the mechanisms responsible for this increased risk. The purpose of the first study was to measure the acute effect of seated whole-body vibration on the postural control of the trunk during unstable seated balance. The findings show that whole-body vibration impaired the postural control of the trunk as evidenced by increased kinematic variance and non-linear stability control measures during unstable sitting. These findings imply an impairment in spinal stability control. The purpose of the second study was to measure the effect of seated whole-body vibration on the parameters of spinal stability control: passive stiffness, active stiffness, and neuromuscular reflexes. The findings show that whole-body vibration altered trunk stiffness (passive stiffness and equivalent reflex stiffness) as well as reflex dynamics. There was no evidence of compensation by active muscle co-contraction recruitment for the decreased trunk stiffness and reflex gain. The purpose of the third study was to measure the changes in the natural frequency characteristics of the trunk (which can be related to trunk stiffness and damping) during exposure to seated whole-body vibration. The findings show that whole-body vibration caused a decrease in natural frequency suggesting a decrease in the trunk stiffness, and also an increase in the peak amplitude of the frequency response functions suggesting a decrease in overall trunk damping. The rate of change of the natural frequency characteristics suggest that the majority of effects happen within the first 10 minutes of vibration exposure. These findings reveal changes in the biomechanical properties of the trunk with exposure to seated whole body vibration, and a mechanism by which vibration may increase the risk of low back injury.
Ph. D.

The aim of the study was to determine and document evidence of the comparative effect of a 12- week whole body vibration training programme, exercise training programme and sedentary control group on the anthropometric profile, aerobic capacity, lung volumes and hence, the pulmonary capacity in people with asthma. The study used a descriptive, exploratory, quasi-experimental research approach employing randomised pairing to classify participants into either the whole body vibration therapy or exercise training group. Accidental and snowball sampling was used to identify and obtain a base of volunteers. A three-group pre-test/post-test design was employed to gain insight into statistical differences that might be apparent between the whole body vibration therapy group, the exercise group and the control group, and which could potentially be attributed to participation in the whole body vibration exercise programme. Randomised pairing for participant selection was selected because of the potential effects varying pulmonary variables might have had on the reliability of the study. A Physical Activity Selection Criteria Questionnaire was completed by participants to ascertain baseline physical activity readiness and as a means of determining selection criteria for their allocation to the whole body vibration training group, the experimental exercise group or the true control group. The pre-test/post-test assessment made use of a combination evaluation that incorporated an anthropometric profile assessment of height, weight, biceps, triceps, subscapular and suprailliac skinfolds, waist and hip circumference and posture, an aerobic capacity evaluation that incorporated aspects of both the YMCA and Astrand and Rhyming Physical Work Capacity (PWC) evaluation on a cycle ergometer and, lastly, a pulmonary variable assessment that made use of both the Datospir Peak-10 peak flow meter and the Spirovit SP-100AT spirometry unit integrated into the Cardiovit AT-6 model for all spirometry measurements. Participants were required to complete either the whole-body vibration or the exercise training programme a minimum of twice a week and a maximum of four times over the same period. The duration of the intervention programmes was approximately 30 minutes and consisted of three sections including a warm-up comprising flexibility exercises, whole body strength training exercises, and a cool-down which, in turn, consisted of massage exercises or replicated flexibility exercises. The main difference between the whole body vibration and exercise training group thus lay in the exclusion of the use of vibration for those participants assigned to the exercise training programme. Analysis of data was performed using descriptive and inferential statistics with the help of a qualified statistician. The identified variables were tested at a 95 percent level of probability (p<0.05) as recommended by Thomas and Nelson (1996:117). Descriptive data, in the form of a statistical mean, standard deviation, minimum, median and maximum values, obtained during this study were reported in the form of a t-score for selected anthropometric and pulmonary variables. The 12-week intervention programme, on analysis of the results, produced statistically insignificant improvements in the variables of anthropometric profile, aerobic capacity and lung volumes identified as determinants of, and factors influencing, the cardiorespiratory fitness level of participants with asthma and hence, the subsequent severity of this chronic condition. However, slight mean increases for the whole body vibration training group were evident for certain variables identified in this study. Based on the results, the inference could be made that whole body vibration therapy and exercise were both effective modes of training to improve the cardiorespiratory fitness level of people with asthma, but the results of the study did not show sufficient practical or statistical significance to verify the assumption that whole body vibration training was a method superior to conventional exercise training. Hence, the significance of whole body vibration training on the pulmonary variables of people with asthma could not be determined. The researcher recommends that future studies be undertaken to verify whether whole body vibration training incorporating larger participant groups could produce significant improvements in pulmonary variables in people with asthma.

Exposure to acute bouts of whole body vibration (WBV), which can be employed as a novel form of exercise, has been reported to increase local skeletal muscle blood flow. However, the mechanism for this effect remains unclear. Therefore, this research aimed to explore the mechanism that would explain the effect of vibration on the peripheral cardiovascular function. Initially, the aim was to investigate the potential mechanism of the effect of WBV on the systemic blood flow, since there are currently no studies reporting any systemic effects of WBV on blood flow. The results did not demonstrate any systemic effects on blood flow (i.e. forearm blood flow) in response to acute unloaded and loaded squats with WBV. It was concluded that it was difficult to identify the effects of vibration on systemic cardiovascular function because, most likely due to the higher exercise intensity, skeletal muscle activation resulted in a decrement in blood flow from a distal site (i.e. forearm) to the main site (i.e. lower limb). Through the development of experimental methods involving applying vibration passively to the lower limbs, which avoids any influence of direct skeletal muscle activation and focuses solely on the mechanism inducing effects, it was demonstrated that ankle systolic blood pressure and ankle brachial pressure index substantially decreased in the post-vibration period. It was concluded that vibration has a direct effect on the peripheral cardiovascular function via increased vasodilatation; however, the mechanism underlying this effect remained unresolved. The effects of different durations of passive vibration on the peripheral circulation were also investigated and the results demonstrated that a longer duration of passive vibration (i.e. 8 minutes) resulted in a significantly higher lower leg blood flow during the recovery period than a shorter duration (i.e. 1, 2 and 4 minutes) of passive vibration. These data provide evidence for a greater effect of WBV occurring with a longer duration on the peripheral cardiovascular function, caused by the vasodilatation response throughout the recovery period. However, there might be a minimum effect of skeletal muscle activation occurring with a longer duration of passive vibration that leads to a direct response to localised heating. Furthermore, the thesis attempted to distinguish the effects of passive vibration on skeletal muscle activation from those on the peripheral vascular system. An experiment was designed in which passive vibration was applied with and without circulatory occlusion, to examine whether there was any underlying skeletal muscle activation. It was found that vibration with intact circulation produces more heat than the control, no vibration and occlusion, and occlusion plus vibration conditions. These effects were reflected by the higher skin temperature observed during exposure to vibration, and continuing into recovery. These data provide evidence that passive vibration does not appear to induce an increase in muscle activity. The data also suggest that the mechanism of the rise in skin temperature in response to passive vibration exposure is due to a vasodilatation that occurred in the lower limb via inducing an increase in shear stress at the blood vessels wall and led to an increase in circulating blood flow during exposure that continues into recovery. Overall, the results obtained demonstrate that vasodilatation occurs during and after vibration exposure and appears to be a process that is independent of skeletal muscle activation. It is postulated that the stimulus is a direct effect on the blood vessels via inducing an increase in shear stress that results in an increased vasodilatation, thereby increasing blood flow. Hence, these observations demonstrate that vibration stimulus has a direct effect on the muscle vascular bed as a primary effect and that there is no carry over effect into the systemic circulation. Thus, the results of this thesis indicate that vibration induced enhancement in the peripheral circulation could be using as a training stimulus and also could have a beneficial effect in assisting recovery routines from exertion.

Muscle pull from regular physical activity is crucial for optimal development of the skeleton during growth and maintenance of bone mineral density (BMD) throughout life. Mitochondrial Respiratory Chain Disorders (MRCD) and Cystic Fibrosis (CF) are two chronic diseases that exhibit reduced lean tissue mass and impaired exercise capacity, which negatively impacts bone health in these populations. Whole body vibration training (WBVT) is an emerging therapeutic modality that has been successful in improving BMD and muscle mass and function in heath and disease. Aim: To evaluate whether 6 months of home-based WBVT improves BMD, muscle function, exercise capacity and quality of life (QoL) in people with MRCD or CF. Methods: Participants were enrolled for 15-18 months: 3-6 months observation; 6 months home-based WBVT (3 x 3mins daily at 20Hz on a Galileo® Home vibration platform); 6 months follow-up. Participants attended four study visits and completed: dual energy x-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) to assess BMD; muscle function testing on the Leonardo Jumping Platform (LJP); 6-minute walk test (6MWT) and/or formal exercise testing to assess exercise capacity; and disease specific QoL questionnaires. Linear mixed models analysis was used to assess changes between visits. Results: The MRCD cohort had 23 participants (13 male) mean (SD) age 31.0 (19.8) years and the CF cohort, 16 participants (8 male) mean (SD) age 12.8 (3.5) years. Statistically significant improvements in BMD of the legs were seen in the MRCD and CF cohorts for both DXA and pQCT. Muscle force during hopping and co-ordination during the chair rise test on the LJP improved significantly post WBVT in the CF. Exercise capacity did not change in the MRCD or CF cohorts after WBVT. QoL showed improvements in both cohorts. Conclusions: WBVT was well tolerated. WBVT improved BMD, aspects of muscle function, and QoL in people with MRCD or CF and may be a useful adjunct to physiotherapy exercise programs.

