Journal articles on the topic 'Emu muscle'
To see the other types of publications on this topic, follow the link: Emu muscle.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Emu muscle.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Patak, A., and J. Baldwin. "STRUCTURAL AND METABOLIC CHARACTERIZATION OF THE MUSCLES USED TO POWER RUNNING IN THE EMU (DROMAIUS NOVAEHOLLANDIAE), A GIANT FLIGHTLESS BIRD." Journal of Experimental Biology 175, no. 1 (February 1, 1993): 233–49. http://dx.doi.org/10.1242/jeb.175.1.233.
Full textAbstract:
The emu is a giant flightless bird, capable of sustained high-speed running. Anatomical, histochemical and biochemical properties of the lower leg muscles used to power running were investigated. The gastrocnemius is the largest muscle in the emu leg. It has a short inelastic tendon and contains only fast fibres. It is the major power-producing muscle of the lower leg, with a greater capacity than the digital flexor muscles for bursts of high work output. In marked contrast, the digital flexors have long elastic tendons and contain both fast and slow muscle fibres. It is proposed that these muscles, rather than the gastrocnemius, are responsible for maintaining posture and that they facilitate elastic energy storage and retrieval in their tendons during running. In comparison with equivalent muscles of flying and diving birds, emu lower leg muscles display features consistent with greater power output during both short burst and endurance running. The emu muscles are more massive relative to body size, and the gastrocnemii of other birds invariably contain slow fibres This study illustrates some of the similarities as well as differences between muscles used during flying and running. Capacities for sustained high-energy work appear to be similar in flying birds and running emus as judged from (1) the muscle masses used during locomotion when expressed as a proportion of total body mass and (2) muscle fibre type compositions and their potential for fuel catabolism. The lower creatine kinase activity in emu leg muscles could be attributed to higher energy demands during the initial stages of lift-off for flight.
2
Stirling, R. V., and D. Summerbell. "Specific guidance of motor axons to duplicated muscles in the developing amniote limb." Development 103, no. 1 (May 1, 1988): 97–110. http://dx.doi.org/10.1242/dev.103.1.97.
Full textAbstract:
The effect of alteration of limb pattern upon motor axon guidance has been investigated in chick embryos. Following grafting of the zone of polarizing activity (ZPA) into the anterior margin of the early limb bud, limbs develop with forearms duplicated about the anteroposterior axis. The position of motoneurones innervating the duplicated posterior forearm extensor EMU was mapped by retrograde transport of horse radish peroxidase (HRP). The motor pool labelled from injection into the anteriorly duplicated EMU muscle is consistently similar to that supplying the posterior EMU muscle on the unoperated side of the embryo. In those cases where the axons are well filled, their trajectories from the injection site are observed to change position within the radial nerve to specifically innervate the duplicated muscle. The axons modify their trajectories proximal to the level of limb duplication in a region where there is no change in the pattern of overt differentiation of the limb cells. This suggests that axons may use a cell's positional value to navigate and provides significant support for the theory of positional information.
3
Suman, S. P., P. Joseph, S. Li, C. M. Beach, M. Fontaine, and L. Steinke. "Amino acid sequence of myoglobin from emu (Dromaius novaehollandiae) skeletal muscle." Meat Science 86, no. 3 (November 2010): 623–28. http://dx.doi.org/10.1016/j.meatsci.2010.04.041.
Full text
4
Hulbert, A. J., S. Faulks, W. A. Buttemer, and P. L. Else. "Acyl composition of muscle membranes varies with body size in birds." Journal of Experimental Biology 205, no. 22 (November 15, 2002): 3561–69. http://dx.doi.org/10.1242/jeb.205.22.3561.
Full textAbstract:
SUMMARYThe acyl composition of phospholipids from pectoral muscle of eight species of birds, ranging in size from the 13 g zebra finch to the 34 kg emu, were measured and combined with recent published results for a 3 g hummingbird. This represents an approximately 11000-fold range in body mass. Muscle phospholipids, and thus muscle membrane bilayers, from birds had a relatively constant unsaturated acyl chain content of 62% but exhibited a significant allometric decline in unsaturation index (number of double bonds per 100 acyl chains) with increasing body mass. There was a significant allometric increase in the percentage of mono-unsaturates and a significant allometric decline in the percentage of n-3 polyunsaturates with increasing body mass,whilst there were no significant allometric trends in either percentage of n-6 or percentage of total polyunsaturates in bird muscle. The relative content of the highly polyunsaturated docosahexaenoic acid (22:6 n-3) showed the greatest scaling with body mass, having an allometric exponent of -0.28. The contribution of this n-3 polyunsaturate to the unsaturation index varied with body size, ranging from less than a 6%contribution in the emu to approximately 70% in the hummingbird. Such allometric variation in the acyl composition of bird muscle phospholipids is similar to that observed in mammals, although birds have fewer n-3 polyunsaturates and more n-6 polyunsaturates than do mammalian phospholipids. This allometric variation in phospholipid acyl composition is discussed with respect to both the metabolic intensity and lifespan of different sized bird species.