Whole body vibration training (WBVT) has gained a lot of interest for its proposed benefits across a range of populations both active and injured. The purpose of the present thesis was to test the efficacy of WBVT in terms of injury rehabilitation and performance enhancement amongst professional and amateur athletes. The five papers submitted for the degree of PhD by publication are grouped into two key themes relevant to the development of knowledge and evidence to advance a better understanding of the chronic and acute effects of WBVT. The themes encompass the efficacy of WBVT (Chronic) as a rehabilitation tool and as an addition to a warm-up routine (acute). The explanatory narrative provides a brief background to WBVT, a summary of each paper and what the paper has contributed to the field both in terms of knowledge and methodological development. The papers presented provide evidence that chronic WBVT is an effective method of improving balance and stability in athletes suffering functional ankle instability (FAI) (Paper 1). Even when compared to traditional methods of rehabilitation for FAI, the addition of WBVT enhances the benefits of traditional rehabilitation protocols (Paper 2). The use of acute WBVT enhances reactive strength, again showing a significant benefit as an addition to a more traditional warm-up (FIFA 11+) amongst amateur soccer players (Paper 3). When training status was considered (amateur vs. professional), high frequency acute WBVT stimulus significantly improved landing stability (DPSI) amongst professional players only (Paper 4). These differences between groups were also identified when examining knee extensor potentiation and force output with significant improvements amongst professional but not amateur soccer players. Professional players also reported significantly greater beliefs in the effectiveness of WBVT (Paper 5). In conclusion the body of work presented discusses the practical and methodological implications of the new knowledge presented and identifies a series of future lines of research.

Currently, whole-body vibration is being used to promote enhanced performance. Many coaches and athletes believe that it can acutely enhance explosive performance and power output. However, the scientific literature is unclear as to whether this enhancement occurs. The purpose of this study was to examine the acute effects of whole-body vibration on static jump performance, including jump height, peak force, rate of force development, and peak power. Fourteen recreationally active individuals (5 females, 9 males) participated in three separate randomized treatment sessions. Treatment 1 consisted of no vibration while treatment 2 and treatment 3 incorporated whole-body vibration. The whole-body vibration protocol consisted of three 30-s bouts of vibration performed at 30 Hz and low amplitude ( 3 mm) with a 30-s rest between bouts. Treatment 1 was identical in duration to both treatments 2 and 3, but did not contain any vibration. Five minutes after each treatment, the participants performed the static jump protocols. Two (data averaged) non-weighted static jumps and two 20 kg weighted jumps were performed. Treatments 1 vs. 2, 1 vs. 3, and 2 vs. 3 were calculated for each variable at both 0 kg and 20 kg. Jump height, peak force, rate of force development, and peak power were analysed using a one-way analysis of variance with repeated measures. The intra-class correlations comparing the two trials of each jump for each of the three treatments were ≥0.92. Compared with the no-vibration condition, jump height showed a non-significant increase as a result of whole-body vibration for both unweighted and weighted jumps; peak force, rate of force development, and peak power were not statistically different. The results indicate that whole-body vibration has no effect on jump height, peak force, rate of force development or peak power during static jumping.

Introduction: Very few studies have looked at the effect of vibration on flexibility, and no studies exist that have looked at stretching concurrently with whole body vibration (WBV) training. Therefore, the purpose of this study was to determine if whole-body-vibration training (WBV) done concurrently with static stretch (SV) is more effective than static stretching alone (SS), and to see if WBV training independently (SQ) improves hamstring flexibility without stretching. A secondary purpose of this study is to determine if retention of flexibility gains are maintained. Methods: Forty-four subjects (31 men, 13 women) completed this study (age 22.5 ± 1.8 years; body mass 75.54 ± 13.18 kg; height 176.7 ± 8.06 kg). All subjects were randomly assigned to 1 of 5 groups: SV group (8 males, 3 females), SQ group (8 m, 4 f), SS group (8 m, 3 f), and the C group (7 m, 3 f). All subjects were measured bilaterally for hamstring flexibility using the lying passive knee extension test (LPKE) prior to group assignment. Subjects from each treatment group reported to lab 5 times per week for treatment. Subjects stood on the WBV platform for 5 repetitions of 30-seconds at with 30-seconds in between bouts. The SV group stretched hamstrings while standing on the WBV during the vibration bouts (at 26 Hz and 4 mm amplitude). The SS group did the same thing except the unit was not turned on. The SQ group stood on the WBV platform in a semi-squat position similar to most WBV training studies, without stretching, but with vibration. The C group stood on the WBV platform in a semi-squat without vibration. Analysis and Results: A mixed models analysis of covariance (ANCOVA) was used while blocking on subjects to analyze data using the statistical program SAS (version 9.1). A Bonferroni correction was used for significance on all post hoc tests (p<.0001). At baseline there were no significant differences between groups for flexibility (see Table 1), showing that each group was similar in flexibility to start. Throughout the treatment period (3 weeks of stretching) both the SS and SV groups had significant increases in flexibility compared to SQ and C. Analysis of the slopes (rate of change) for the treatment period was significantly different between the SV group and all other groups (p<.0001 for all comparisons), showing that the SV group had a greater rate of change than all other groups. For the retention period there was no significant difference between the SV and SS group (p=0.0455), but there was a significant difference between both the SV and SS groups and all other groups (p<.0001 for all comparisons). Conclusion: Stretching during WBV improves flexibility more than static stretching alone and at a faster rate. WBV on its own without stretching does not significantly improve hamstring flexibility.

When the human body is exposed to mechanical vibration, the resonance frequencies of the frequency response functions, such as apparent mass and transmissibility, decrease with increasing magnitude of excitation. For the past two decades, this biodynamic ‘nonlinearity’ has been reported with vertical and horizontal excitation of the body in a wide variety of static sitting and standing postures that require activity from muscles to maintain the stability of the body. There has been speculation, but no experimental evidence, as to the mechanism causing the non-linearity. A review of the literature suggested that either active muscular activity or passive thixotropy of soft tissues is the primary cause of the nonlinearity. The principal objective of this thesis is to identify, and provide experimental evidence of, the primary causal mechanism for the biodynamic nonlinearity. With 0.5 to 20 Hz broadband random vertical vibration at 0.25 and 2.0 ms-2 r.m.s., the first experiment investigated the effect of voluntary periodic upper-body movement and vibration magnitude on the apparent masses of 14 seated subjects. Some movements of the body, such as ‘back-abdomen bending’, significantly reduced the difference in resonance frequency at the two vibration magnitudes compared with the difference during upright static sitting. Without voluntary periodic movement, the median apparent mass resonance frequency was 5.47 Hz at the low vibration magnitude and 4.39 Hz at the high vibration magnitude. With voluntary periodic movement (e.g. back-abdomen bending), the resonance frequency was 4.69 Hz at the low vibration magnitude and 4.59 Hz at the high vibration magnitude. It was concluded that voluntary or involuntary muscular activity, or passive thixotropy of soft tissues, or both muscle activity and thixotropy, could explain the reduction in nonlinearity evident during voluntary periodic movement. The effect of shear history and vibration magnitude on the apparent mass was investigated using 12 subjects in a relaxed semi-supine posture assumed to involve less muscle activity than static sitting and standing. The semi-supine subjects were exposed to two types of vertical (in the x-axis of the semi-supine body) and longitudinal horizontal (z-axis) vibration: (i) continuous random vibration (0.25–20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75, and 1.0 ms-2 r.m.s.); (ii) intermittent random vibration (0.25–20 Hz) alternating between 1.0 and 0.25 ms-2 r.m.s. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 10.35 to 7.32 Hz as the magnitude of vertical vibration increased from 0.125 to 1.0 ms-2 r.m.s., and from 3.66 to 2.44 Hz as the magnitude of horizontal vibration increased from 0.125 to 1.0 ms-2 r.m.s. With the intermittent vibration, the resonance frequency was higher at the higher magnitude (1.0 ms-2 r.m.s.) and lower at the lower magnitude (0.25 ms-2 r.m.s.) than during continuous vibration at the same magnitudes. The response was typical of thixotropy being the primary cause of the nonlinearity. Harmonic distortions in the dynamic force of semi-supine subjects exposed to sinusoidal excitation showed similar dependence on the frequency and magnitude of vibration as previously reported for seated subjects, again suggesting thixotropy as a primary cause of the nonlinearity. In a group of 12 subjects, the apparent mass and transmissibility to the sternum, upper abdomen, and lower abdomen were measured in three supine postures (relaxed semi-supine, lying flat, and constrained semi-supine) during vertical random vibration (0.25 to 20 Hz) at seven vibration magnitudes (nominally 0.0313, 0.0625, 0.125, 0.25, 0.5, 0.75 and 1.0 ms-2 r.m.s.). The motion transmission path that included more soft tissues exhibited a greater nonlinear response. The substantial nonlinearities found in transmissibilities to both the sternum and the abdomen of supine subjects, and previously reported for the transmissibilities of seated and standing subjects, imply that soft tissues at the excitation-subject interface contribute to the nonlinearity. It is concluded that the thixotropy of soft tissues, rather than voluntary or involuntary muscular activity, is the primary cause of the biodynamic nonlinearity seen with varying magnitudes of excitation.

INTRODUCTION: The majority of individuals with chronic spinal cord injury (SCI) experience spasticity, which can often impair function and degrade quality of life. Reports by individuals with SCI suggest that whole body vibration (WBV), as can occur while riding wheelchairs, may trigger spasticity. OBJECTIVES: 1) Examine the influence of wheel design on wheelchair vibration. 2) Develop a system allowing exposure of individuals with SCI to WBV and analysis of muscle activity to identify spasticity. METHODS: 1) A wheelchair wheel comparison study: Vibration acceleration and frequency content produced by wheelchairs equipped with 2 different wheel designs (steel spoked and composite material spoked) were compared as: 1a) 13 subjects with SCI wheeled through an obstacle course simulating a wheelchair user's daily activities 1b) 22 non-SCI subjects wheeled down a ramp and over a vibration inducing obstacle. Vibration acceleration was recorded using 2 accelerometers mounted on the wheelchairs' main axle and footrest. The influence of wheelchair vibration on spasticity was assessed using questionnaires, completed by the SCI subjects. 2) A controlled whole body vibration (CWBV) pilot study: 2 SCI subjects were exposed to 7-12 WBV sessions. Each exposure consisted of a single frequency, lasted 20 seconds, and was repeated on 2 separate days. The WBV was applied using an electrodynamic shaker and the subjects' leg muscles' activity was recorded using an electromyography (EMG) system. Muscle spasms were identified by calculating the ratio between periods of increased muscle activity and the period before exposure to vibration. RESULTS: No statistically significant differences (p=0.05) were found in wheelchair vibration acceleration or frequency content between the 2 tested wheel designs and no clear correlation between wheelchair vibration and spasticity was apparent. The CWBV system was able to apply vibration (-+0.5 Hz, -+0.001 g) and record muscle activity (-+7 mV). The CWBV exposures produced several muscle responses that were considered to be spasms. CONCLUSIONS: The tested composite material spoked wheels do not differ, in vibration performance, from steel spoked wheels. The developed CWBV apparatus appears suitable for studying muscle activity in response to WBV.

Background: Older adults walk more slowly than healthy young adults at fast and normal walking speeds. These age-associated changes in mobility impact upon daily function. A slower gait, for example, may reduce the older adult’s ability to safely cross at traffic intersections due to the time restriction. Recent research has demonstrated whole body vibration (WBV) can improve the strength and power (Roelants, Delecluse & Verschueren, 2004; Russo et al., 2003; Verschueren, Roelants, Delecluse, Swinnen, Vanderschueren & Boonen, 2004) of community dwelling elderly females, and the mobility of nursing home residents (Bautmans, Van Hees, Lemper & Mets, 2005; Bruyere et al., 2005). To date, no published research has examined the impact WBV has on the gait parameters of community dwelling elderly females. The research was conducted in three phases. Phase One – Development of a WBV Platform: This phase outlines the development of a WBV platform (ACUWBV) that was designed and built for this research. A unique aspect of the ACUWBV was the method of adjusting WBV amplitude and therefore intensity. Current WBV technology, using tilting oscillations, requires the individual to increase their stance width. The ACUWBV allowed for the adjustment of WBV amplitude while maintaining the same stance width. The reliability and accuracy of the ACUWBV eccentric cam was measured during this phase of the research. Although an intraclass correlation coefficient of 0.4 was calculated and is considered an indication of low reliability, calculations of typical error (TE -95% error range) for each amplitude indicated the error to be small in the overall precision of the instrument. Specifically, at a frequency of 20 Hz, the expected WBV acceleration ranges for amplitudes of 0.5 mm and 1.0 mm were 7.58 m.s-2 to 8.85 m.s-2 (TE = 0.02 mm) and 16.90 m.s-2 to 17.53 m.s.-2 (TE = 0.01 mm), respectively. Phase Two – Pilot Study: This phase established the response of elderly community-dwelling female fast gait to WBV. Seven elderly female participants attended three WBV sessions per week for three weeks. Participants performed fast walks over an electronic walkway (GAITRite) at the end of each WBV session. A time-series graph displayed a linear increase in stride velocity over the three week intervention period. Conversely, stride time, stance time and double support time exhibited linear decreases. However, stride time (p=0.04) and stance time (p=0.04) were the only variables that exhibited a significant difference. It was concluded that the linear changes in stride velocity, stride time, stance time and double support time warranted further investigation with a larger sample size within a longer intervention period. Phase Three – Major Study: Phase three was an extension of phase two. This WBV intervention study was performed over a twelve week period. Twenty-two elderly female participants were placed in one of two groups. Group one (placebo/WBV; Group; n=12) was exposed to a placebo intervention for the first six weeks followed by a six week WBV intervention. Group two (Group WBV/placebo; n=10) was exposed to WBV for the first six weeks and a placebo intervention for the following six weeks. Group placebo/WBV exhibited no change in stride velocity during the placebo period, but a seven per cent increase during the six week WBV period (p=0.005). The changes in stride velocity coincided with increases in stride length (p=0.017), and reductions in stride time (p=0.007), stance time (p=0.001) and double support time (p=0.001). Group WBV/Placebo demonstrated stride velocity to increase by five per cent during the WBV period. Although the time-series graphs demonstrated improvements in stride velocity to be associated with decreases in stride time, stance time, and double support time, the changes failed to reach significance. Single support time and stride length showed no change over the WBV period. The improvements shown by group WBV/placebo from the first six weeks of WBV were maintained during the six week placebo (detraining) period. In summary, WBV was an effective intervention for enhancing the walking speed of community dwelling elderly female gait. This form of exercise may have positive outcomes on the daily function of elderly females, which in turn may improve their quality of life.

Parkinson’s disease is a chronic degenerative illness, the ultimate causes of which remain largely unknown. This thesis aims to test a new etiological hypothesis: that whole body vibration exposure may be associated with Parkinson’s disease. The thesis comprises three studies relevant to a test of this hypothesis. The first study concerns the methods by which cases of Parkinson’s disease can be defined at a population level and the prevalence of Parkinson’s disease in British Columbia. Levodopa (a drug typically used for Parkinson’s treatment) was increasingly used by people without a Parkinson’s diagnosis between 1996 and 2005, with non-Parkinson’s users outnumbering physician diagnosed cases among women and those under the age of 65 in 2005. These changes in levodopa use could mean that relying on use of levodopa to define Parkinson’s disease cases will be less efficient. The second study developed a method for retrospectively assessing occupational whole body vibration from a detailed interview conducted in a case control sample. I combined self-reported exposure with estimates of vibration intensity (acceleration) derived from the literature to construct metrics of exposure. I concluded that three of the metrics (duration, most intense equipment exposure, and a dose calculation that combined intensity and duration in a cumulative measure after raising vibration acceleration values to the fourth power) captured sufficiently different aspects of occupational exposure for individual tests of their associations with Parkinson’s disease. The third study tested these associations using logistic regression. The metrics were categorized to enable the detection of nonlinear effects. Ever being occupationally exposed to whole body vibration was inversely associated with Parkinson’s disease, as was the lowest category of most intense equipment exposure. However, the highest values of most intense equipment exposure were associated with increased odds of Parkinson’s disease. Effects were strongest when exposures that occurred more recently than 20 years prior to diagnosis were excluded. A protective effect of low intensity vibration could be due to correlation with a confounding protective factor such as physical activity, while an increased risk associated with high intensity exposures could be due to mechanical stress imposed by the repetitive shocks incurred.

Background: Older adults walk more slowly than healthy young adults at fast and normal walking speeds. These age-associated changes in mobility impact upon daily function. A slower gait, for example, may reduce the older adult's ability to safely cross at traffic intersections due to the time restriction. Recent research has demonstrated whole body vibration (WBV) can improve the strength and power (Roelants, Delecluse & Verschueren, 2004; Russo et al., 2003; Verschueren, Roelants, Delecluse, Swinnen, Vanderschueren & Boonen, 2004) of community dwelling elderly females, and the mobility of nursing home residents (Bautmans, Van Hees, Lemper & Mets, 2005; Bruyere et al., 2005). To date, no published research has examined the impact WBV has on the gait parameters of community dwelling elderly females. The research was conducted in three phases.

Whole-Body vibration (WBV) may lead to increased strength gains when coupled with weight and resistance training. It has been reported to increase muscle contraction and power by increasing muscle recruitment. This study set out to see if sessions of WBV following a workout would result in increased strength gains when compared to a control group. Twenty‐four subjects, 12 men and 12 women ages 18-26, with no prior history of musculoskeletal or heart disorders underwent a 3‐week workout routine designed to target and strengthen the knee flexors and extensors. Subjects were sorted into a control or vibe group with the vibe group receiving 5 minutes of post-workout WBV (30 Hz, Amplitude 13 mm). Strength testing was conducted using an isokinetic dynanometer to record knee flexor and extensor torque at the beginning and end of the intervention. A t‐ test was performed for statistical analysis using SPSS to compare the means of the control and vibe group’s strength changes. P values ranges from 0.08 to 0.98, showing no significant differences between the vibe and control group (P > 0.05). It is concluded that in the short term, WBV following resistance training does not improve strength gains in healthy untrained subjects.