5
Briggs, Derek E. G., and Christopher Nedin. "The taphonomy and affinities of the problematic fossilMyoscolexfrom the Lower Cambrian Emu Bay Shale of South Australia." Journal of Paleontology 71, no. 1 (January 1997): 22–32. http://dx.doi.org/10.1017/s0022336000038919.
Full textAbstract:
Most of the specimens ofMyoscolex atelesGlaessner, 1979, the most abundant soft-bodied taxon in the Big Gully fauna from the Lower Cambrian Emu Bay Shale of South Australia, preserveonlythe phosphatized trunk muscles, in striking contrast to the organic residues that characterize other Burgess-Shale-type biotas. This is the oldest phosphatized muscle tissue and the first thus far reported from the Cambrian. The extent of phosphatization implies a source in addition to the animal itself, and this is reflected in high levels of phosphate in the Big Gully sequence compared to other shales. The apparent anomaly posed by the extensive preservation of labile muscle tissue as opposed to the more decay resistant cuticle is explained by the role of bacterial processes in the preservation of soft tissues. New specimens ofMyoscolexreveal a variable number of trunk somites with possible tergites, and flap-like appendages. There is evidence for at least three eyes on the head, and a proboscis may have been present. An annelid affinity is rejected andMyoscolexis reinterpreted as anOpabinia-likeanimal with possible affinities with the arachnomorph arthropods.
6
Kluis, Logan, Nathan Keller, Hedan Bai, Narahari Iyengar, Robert Shepherd, and Ana Diaz-Artiles. "Reducing Metabolic Cost During Planetary Ambulation Using Robotic Actuation." Aerospace Medicine and Human Performance 92, no. 7 (July 1, 2021): 570–78. http://dx.doi.org/10.3357/amhp.5754.2021.
Full textAbstract:
INTRODUCTION: Current spacesuits are cumbersome and metabolically expensive. The use of robotic actuators could improve extravehicular activity performance. We propose a novel method to quantify the benefit of robotic actuators during planetary ambulation.METHODS: Using the OpenSim framework, we completed a biomechanical analysis of three walking conditions: unsuited, suited with the extravehicular mobility unit (EMU) spacesuit (represented as external joint torques applied to human joints), and suited with the EMU and assisted by robotic actuators capable of producing up to 10 Nm of torque. For each scenario, we calculated the inverse kinematics and inverse dynamics of the lower body joints (hip, knee, and ankle). We also determined the activation of muscles and robotic actuators (when present). Finally, from inverse dynamics and muscle activation results, the metabolic cost of one gait cycle was calculated in all three conditions.RESULTS: The moments of lower body joints increased due to the increased resistance to movement from the spacesuit. The additional torque increased the overall metabolic cost by 85 compared to the unsuited condition. The assistive robotic actuators were able to reduce the metabolic cost induced by EMU resistance by 15.DISCUSSION: Our model indicates that the majority of metabolic cost reduction can be attributed to the actuators located at the hip. The robotic actuators reduced metabolic cost similar to that of modern-day actuators used to improve walking. During a Mars mission, the actuators could save one crewmember up to 100,000 kilocal on one 539-d planetary expedition.Kluis L, Keller N, Bai H, Iyengar N, Shepherd R, Diaz-Artiles A. Reducing metabolic cost during planetary ambulation using robotic actuation. Aerosp Med Hum Perform. 2021; 92(7):570578.
7
Bucław, Mateusz, Adam Lepczyński, Agnieszka Herosimczyk, Małgorzata Ożgo, Danuta Szczerbińska, Danuta Majewska, Kamila Liput, and Mariusz Pierzchała. "Post mortem changes in M. iliotibialis lateralis muscle protein profile of emu (Dromaius novaehollandiae)." Meat Science 180 (October 2021): 108562. http://dx.doi.org/10.1016/j.meatsci.2021.108562.