Whole Body Vibration (WBV) training is a new addition to the field of Exercise and Sports Science and has been developed for the use in strength and conditioning exercises. With the introduction of this new mode of exercise, the study focused on comparing the strength gaining effect of WBV training versus conventional resistance training. The study was conducted in a descriptive, exploratory manner utilizing a quasi-experimental approach with a three group comparison pre-test-post-test design consisting of an experimental-, comparison- and control group. Convenience and snowball sampling were used to select 43 male and female healthy, sedentary volunteer participants. The research focused on reviewing the contribution that each mode of training offers to increase strength in the upper leg and underlines the important physiological adaptations that the human body undergoes to bring about an increase in muscle strength. Both the whole body vibration and land-based resistance groups trained three times a week over an eight week intervention period. Exercises were performed with progressive increments in the frequency, amplitude and duration for the WBV- and in workload, number of sets and repetitions for the conventional resistance training program. The control group remained sedentary throughout the duration of the study. The dependent variables of peak torque flexion and extension of the knee joint in both legs were analyzed using descriptive and inferential statistics. Analysis of covariance (ANCOVA) was done to determine intra-group differences. Post-hoc analysis in the form of Scheffé’s test was done to determine and compare inter-group differences. Practical significance was indicated by means of Partial eta2 The analysis of the results revealed significant strength increases in both conventional resistance training and WBV for most of the dependent variables, except for peak torque extension, where the WBV group did not increase significantly. Based on these results, it can be concluded that both modes of conventional resistance and whole body vibration increased selected dependent variables for upper leg strength in previously inactive individuals.

BACKGROUND: Whole body vibration (WBV) platforms are currently used as adjunctive training devices for exercise programs, and have been shown to facilitate flexibility. One of the biggest contributing factors to chronic ankle instability (CAI) is the lack of dorsiflexion after lateral ankle sprains and WBV may be an effective way to increase range of motion in this population. PURPOSE: Determine if WBV done concurrently with static stretching (SS) is more effective then SS alone in improving dorsiflexion ROM in subjects with CAI. METHODS: Subjects were divided into 3 groups (control, static stretch, and static stretch and vibrate). Subjects stretched 4 days/wk for 3 wks for 4 sets of 30 seconds alternating 2 different positions to stretch both the soleus and the gastrocnemius. Imposed vibration at 34 Hz 2mm during the stretches for the stretch group. ANALYSIS: Repeated measures ANOVA was performed using SPSS (version 19), with post-hoc Tukey tests as needed (p<.05). RESULTS: In both the straight and bent leg position, a significant group x time interaction was found for dorsiflexion range of motion. Post hoc tests revealed significance in the SV group between pre-tx and post-tx 1 and pre-tx and post-tx 2. No statistical significance was found between post-tx 1 and post-tx 2 in the SV group or at any time in the N or SS group. DISCUSSION: Static Stretching with vibration increases dorsiflexion ROM in subjects with CAI better than static stretching alone.

It is well known that sitting posture is associated with discomfort and a number of musculoskeletal disorders. Seat manufacturers have made great strides toward developing seats for equipment which helped in alleviating the vibration transferring to the lower area of the spine; however, increased neck and head motion resulting from these seat designs may have been overlooked. Many cervical spine studies have been developed to estimate the response of the head and neck; however, these current studies do not take head and neck posture into account. The objective of this work was to study and demonstrate the difference in human biomechanical response to WBV when they use different neck postures. Four head and neck postures: up, down, to the side, and normal (straight forward) were investigated. Ten male subjects with ages ranging from 19 to 28 years were used to test each of the four postures, using the discrete sinusoidal frequencies of 2, 3, 4, 5, 6, 7, and 8 Hz at constant amplitudes of 0.8 m/s^2 RMS and 1.15 m/s^2 RMS in the x-direction (fore-and-aft). Subjects were seated in a rigid seat rigidly mounted to a vibration platform and vibration was generated using a six-degree-of-freedom man-rated shaker table. Subjects were tightly coupled to the seat back, using a neoprene vest and 5 straps, in an effort to reduce any relative motion between the seat and the subject. Subjects reported their head and neck discomfort using the Borg CR-10 scale with each of the postures, and then gave a second discomfort rating for the normal posture for each combination. Motion capture and accelerometer data were used to acquire the motion of the seat, C7 vertebrae, and center-of-head motion. The 3D motion of selected points on the heads and necks of the subjects were acquired using a twelve-camera Vicon motion capture system. Accelerometer data at the head, C7, and seat was used to verify the motion capture data. For the head-down posture, the magnitude of the discomfort function was higher than the normal posture. The head-to-side and head-up postures have shown less discomfort have shown less discomfort in the critical resonance area; however, these postures show roughly the same discomfort as the normal posture in other frequency ranges. In these postures, the subjects are using major neck-back muscles which create a stiffer system and may explain why there is a shift in the second peak in the head-to-side and head-up postures. Interestingly, the head-to-side and head-up postures show a similar trend as the normal posture, however, the peak transmissibility is attenuated. In addition, the subject's average discomfort was lower in this range compared to the normal posture. The head-down posture had the highest transmissibility and discomfort overall and suggests that workers in vibration environments should reduce any head-down postures to avoid unwanted head accelerations and discomfort. This work has demonstrated the importance of considering the head-neck posture in future seat-design studies.

Whole-body vibration (WBV) has been shown to enhance vertical jump performance. The purpose of this study was to determine which WBV intensity has the greatest effect on counter movement jump (CMJ) height and the duration of that affect. Forty-four participants, of varying training statuses, were tested. They participated in > 4 familiarization sessions, to eliminate learning effects. Participants performed a pre-test, followed randomly by one of 5 WBV intensities. Participants performed 3 maximal CMJs immediately, 5, and 10 min following treatment. The best performance was used and calculated as a percentage of the pre-treatment values. A multivariate model (treatment X time X gender) was used to analyze the data. The three-way interaction approached significance (p=0.053) and significance was found for all two way interactions. Females performed the best immediately following the 2.71g treatment (116.9 + 38.4%). Male participants did not increase their performance; however, they may require longer durations of vibration exposure to elicit effects. The differences between males and females may also indicate that the effects of WBV are dependent on strength, stiffness, and/or training levels. Future research should continue to systematically investigate the effects of vibration and participant characteristics on WBV and performance.Keywords: power, frequency, amplitude, training, potentiation, stiffness.
School of Physical Education, Sport, and Exercise Science

Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: A continuous comfort analysis of the whole-body vibration level aboard the S.A. Agulhas II during the 2013-2014 Antarctic voyage was conducted ac- cording BS ISO 2631-1:1997, assuming a standing posture. Just noticeable difference in magnitude testing was conducted on nine subject in the standing posture on a man-rated shaker in the laboratory environment. Two stimuli, a 5 Hz sinusoidal stimulus with a magnitude of 0,5 m.s-2 and a slamming event recoded during the voyage with a magnitude of 0,2 m.s-2 where selected as the stimuli on which to investigate the just noticeable difference thresh-old. The study shows that the vibration level for the duration of the voyage can be considered to be not uncomfortable. The results of the just notice-able difference threshold obtained for the sinusoidal stimulus concur with that found in literature for seated subjects. The just noticeable difference threshold obtained for the ship stimulus does not correlate with the results for the sinu-soidal vibration, implying that there may be an error in the vertical weighting filter provided by the standard or that Webers law does not hold for the just noticeable difference threshold of standing subjects.
AFRIKAANSE OPSOMMING: 'n Deurloopnede gemakanalise van volliggaam vibrasievlakke aanboord die S.A. Agulhas II is uitgevoer. Die analise tydens die 2013-2014 Antarktiese reis is gedoen volgens BS ISO 2631-1 : 1997 vir 'n staande postuur. 'n Net-opmerkbare-verskildrempel toets is uitgevoer op nege vrywillers in 'n staande postuur deur vibrasieherkonstruksie op 'n platform in die laboratorium. Twee stumuli, 'n 5 Hz sinusvorminge stimulus (0,5 m.s-2 r.m.s.) en 'n branderim-pak stimulus (wat tydens die reis opgeneem is, 0,2 m.s-2 r.m.s. is gebruik) om die net-opmerkbare-verskildrempel to ondersoek. Die studie toon dat die vibrasievlakke gedeurende die reis as `nie ongemaklik' geklassifiseer kan word. Die resulte van die net-opmerkbare-verskildrempel verkry vir die sinusvormige stimulus stem saam met bevindinge vir sittende vrywilligers uit die literatuur. Die net-opmerkbare-verskildrempel verkry vir die skip stimulus stem egter nie 'n moonlike onakkuraatheid weegfunksie is wat deur die standard is aanbeveel word of datWeber se wet nie toepaslik is vir die net-opmerkbare-verskildrempel van staande vreywilligers nie.

Background Whole-body vibration (WBV) as a training modality is established in the fields of sport, fitness, rehabilitation, and clinical intervention. WBV exercises are performed thereby while standing on a motor driven oscillating platform device. Therefore, the scientific interest in WBV is a steadily increasing field in sports science and research. It has been shown that WBV training elicits various biological and physiological effects in men. Nevertheless, there are only a small number of studies examining WBV effects on neuromuscular performance of the lower extremities in elderly people. Furthermore, the results of these studies show many discrepancies that may be caused by limitations referring to the different applied training protocols and vibration loads. In addition, there is still a deficit of information for effective but safe recommendations for WBV application for trunk and neck muscles. Therefore, this doctoral thesis deals with three major aspects of WBV as an exercise modality in strength training: (1) the recommendation of optimal vibration loads (VbLs) for the lower extremities as an essential element of the WBV exercise parameters in older adults, (2) the evaluation of these VbLs in a WBV training intervention for elderly people with regard to feasibility and chronic effects on neuromuscular performance of the lower limbs, and (3) the allocation of information for effective but safe advices for VbLs for trunk and neck muscles. These aspects are further specified toward five hypotheses (H1, H2, H3, H4, and H5) by findings and limitations of the current state of literature. Methods The five hypotheses are evaluated within three research papers (studies 1 to 3). The first study (S1) evaluated the optimal VbL determined by the combination of three biomechanical variables (vibration frequency, vibration amplitude, and knee angle) in older adults (H1). Therefore, the neuromuscular activity of the quadriceps femoris and hamstring muscles in 51 healthy subjects were measured during WBV exposure using surface electromyography (EMG). Maximal voluntary contractions (MVCs) were conducted prior to the measurements to normalise the EMG signals. A three-way mixed ANOVA was performed to analyse the different effects of the biomechanical variables on muscle activity. Study 2 (S2) represents a randomised controlled trial to assess the results of S1 implemented in a WBV training protocol and therefore to evaluate the feasibility and effectiveness of a six-week WBV intervention (H2, H3, and H4). A total of 21 subjects was allocated randomly into either a WBV training or control group. While the WBV group completed a six-week WBV training programme the control group was asked not to change their current level of physical activity during the study. Before and after the intervention period, jump height was measured during a countermovement jump (CMJ). In addition, isokinetic knee extension and flexion strength parameters were recorded using a motor-driven dynamometer. The Borg scale for ratings of perceived exertion (RPE scale) was used to evaluate the intensity of WBV exercises within each training session. Changes from pre- to posttest were analysed by a paired sample t-test (within-group comparisons) and independent sample t-test (between-group comparisons). The intention of study 3 (S3) was to analyse the impact of biomechanical variables on neuromuscular activity of different trunk and neck muscles during WBV (H5) filling the lack of information in current literature. Those biomechanical variables were assumed, which current literature suggests as having the lowest risk of negative side effects on the head. Surface EMG was used to record the neuromuscular activity in 28 healthy subjects. EMG signals were normalised to prior measured MVC. Different effects of the biomechanical variables were analysed by an ANOVA for repeated measurements. Results The findings of S1 showed that the biomechanical variables affect the level of neuromuscular activity of thigh muscles in older adults in different dimensions which confirms H1. The maximum levels of muscle activity were significantly reached at high amplitude and high frequency, whereas the factor “knee angle” only significantly affected the quadriceps femoris. Furthermore, WBV led to a higher muscle activation of the quadriceps femoris (74.1 % MVC) than of the hamstring muscles (27.3 % MVC). The main findings in S2 were an increased multi-joint strength performance of the lower limbs during a countermovement jump in the WBV group, whereas values of the control group remained unchanged after the intervention, thus confirming H2. There were no statistically significant differences in isokinetic maximal strength, mean power, or work values in knee extension or flexion in both groups (rejecting H3). In addition, the subjective perceived exertion of the WBV exercises and respective training parameters ranged between moderate rating levels of 7 and 13 of the Borg scale and indicate WBV intervention as a feasible and safe training program for elderly people, which is consistent with H4. Finally, the outcomes of S3 confirmed H5 as the biomechanical variables affect the level of neuromuscular activity of the trunk and neck in different dimensions. The maximum levels of muscle activity were significantly reached at high amplitude and high frequency, while knee angles had similar effects on the VbL. WBV led to a higher muscle activation of the lower back muscles (27.2% MVC) than of neck muscles (8.5 % MVC) and the abdominal muscles (3.6 % MVC). Conclusion A maximised VbL for WBV training in older adults depends on specific combinations of the biomechanical variables (vibration frequency, vibration amplitude, and knee angle). In addition, a WBV training based on this age-specific high VbL is a feasible, suitable and effective training program for elderly people to prevent age-related reduction of muscle performance in the lower extremities. Furthermore, the combination of biomechanical variables recommended in literature as safe for preventing harmful transmissions to the head, only elicit low to moderate muscle activation of the upper body. The findings of this thesis represent fundamental research in the field of WBV and may help to improve further research in this area. Finally, this thesis may help coaches and therapists to enhance the quality of WBV training in practical application
Hintergrund Ganzkörpervibration (Whole-Body Vibration, WBV) hat sich als Trainingsanwendung im Sport-, Fitness, Rehabilitationsbereich und klinischen Bereich etabliert, wobei die Übungen dabei im Stehen auf einer Vibrationsplatte durchgeführt werden. In diesem Zusammenhang ist auch das wissenschaftliche Interesse am Vibrationstraining ein stetig wachsendes Feld in den Bereichen der Sportwissenschaft und Forschung. Bisher konnte gezeigt werden, dass Vibrationstraining verschiedene biologische als auch physiologische Reaktionen beim Menschen hervorruft. Dennoch gibt es nur wenige Untersuchungen, die sich mit den Auswirkungen des Vibrationstrainings auf die neuromuskuläre Leistung der unteren Extremitäten bei älteren Menschen beschäftigen. Des Weiteren weißen die Ergebnisse dieser wenigen Studien viele Widersprüchlichkeiten auf, welche durch die unterschiedlich verwendeten Trainingsvorgaben und Vibrationsbelastungen verursacht sein könnten. Darüber hinaus besteht noch ein großes Defizit an grundlegenden Informationen hinsichtlich effektiver, aber dennoch sicherer Vorgaben in der Anwendung des Vibrationstrainings im Bereich der Rumpf- und Nackenmuskulatur. Vor diesem Hintergrund beschäftigt sich die vorliegende Dissertation mit drei wesentlichen Aspekten des Vibrationstrainings: (1) die Empfehlung von optimalen Vibrationsbelastungen (VbL) als wesentlicher Bestandteil des Vibrationstrainingsplans der unteren Extremitäten älterer Menschen, (2) die Evaluierung dieser VbL anhand einer auf Vibrationstraining basierter Intervention mit älteren Menschen hinsichtlich Durchführbarkeit und Auswirkungen auf die neuromuskuläre Leistung der unteren Gliedmaßen, und (3) Angaben für effektive und sichere VbL für Rumpf- und Nackenmuskulatur bereitzustellen. Mit der Aufarbeitung von Ergebnissen und Defiziten des aktuellen Forschungsstands werden diese Aspekte durch die Formulierung von fünf Hypothesen (H1, H2, H3, H4, and H5) weiter spezifiziert. Methodik Die fünf Hypothesen werden in drei wissenschaftlichen Veröffentlichungen (Studie 1 bis 3) untersucht. Die erste Studie (S1) befasste sich mit der optimalen VbL für ältere Personen (H1), welche durch die Kombination von drei biomechanischen Variablen (Vibrationsfrequenz, Vibrationsamplitude und Kniewinkel) bestimmt wird. Hierzu wurde die neuromuskuläre Aktivität der vorderen und hinteren Oberschenkelmuskulatur von 51 gesunden Probanden unter Vibration mittels Oberflächen-Elektromyografie (EMG) gemessen. Vor den Messungen wurden maximale muskuläre Kontraktionen durchgeführt, um die EMG zu normalisieren. Um die unterschiedlichen Auswirkungen der biomechanischen Variablen zu analysieren wurde eine drei-faktorielle Varianzanalyse durchgeführt. Studie 2 (S2) entspricht einer randomisierten kontrollierten Studie, welche die Ergebnisse aus S1 in einem Trainingsplan verwendet, um die Durchführbarkeit und Effektivität eines sechs wöchigen Vibrationstrainings zu untersuchen (H2, H3, und H4). Hierfür wurden 21 Probanden zufällig einer Vibrationstrainings- oder einer Kontrollgruppe zugeteilt. Während die Vibrationsgruppe ein sechs wöchiges Vibrationstraining absolvierte, wurden die Teilnehmer der Kontrollgruppe gebeten ihre körperliche Aktivität während des Studienzeitraums nicht zu verändern. Vor und nach dem Untersuchungszeitraums wurde die Sprunghöhe während eines „countermovement jump“ (CMJ) erfasst. Weiterhin wurden isokinetische Kraftmessgrößen der Kniegelenkbeugung und –streckung an einem Dynamometer ermittelt. Die Borgskala zur Erfassung des subjektiven Belastungsempfindens wurde eingesetzt, um die Intensität der Übungen des Vibrationstrainings innerhalb einer Trainingseinheit zu messen. Veränderungen der Messgrößen zwischen Eingangs- und Abschlusstest wurden statistisch mit einem t-Test für abhängige (innerhalb einer Gruppe) und einem t-Test für unabhängige Stichproben (zwischen den Gruppen) untersucht. Ziel der dritten Studie (S3) war es den Einfluss der biomechanischen Variablen auf die muskuläre Aktivierung verschiedener Rumpf- und Nackenmuskeln (H5). Hierzu wurden solche biomechanische Variablen ausgesucht, welche laut derzeitigem Wissensstand jeweils das geringste Risiko von Nebenwirkungen für den Kopf ausüben. Mittels Oberflächen-EMG wurde die muskuläre Aktivität von 28 Probanden erfasst. EMG Signale wurden zu vorangegangenen MVC Messungen normalisiert. Die Unterschiedlichen Effekte der biomechanischen Variablen wurden mittels einer Varianzanalyse für Messwiederholungen analysiert. Ergebnisse Die Ergebnisse von S1 konnten zeigen, dass die biomechanischen Variablen den neuromuskulären Aktivierungsgrad der Oberschenkelmuskulatur bei älteren Personen unterschiedlich beeinflussen und somit H1 bestätigen. Der höchste Grad der Aktivierung wurde deutlich mit einer großen Amplitude und hohen Frequenz erreicht, wobei der Kniewinkel ausschließlich die vordere Oberschenkelmuskulatur beeinflusst. Zudem, führte der Vibrationseinfluss zu einer größeren Muskelaktivität der Oberschenkelvorderseite (74.1 % MVC) als der –rückseite (27.3 % MVC). Die Resultate von S2 hinsichtlich des CMJ Tests bestätigen H2, da es in der Vibrationstrainingsgruppe zu einer gesteigerten gelenksübergreifender Kraftleistung in den Beinen kam, aber keine Veränderungen in der Kontrollgruppe feststellbar waren. Hingegen kam es in keiner Gruppe zu statistisch signifikanten Veränderungen der isokinetischen Messgrößen (Maximalkraft, Kraftleistung, Muskelarbeit), wodurch H3 abgelehnt wird. Das subjektive Belastungsempfinden der Übungen und des Belastungsgefüges des Vibrationstrainings liegt zwischen moderaten Bewertungsstufen von 7 bis 13 der Borgskala und weist daraufhin, dass Vibrationstraining ein praktikables und sicheres Übungsprogramm für ältere Menschen ist und somit H4 bestätigt. Die Ergebnisse von S3 konnten H5 bestätigen, da die biomechanischen Variablen den neuromuskulären Rumpf- und Nackenmuskulatur unterschiedlich beeinflussen. Der höchste Grad der Aktivierung wurde deutlich mit einer großen Amplitude und hohen Frequenz erreicht, wobei der Kniewinkel sich ähnlich auf die VbL auswirkt. Der Vibrationsstimulus führte zudem zu einer höheren Aktivierung der unteren Rückenmuskulatur (27.2% MVC) als der Nacken- (8.5 % MVC) und Bauchmuskulatur (3.6 % MVC). Schlussfolgerungen Die maximale muskuläre Belastung älterer Personen in einem Vibrationstrainings hängt von bestimmten Kombinationen der biomechanischen Variablen (Vibrationsfrequenz, Vibrationsamplitude und Kniewinkel). Zudem ist ein Vibrationstraining, das auf altersspezifischen Vibrationsbelastungen basiert ein machbares, angemessenes und effektives Trainingsprogramm für älteren Menschen, um einem altersbedingten Abnehmen der muskulären Leistungsfähigkeit vorzubeugen. Weiterhin führt die Verbindung von biomechanischen Variablen, welche laut bisherigem Forschungsstand als sicher gegen schädliche Vibrationsübertragungen zum Kopf gelten, nur zu leichten bis moderaten Muskelaktivierung im Oberkörper. Die Ergebnisse dieser Dissertation liefern einen Beitrag zur Grundlagenforschung auf dem Gebiet des Vibrationstrainings und können weiteren Forschungsarbeiten hilfreich sein. Darüber hinaus kann diese Arbeit helfen die Qualität von Vibrationstrainingsangeboten zu verbessern und somit zum praktischen Nutzen beitragen