Full text
8
Ebersole, Kyle T., and David M. Malek. "Fatigue and the Electromechanical Efficiency of the Vastus Medialis and Vastus Lateralis Muscles." Journal of Athletic Training 43, no. 2 (March 1, 2008): 152–56. http://dx.doi.org/10.4085/1062-6050-43.2.152.
Full textAbstract:
Abstract Context: The relationship between the amplitudes of the mechanomyographic (MMG) and electromyographic (EMG) signals has been used to examine the “electromechanical efficiency” (EME) of normal and diseased muscle. The EME may help us to better understand the neuromuscular relationship between the vastus medialis and vastus lateralis muscles. Objective: To examine the EME of the vastus medialis and vastus lateralis muscles during a fatiguing task. Design: Repeated-measures design. Setting: Research laboratory. Patients or Other Participants: Ten healthy males (age = 23.2 ± 1.2 years) with no history of knee injury. Intervention(s): Seventy-five consecutive, maximal concentric isokinetic leg extensions at a velocity of 180°/s. Main Outcomes Measure(s): Bipolar surface EMG electrodes were placed over the vastus medialis and vastus lateralis muscles, with an MMG contact sensor placed adjacent to the superior EMG electrode on each muscle. The MMG and EMG amplitude values (root mean squares) were calculated for each of the 75 repetitions and normalized to the highest value from the 75 repetitions. The EME was expressed as the ratio of the log-transformed normalized MMG amplitude to the normalized EMG amplitude. For each muscle, the linear relationship for the normalized-group mean EME was determined across the 75 repetitions. Results: Linear regression indicated decreases in torque (R2 = .96), vastus medialis EME (R2 = .73), and vastus lateralis EME (R2 = .73). The slopes for the vastus medialis and vastus lateralis EME were not different (P > .10). Conclusions: The similarities in the fatigue-induced decreases in EME for the vastus medialis and vastus lateralis muscles suggested that symmetry was present between the muscles in the electric and mechanical responses to repeated, maximal muscle actions. The EME measurements may provide a unique insight into the influence of fatigue on the contractile properties of skeletal muscle, including alterations that occur to the intrinsic electric and mechanical components. The EME may be useful in assessing and quantifying clinically relevant asymmetries in vastus medialis and vastus lateralis muscle function in those with knee injuries.
9
Fitzgerald, D. R., L. D. Thompson, M. F. Miller, and L. C. Hoover. "Cooking Temperature, Bird Type, and Muscle Origin Effects on Sensory Properties of Broiled Emu Steaks." Journal of Food Science 64, no. 1 (January 1999): 167–70. http://dx.doi.org/10.1111/j.1365-2621.1999.tb09884.x.
Full text
10
Berge, P., J. Lepetit, M. Renerre, and C. Touraille. "Meat quality traits in the emu (Dromaius novaehollandiae) as affected by muscle type and animal age." Meat Science 45, no. 2 (February 1997): 209–21. http://dx.doi.org/10.1016/s0309-1740(96)00040-x.
Full text
11
Mukhtar Alam, Mohd, and Abid Ali Khan. "Electromyography-based Fatigue Assessment During Endurance Testing by Different Vibration Training Protocols." Iranian Rehabilitation Journal 19, no. 1 (March 1, 2021): 85–98. http://dx.doi.org/10.32598/irj.19.1.1150.1.
Full textAbstract:
Objectives: This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB)." This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB). Methods: A randomized comparative experimental design was used during endurance test with 8 VT protocols; based on different combinations of vibration frequency (35 & 45 Hz), amplitude (3±0.5g & 9±0.5g), and exposure duration (30 & 60 seconds), i.e., were given to the study participants for 4 days. A random sampling of participants was conducted from two groups (n=56/group), as follows: individuals with a Sedentary Lifestyle (SL) and a group of Construction Workers (CW). Results: Multivariate Analysis of Variance (MANOVA) results indicated a significant increase in EMG rms, median frequency, waveform length, mean absolute value (P<0.001), and the variance of EMG signal (P<0.05) (except in ECU for the SL group and ECRB for the CW group on the variance of EMG signal) after VT in all muscles of both research groups. Therefore, an increase in the EMG parameter value after a grip endurance task revealing an elevation in EMG signal amplitude is indicative of muscle fiber fatigue. Furthermore, the strongest correlation was found between grip endurance and WL (r=0.471, P<0.001), and EMG rms (r=0.401, P<0.001) of the ECU muscle in the SL group only. Discussion: The patterns of EMG signal represented the amplitude and spectral parameters of the signal, enabling real-time fatigue analysis. Additionally, surface EMG information is useful for indirectly evaluating performance fatigue during the endurance test.