Studies of human response to whole-body vibration, such those encountered in heavy machinery and ground and aerial transportation, have highlighted the critical role of the head-neck posture of seated human occupants and the role of the transport system of a supine human on the severity of the transmitted vibration to the human body. Novel passive and muscle-based models are introduced in this work to predict the biodynamical response of the human under whole-body vibration in seated and supine postures. Planar and three-dimensional models representing the human head-neck system under different seated postures and fore-aft and multiple-axis whole-body vibration are first introduced. In these models, the head-neck system is represented by rigid links connected via spring-damper components representing the soft-tissue and connecting elements between the bones. Additional muscle components are added to some models. The muscle components comprise additional mass, spring, and damper elements arranged in a special order to capture the effect of changes in the displacement, velocity, acceleration, and jerk. The results show that the proposed models are able to predict the displacement and acceleration of the head under different vibration files, with the muscle-based models showing better performance than the passive models. The second set of models is introduced in this work to investigate the effect of the underlying transport system conditions on the response of supine humans under vertical and multiple-axis whole-body vibration. In these models, the supine human body is represented by three rigid links representing the head, torso/arms, and legs. The links are connected via rotational and translational joints, and therefore, it is expected that the models can capture the coupling effects between adjacent segments. The joints comprise translational and rotational spring-damper components that represent the soft tissue and the connecting elements between the segments. The contact surfaces between the supine human and the underlying transport system were modeled using spring-damper elements. Two underlying transport systems were considered, including a rigid support and a long spinal board attached to a military litter. The results showed that the proposed models were able to predict the effect of the transport systems on the human response under different vibration conditions.

Whole body vibration (WBV) is a mode of exercise by which an individual stands on a vibration platform that may be oscillating and therefore creating vertical displacement which affects gravitational forces acting upon the whole body. Manipulations of platform amplitude or frequency can affect the rate of change of the WBV (i.e. acceleration) acting upon an individual. The specific influences of frequency or amplitude, however, are unknown. The aim of the study, therefore, was two fold; (1) to identify chronic WBV effects of neuromuscular performance within a community dwelling older adult sample, and; (2) to identify WBV methods that would elicit chronic neuromuscular performance changes within such a sample. The study incorporated a randomised controlled experimental design to examine the aim. Seventy-three community dwelling older adults freely consented to the requirements of the study (mean age = 72.0 years). Neuromuscular performance was quantified with the 5-Chair Stands test, the Timed Up and Go (TUG) test and the Tinetti test. Health Related Quality of Life (HRQOL) was qualified with the SF-36 Health Survey. A six week WBV intervention significantly changed the quantifiers of neuromuscular performance in a community dwelling older adult sample. The WBV intervention significantly reduced time taken to complete the 5-Chair Stands test (p <.05) and the TUG test (p <.05). The six week WBV intervention significantly improved Tinetti test scores (p <.05). The six week WBV intervention significantly improved all components of HRQOL. For the 5-Chair Stands test, a three WBV sessions per week intervention elicited significantly larger (p <.05) neuromuscular performance gains than a two WBV sessions per week intervention in the target sample. For the TUG test, a three WBV sessions per week intervention elicited significantly larger (p <.05) neuromuscular performance gains than a zero and one WBV session per week intervention in the target sample. A significant difference (p <.05) was found between pre-test and post-test Tinetti test scores for all WBV intervention groups. There was an insignificant difference (p >.05) found within the control group of community dwelling older adults for the Tinetti test. Detraining effects were observed three weeks after the cessation of the six week WBV intervention for the three WBV sessions per week group. Neuromuscular performance reduced after the detraining period. Vibration platform dynamics (manipulated frequency and controlled amplitude) showed that gravitational forces created by the WBV were safe since no injuries were associated with the intervention and since participant compliance was 100% during the six week WBV intervention. The methods of this study showed a chronic WBV intervention to be a safe and easily administered exercise to improve neuromuscular performance and HRQOL of a community dwelling older adult sample. Specifically, WBV could be used as a safe and effective tool to improve aspects of normal daily function such as body balance and gait speed.

There are many factors that can influence the effectiveness of any risk management strategy, in the case of whole-body vibration exposure many problems are faced with the quantification of risk, measurement of risk and subsequent risk reduction. The quantification of vibration effects is equally as complex as the quantification of vibration itself. Exposure to whole-body vibration (WBV) causes a distribution of motions and forces within the human body and to complicate matters the transmission of vibration to the body is also dependent on body posture. To-date there has been little attempt to accurately reflect many of the typical postures and vibration environments experienced by operators of earth moving machines in a laboratory setting. The overall aim of the thesis was to determine the variability between humans, machines and task environments in order to provide knowledge to inform improvements in methods of risk management for whole-body vibration exposure. The field measurement phase of the research focused on characterising features of whole-body vibration exposure among operators of earthmoving machines throughout a range of industry sectors. Some of the biggest industries; coal mining, quarries, and construction were targeted to obtain data on the types of machines for which very little was previously available. Research was carried out under real operating conditions to investigate the nature of occupational exposure to whole-body vibration and to determine the causes of variability between measurements. The laboratory phase of the research simulated the conditions of the 'real working environment' observed in the field study in order to examine how twisted non-neutral postures could influence the biomechanical, performance and workload responses of humans. The machines with the greatest vibration emission were generally those that spent most of their time tracking. The worst machine for vibration exposure was a challenger 85D tracked tractor towing a 'hex' attachment. Operators of this machine would exceed the EU Physical Agents Exposure Limit Value in about 2.5 hours. The next most severe earth moving machines were bulldozers and tracked loaders and with long working hours typically observed in industry some of these machines would also exceed the ELV in a working day. The influence of variability between work cycles was found to be a particular problem for the bulldozer and excavator machines, variation between work cycles exceeded the 25% variance limit criteria. If these machines were targeted for a WBV health risk assessment then the measurement durations will need to take account of this variation in the extrapolation to an 8-hour exposure. The operators of these tracked machines were also found to adopt non-neutral twisted postures during reversing manoeuvres. The twisted posture adopted by the bulldozer and tracked loader operators was recreated in the laboratory. Findings demonstrated that operators are likely to be putting their necks in a vulnerable position in the twisted posture due to the large increase in rotational movement at the head during exposure to vibration. Decrements in reaction time performance and increases in workload were also found while individuals were sat in a twisted posture and exposed to vibration.

Whole body vibration (WBV) is a mode of exercise by which an individual stands on a vibration platform that may be oscillating and therefore creating vertical displacement which affects gravitational forces acting upon the whole body. Manipulations of platform amplitude or frequency can affect the rate of change of the WBV (i.e. acceleration) acting upon an individual. The specific influences of frequency or amplitude, however, are unknown. The aim of the study, therefore, was two fold; (1) to identify chronic WBV effects of neuromuscular performance within a community dwelling older adult sample, and; (2) to identify WBV methods that would elicit chronic neuromuscular performance changes within such a sample. The study incorporated a randomised controlled experimental design to examine the aim. Seventy-three community dwelling older adults freely consented to the requirements of the study (mean age = 72.0 years). Neuromuscular performance was quantified with the 5-Chair Stands test, the Timed Up and Go (TUG) test and the Tinetti test. Health Related Quality of Life (HRQOL) was qualified with the SF-36 Health Survey. A six week WBV intervention significantly changed the quantifiers of neuromuscular performance in a community dwelling older adult sample. The WBV intervention significantly reduced time taken to complete the 5-Chair Stands test (p .05) found within the control group of community dwelling older adults for the Tinetti test. Detraining effects were observed three weeks after the cessation of the six week WBV intervention for the three WBV sessions per week group. Neuromuscular performance reduced after the detraining period. Vibration platform dynamics (manipulated frequency and controlled amplitude) showed that gravitational forces created by the WBV were safe since no injuries were associated with the intervention and since participant compliance was 100% during the six week WBV intervention. The methods of this study showed a chronic WBV intervention to be a safe and easily administered exercise to improve neuromuscular performance and HRQOL of a community dwelling older adult sample. Specifically, WBV could be used as a safe and effective tool to improve aspects of normal daily function such as body balance and gait speed.

Acute exposure to vibration has been suggested to produce transient increases in muscular strength (1,2,8), vertical jump displacement (4,8), and power output (2,6,7) recorded while performing various tasks. It has been hypothesized that the reported acute vibration induced increases in performance occur as a result of alterations in neuromuscular stimulation (1,3,4). Specifically, most studies have ascribed the observed improvements to the likeliness of Whole Body Vibration (WBV) in producing a “tonic vibration reflex” (TVR) in which the primary nerve endings of the Ia afferents of the muscle spindle are activated. This is thought to result in the excitation of the alpha-motor neurons and activation of the extrafusal fibers (4) which likely leads to a greater synchronization of motor units as a result of homonymous motor unit contraction. However, not all investigations report improvements in muscular strength (4), vertical jump (7), and power production in response to acute vibration (4). While the current body of scientific knowledge offers conflicting evidence on the effectiveness of WBV in augmenting neuromuscular performance it is possible that WBV may result in alterations to specific aspects of the force-time curve during the performance of a maximal isometric contraction. Therefore, the primary purpose of this investigation was to examine the effects of WBV performed using 30 Hz frequency and 2-4 mm amplitude on the force-time curves of an isometric mid-thigh pull.

The identification of the physical parameters (mass, stiffness, and damping) of structural, mechanical, and biomechanical systems is a major challenge in many applications, especially when dealing with old systems and biological systems with heavy damping and where environmental noises are presented. This work presents a novel methodology called eigenvector phase correction (EVPHC) to solve for the physical parameters of structural and biomechanical systems even with the existence of a significant amount of noise. The method was first tested on structural/mechanical systems and showed superior results when compared with an iterative method from the literature. EVPHC was then developed and used to identify the physical parameters of supine humans under vertical whole-body vibration. Modal parameters of fifteen human subjects, in the supine position, were first identified in this work using experimentation under vertical whole-body vibration. EVPHC was then used to solve an inverse modal problem for the identification of the stiffness and damping parameters at the cervical and lumbar areas of supine humans. The results showed that the resulting physical parameters were realistically close to those presented in the literature. The proposed human model was able to predict the time histories of the acceleration at the head, chest, pelvis, and legs very closely to those of the experimental measured values. A scaling methodology is also presented in this work, where an average human model was scaled to an individual subject using the body mass properties.

The aim of this study was to determine the effect of whole body vibration training on selected health and fitness parameters, including: blood glucose levels, blood pressure, anthropometric profile, muscular flexibility, muscular strength, muscular endurance, and aerobic endurance of persons with diabetes mellitus type II. The study was conducted in a descriptive, explorative manner utilizing a quasiexperimental design with an equistatic approach, employing match-pair design to participant grouping. The experimental design was a non-randomized two-group pre- and post-test design, in which approximately 16 male and female participants, who were chosen through convenience and snowball sampling with diabetes mellitus type II, completed the study. Pre- and post-test analysis was performed at the Biokinetics and Sport Science Unit. The whole body vibration training (experimental) group, trained three times a week for a period of ten weeks, performing exercises on the vibration platform with progressive increments in the intensity, duration, and number of the exercises. The control group remained sedentary throughout the intervention period. The dependant variables were analyzed using descriptive statistics. ANOVA was done to determine pre- and post-test differences for both the experimental and control groups for all the variables. Post-Hoc analysis was done to determine and compare differences which may have existed between the experimental and control groups, with practical significance being determined by Cohen’s D analysis. The analysis of the results revealed significant improvements in systolic blood pressure, muscular strength, muscular endurance, and aerobic endurance.

Decompression sickness (DCS) is a risk associated with high-altitude aviation and diving. During these activities, decompression may lead to supersaturation of inert gas dissolved in bodily tissues and subsequently activate bubble formation in various bodily tissues, including in venous blood, known as venous gas emboli (VGE). It has been shown that the amount of VGE detected during and after decompression is linked to the risk of developing DCS. Thus, lowering the incidence of VGE would lower the risk of developing DCS. Previous studies have demonstrated that a session of whole-body vibration prior to a diving session is effective in lowering VGE formation. However, no study has investigated the effect of whole-body vibration on high-altitude-induced VGE. For the present study, 3 participants were recruited. The subjects performed on separate days (interspaced by 48 h) and in a randomised manner, three different preconditioning strategies: (A) 40-min seated rest, (B) 30-min seated rest followed by 150 knee squats performed over a 10 min period and (C) 30-min whole-body vibration (40 Hz) proceeded by a 10 min seated rest. Thereafter, subjects were exposed to an altitude of 24,000 ft continuously for 90 min, whilst laying in a supine position and breathing a normoxic gas mixture (PIO2 = 21 kPa). Heart rate (HR), cardiac output (CO) and stroke volume (SV) were monitored throughout the high-altitude exposure. Every 5 min, VGE prevalence was assessed ultrasonically and graded according to the Eftedal-Brubakk 5-point scale. In addition, every 15 min, subjects were asked to perform three fast, unloaded knee-bends while in their left-side horizontal recumbent position, with VGE prevalence being estimated both before and after the three knee-bends. The control strategy was associated with a higher VGE scores (2.7 ± 1.2) compared to vibration (1.0 ± 1.0) and squats (1.3 ± 0.6) strategies. VGE appeared earlier during the control strategy (35 ± 23 min) compared to the vibration (65 ± 31 min) and squats (50 ± 17 min) strategies. A strong negative correlation was only observed in the control strategy between VGE and CO (r = -0.63) and SV (r = -0.64). This study demonstrated that whole-body vibration is the most effective preconditioning strategy in lowering the amount of high-altitude-induced VGE compared with 40-min of seated-rest and 150 knee squats performed over a period of 10 min.
Att drabbas av dekompressionssjuka (DKS) utgör en risk vid såväl höghöjdsflygning som dykning. I samband med dessa aktiviteter, kan dekompression leda till övermättnad av inert-gas löst i kroppens vävnader, vilket i sin tur kan leda till bubbelformation i olika vävnader, inklusive i venblodet, där bubblorna benämns venösa gasembolier (VGE). Det har visats föreligga ett samband mellan mängden VGE som uppmäts under och efter dekompression och risken att utveckla DKS. Således kan det antas att en minskad incidens av VGE är förknippad med minskad risk att utveckla DKS. Tidigare undersökningar har påvisat att en period med helkroppsvibration före dykning påtagligt minskar bildningen av VGE. Hittills har man dock inte undersökt om helkroppsvibration påverkar höghöjdsinducerade VGE. I föreliggande undersökning, medverkade tre försökspersoner. De exponerades vid separata tillfällen (med 48 timmars mellanrum), och i olika ordningsföljd, för tre prekonditioneringsstrategier: (A) 40 min sittande vila, (B) 30 min sittande vila följt av 150 djupa knäböjningar som genomfördes under en 10-minutersperiod och (C) 10 min sittande vila följt av 30 min helkroppsvibration (40 Hz). Därefter exponerades försökspersonerna för en simulerad höjd motsvarande 24,000 fot ö.h. kontinuerligt under 90 min, under det att de i liggande ryggläge andades en normoxisk gasblandning (inspiratoriskt syrepartialtryck = 21 kPa). Hjärtfrekvens (HF), hjärtminutvolym (HMV) och hjärtats slagvolym (SV) mättes kontinuerligt under höghöjdsexponeringen. Var femte min bedömdes prevalensen av VGE med hjälp av ultraljudsteknik och en 5-gradig skattningsskala. Var femtonde min genomförde försökspersonerna 3 obelastade knäböjningar, liggande i vänster sidoläge, varvid VGE-prevalensen bedömdes såväl före som efter knäböjningarna. Kontrollbetingelsen (A) framkallade högre VGE-nivå (2,7 ± 1,2) än vibrationsbetingelsen (B; 1 ± 1) och knäböjbetingelsen (C; 1,3 ± 0,6). VGE uppträdde tidigare under kontrollbetingelsen (35 ± 23 min) än i vibrations- (65 ± 31 min) och knäböj-betingelserna (50 ± 17 min). Starka negativa samband påvisades mellan VGE och CO (r = -0,63) respektive SV (r = -0,64). Således visade föreliggande undersökning att helkroppsvibration.