12
Rosser, Benjamin W. C., and John C. George. "Histochemical Characterization and Distribution of Fiber Types in the Pectoralis Muscle of the Ostrich (Struthio camelus) and Emu (Dromaius novaehollandiae)." Acta Zoologica 66, no. 4 (December 1985): 191–98. http://dx.doi.org/10.1111/j.1463-6395.1985.tb00839.x.
Full text
13
Sommer, J. R., J. Junker, E. Bossen, I. Taylor, B. Scherer, and T. High. "Couplings, EJSR, Gap junctions, ECC, in Ratite Heart Conduction Fibers." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 3 (August 12, 1990): 190–91. http://dx.doi.org/10.1017/s0424820100158492.
Full textAbstract:
The ultrastructure of avian hearts has provided seminal information regarding striated muscle function. Extended junctional SR (EJSR) in avian hearts suggests that excitation-contraction coupling (ECC) is accomplished through a diffusible transmitter substance, but raises questions regarding the function of “couplings” in general. Other information gleaned from small avian hearts has elucidated adaptations of the individual and appositional geometry of the conduction fibers (CF) to functional demands imposed by different heart sizes and rates, as well as the relationship between the size of gap junctions (GJ), cell input resistance and coupling resistance between cells. The hearts of ratites (ostrich, emu, rhea) are very large (> 1 kg) and beat at about 50/min. Their working myocytes are almost identical to those found in chickens.We investigated the following questions: 1. Do ratite CF contain “couplings”, EJSR and corbular SR? 2. Are there differences in geometry between the CF of small, fast beating, and large, slow beating hearts as is the case in mammals?
14
Ni, Cheng-Hua, Yueh-Hsun Lu, Li-Wei Chou, Shu-Fen Kuo, Chia-Huei Lin, Shang-Lin Chiang, Liang-Hsuan Lu, Xin-Miao Wang, Jia-Lan Chang, and Chueh-Ho Lin. "Analysis of Vibration Frequency and Direction for Facilitating Upper-Limb Muscle Activity." Biology 12, no. 1 (December 27, 2022): 48. http://dx.doi.org/10.3390/biology12010048.
Full textAbstract:
We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively.
15
Zhang, Jian, Rahul Soangra, and Thurmon E. Lockhart. "A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance." Sci 2, no. 2 (June 3, 2020): 39. http://dx.doi.org/10.3390/sci2020039.
Full textAbstract:
One of the most basic pieces of information gained from dynamic electromyography is accurately defining muscle action and phase timing within the gait cycle. The human gait relies on selective timing and the intensity of appropriate muscle activations for stability, loading, and progression over the supporting foot during stance, and further to advance the limb in the swing phase. A common clinical practice is utilizing a low-pass filter to denoise integrated electromyogram (EMG) signals and to determine onset and cessation events using a predefined threshold. However, the accuracy of the defining period of significant muscle activations via EMG varies with the temporal shift involved in filtering the signals; thus, the low-pass filtering method with a fixed order and cut-off frequency will introduce a time delay depending on the frequency of the signal. In order to precisely identify muscle activation and to determine the onset and cessation times of the muscles, we have explored here onset and cessation epochs with denoised EMG signals using different filter banks: the wavelet method, empirical mode decomposition (EMD) method, and ensemble empirical mode decomposition (EEMD) method. In this study, gastrocnemius muscle onset and cessation were determined in sixteen participants within two different age groups and under two different walking conditions. Low-pass filtering of integrated EMG (iEMG) signals resulted in premature onset (28% stance duration) in younger and delayed onset (38% stance duration) in older participants, showing the time-delay problem involved in this filtering method. Comparatively, the wavelet denoising approach detected onset for normal walking events most precisely, whereas the EEMD method showed the smallest onset deviation. In addition, EEMD denoised signals could further detect pre-activation onsets during a fast walking condition. A comprehensive comparison is discussed on denoising EMG signals using EMD, EEMD, and wavelet denoising in order to accurately define an onset of muscle under different walking conditions.