As populações idosas institucionalizadas são propensas a doenças e invalidez. Estes são cuidados por profissionais de saúde que lhes permitem melhorar a realizar as atividades no dia-a-dia. Fisiologicamente, os idosos à medida que envelheciam, diminuem a densidade mineral óssea (BMD), força muscular e aptidão física. Neste estudo, o objetivo foi o de determinar o efeito de um programa de exercício vibratório de baixa frequência de três meses. Oito sujeitos institucionalizados foram distribuídos de forma não aleatória pelo grupo de exercício (GE) vibratório (5 indivíduos; 82,80 ± 5,07 anos) e no grupo de controlo (CON) grupo (3 indivíduos; 85,33 ± 10,97 anos). O GE vibratório efetuou ao longo de três meses um programa exercício vibratório recíproco, numa posição ereta com os joelhos semi-flexionados, com uma frequência de12,6 Hz, amplitude 3mm, efetuando 6 séries por sessão, com um período de descanso de um minuto de intervalo, e com a frequência semanal de 3 vezes. O grupo CON não alterou a sua rotina diária. As variáveis estudadas foram: a densidade mineral óssea (DMO) no quadril direito e corpo total utilizando um densitómetro de duplo feixe de raios-X (DEXA); força máxima e potência média em ação muscular concêntrica na extensão e flexão do joelho com velocidades angulares de 60 ° / s e 180 ° / s, utilizando um dinamômetro isocinético; aptidão física, mais em concreto a distância percorrida em 6 minutos a andar, flexão de braço, sentar e alcançar, alcançar atrás das costas, levantar caminhar e sentar. No início do estudo, verificou-se diferenças estatisticamente significativas entre o GE e o COM na variável peso (P = 0,043). Após os 3 meses de intervenção, o grupo exercício vibratório diminuiu significativamente (6%) a DMO no triângulo de wards comparativamente com o grupo CON que aumentou 4% (P <0,05). Não se verificaram alterações significativas na força máxima e potência média em ambos os grupos. Verificaram-se efeitos induzidos pelo treino no teste da caminhada de 6 minutos, e no teste de alcançar atrás das costas, tendo sido melhor no GE em relação ao grupo CON (P = 0,024 para o teste de caminhada de 6 minutos e P = 0,043 para alcançar atrás das costas). Não se verificaram mais alterações significativas nas outras variáveis estudadas em qualquer um dos grupos. No sujeitos idosos institucionalizados, três meses de um programa de exercício vibratório de baixa frequência, obteve efeito sobre a aptidão física; Abstract- Effect of Low Frequency Whole Body Vibration for elderly living in Nursing homes, Body Composition and Physical Fitness Elderly population in nursing rehabilitation center is prone to diseases and disability even if they are well taken cared-off by health professionals to help function in daily activities. Physiologically, elderly as they aged there bone mineral density (BMD), muscle strength and physical fitness will normally decline. In this study, the objective is to determine the effect of 3-month Low frequency Whole Body Vibration (WBV) after the intervention was withdrawn for 3 months. Eight nursing home residents were non-randomly assigned to WBV group (5 subjects; 82.80±5.07 years) and Control (CON) group (3 subjects; 85.33±10.97 years). The WBV group underwent 3 months of semi-flexed standing exercise in reciprocal vibratory machine at 12.6 Hz, 3mm amplitude, 6 sets per session with 1 minute interval rest period for 3 times a week while the CON group continues to their daily routine with no vibration. Outcome measures were right hip and whole body BMD (g.cmˉ²) using Dual-energy X-ray Absorptiometry (DEXA), maximal strength and average power concentric isokinetic knee extension and flexion at 60°/s and 180°/s by isokinetic dynamometer and physical fitness measures such as 6 minute walk test, arm curl test, chair sit and reach, back scratch and 8 foot up and go. At baseline, WBV and CON group were statistically significant difference on their weight status (P=0.043). After vibration was withdrawn for 3 months, WBV group significantly decreased (6%) in BMD wards triangle compared to CON group increased by 4% (P<0.05). No significant changes in maximal strength and average power on both groups. There are training-induced changes in 6 minute walk test and Back scratch were better compared to CON group (P=0.024 for 6 minute walk test and P= 0.043 for back scratch). No other significant changes were observed in both groups. In nursing rehabilitation center residents, 3 months low frequency WBV exercise has effect on physical fitness.

Vehicle occupants are typically exposed to unpleasant whole-body vibration (WBV) for extended period of time. It is well known that the transmission of unwanted vibration to the human body can lead to fatigue and discomfort. Moreover, the unwanted vibration normally distributed in the low-frequency range has been found as the main risk factor for lower back pain and lumbago, which seriously affect the health and working performance of occupants. Thus vibration cancellation on seats has attracted considerable interest in recent years. So far, for most vehicle seats, vibration isolation is achieved passively by using seat cushions and conventional energy absorbers, which have very limited performance in the low-frequency range. The work presented in this thesis forms a successful development and experimental study of an active seat and control algorithm for occupants’ WBV reduction under low frequency excitations. Firstly, a modelling study of the seat human subjects (SHS) and an extensive experimental measurement of the vibration transmissibility of a test dummy and vehicle seat are carried out. The biodynamic responses of SHS exposed to uncoupled vertical and fore-and-aft WBV is modelled. A comparison with the existing models is made and the results show that an improved fit with the aggregated experimental data is achieved. Secondly, an active seat is developed based upon the observations and understanding of the SHS and seat system. The characteristics of the active seat dynamics are identified through experimental tests found suitable for the development of an active seat to attenuate the vibration experienced by vehicle occupants. The vibration cancellation performance of the active seat is initially examined by feedforward plus proportional-integral (PI) control tests. Through these tests, the effectiveness of the actuators control authority is verified, but the limitations are also revealed. Because the active seat system is subject to non-linear and time-varying behaviour, a self-tuning fully adaptive algorithm is a prime requirement. The Filtered-x Least-Mean-Square (FXLMS) algorithm with the Fast-block LMS (FBLMS) system identification technique is found suitable for this application and is investigated through experimental tests. Substantial vibration reductions are achieved for a variety of input vibration profiles. An excellent capability of the active seat and control system for efficiently reducing the vibration level of seated occupants under low-frequency WBV is demonstrated.

Musculoskeletal disorders are common among professional driver groups. Ergonomic risk factors at work are often suggested as causative, aggravating or preserving. The general aim with this thesis is to investigate the association between musculoskeletal disorders and physical exposure with special with special focus on whole-body vibration (WBV), among professional drivers of all-terrain vehicles (ATVs). Drivers of ATVs are expsosed to high magnitudes of WBV and shock. This thesis included drivers of forest machines, snowgroomers and snowmobiles. A cross-sectional study revealed that ATV drivers had an increased risk of musculoskeletal symptoms in the neck-shoulder and thoracic regions, even after adjusting for age, smoking habits and psychosocial stress. Prevalence rates were in the range of 1.5-2.9 (CI:1.2-5.2) compared to an age-matched group from the general population. No group of ATV drivers had a significantly increased risk of low back pain. Trend analysis showed no association between symptoms and exposure time. A clinical investigation of a subgroup found that it was for ATV drivers with neck pain to have assymetrical and focal neuropathies, pure or in mix with a nociceptive disorder, in the neck and upper extremities (47-79%), which was in contrast to referents with neck pain who had more nociceptive disorders (27% prevalence of neuropathy). Two studies measured characteristics of seated WBV exposure in forest machines (forwarders), snowgroomers and snowmobiles. The magnitudes of WBV in ATVs, measured and analyzed according to ISO 2631-1, were between 0.5-3.5 m/s2 (frequency weighted vector sum), which was considered high compared to limits suggested by the international standard ISO 2631-1 and the physical agent directive from the Euoropean Union (0.5 m/s2, rms). Drivers of ATVs were exposed to horizontally directed WBV and shocks. Non-neutral neck postures are ergonomic risk factors that occured infrequently and with short duration. The magnitude of seated WBV in forwarder vehicles varied substantiálly depending on model, terrain condition and driver. This may result in different conclusions regarding health risk assessments. The main conclusion from this thesis is that musculoskeletal symptoms and disorders in the neck and upper extremities, among drivers of ATVs, may be a result of long-time exposure to shock-type and horisozontally oriented seated WBV.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.
In this document the reduced order simulation and optimisation of the passive suspension systems of a locally produced forty ton articulated dump truck is discussed. The linearization of the suspension parameters were validated using two and three dimensional MATLAB models. A 24 degree-of-freedom, three dimensional ADAMS/VIEW model with linear parameters was developed and compared to measured data as well as with simulation results from a more complex 50 degree-of-freedom non-linear ADAMS/CAR model. The ADAMS/VIEW model correlated in some aspects better with the experimental data than an existing higher order ADAMS/CAR model and was used in the suspension system optimisation study. The road profile over which the vehicle was to prove its comfort was generated, from a spatial PSD (Power Spectral Density), to be representative of a typical haul road. The weighted RMS (Root Mean Squared) and VDV (Vibration Dose Value) values are used in the objective function for the optimisation study. The optimisation was performed by four different algorithms and an improvement of 30% in ride comfort for the worst axis was achieved on the haul road. The improvement was realised by softening the struts and tires and hardening the cab mounts. The results were verified by simulating the optimised truck on different road surfaces and comparing the relative improvements with the original truck’s performance.