16
Zhang, Jian, Rahul Soangra, and Thurmon E. Lockhart. "A Comparison of Denoising Methods in Onset Determination in Medial Gastrocnemius Muscle Activations during Stance." Sci 2, no. 3 (July 7, 2020): 53. http://dx.doi.org/10.3390/sci2030053.
Full textAbstract:
One of the most basic pieces of information gained from dynamic electromyography is accurately defining muscle action and phase timing within the gait cycle. The human gait relies on selective timing and the intensity of appropriate muscle activations for stability, loading, and progression over the supporting foot during stance, and further to advance the limb in the swing phase. A common clinical practice is utilizing a low-pass filter to denoise integrated electromyogram (EMG) signals and to determine onset and cessation events using a predefined threshold. However, the accuracy of the defining period of significant muscle activations via EMG varies with the temporal shift involved in filtering the signals; thus, the low-pass filtering method with a fixed order and cut-off frequency will introduce a time delay depending on the frequency of the signal. In order to precisely identify muscle activation and to determine the onset and cessation times of the muscles, we have explored here onset and cessation epochs with denoised EMG signals using different filter banks: the wavelet method, empirical mode decomposition (EMD) method, and ensemble empirical mode decomposition (EEMD) method. In this study, gastrocnemius muscle onset and cessation were determined in sixteen participants within two different age groups and under two different walking conditions. Low-pass filtering of integrated EMG (iEMG) signals resulted in premature onset (28% stance duration) in younger and delayed onset (38% stance duration) in older participants, showing the time-delay problem involved in this filtering method. Comparatively, the wavelet denoising approach detected onset for normal walking events most precisely, whereas the EEMD method showed the smallest onset deviation. In addition, EEMD denoised signals could further detect pre-activation onsets during a fast walking condition. A comprehensive comparison is discussed on denoising EMG signals using EMD, EEMD, and wavelet denoising in order to accurately define an onset of muscle under different walking conditions.
17
De Luca, Carlo J., and Zeynep Erim. "Common Drive in Motor Units of a Synergistic Muscle Pair." Journal of Neurophysiology 87, no. 4 (April 1, 2002): 2200–2204. http://dx.doi.org/10.1152/jn.00793.2001.
Full textAbstract:
The interaction among the motor units of the extensor carpi radialis longus (ECRL) and the extensor carpi ulnaris (ECU) muscles in man was studied during wrist extensions in which the two muscles acted as synergists. Intramuscular recordings were obtained using special quadrifilar needle electrodes. Isometric wrist extensions at 20–30% of the maximal effort were studied. The electromyographic (EMG) signals were decomposed into the individual motor-unit action potential trains comprising the signal. The interaction among motor units were characterized by the estimated time-varying mean firing rate and the cross-correlation between the time-varying mean firing rates of pairs of motor units. Pairs of motor units within each muscle as well as pairs of motor units across the muscles were considered. In-phase common fluctuations, termed common drive, were observed in the mean firing rates of motor units within each muscle, consistent with earlier work on other muscles. Common fluctuations were also observed between the firing rates of ECU and ECRL motor units albeit with a variable phase shift. The existence of common drive across synergistic muscles was interpreted as implying that the CNS considers the muscles as a functional unit when they act as synergists.
18
Bennie, Kirsty J., Vincent M. Ciriello, Peter W. Johnson, and Jack Tigh Dennerlein. "EMG Changes of the ECU Muscle with Exposure to Repetitive Ulnar Deviation." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 46, no. 13 (September 2002): 1086–89. http://dx.doi.org/10.1177/154193120204601317.
Full textAbstract:
Our objective was to quantify changes in muscle EMG activity due to repetitive work. Using a repeated measures design, 13 females participated in 3 conditions, each lasting two eight-hour days: a control inactive condition, and two repetitive work conditions with ulnar deviation tasks at 20 and 25 repetitions per minute. EMG of the extensor carpi ulnaris muscle (ECU) was recorded during voluntary isometric contractions (20% and 60% MVC) eight times throughout the work and control days. The amplitude of the EMG signal was lower on workdays compared to the control days. Initial median frequency of the EMG signal showed no change between the control and workdays; however, the decline of the median frequency with respect to time over the course of each isometric contraction was steeper during workdays compared to control days. These changes suggest that the muscles are in an early stage of fatigue when working for an eight-hour workday.
19
Mitchell, Cameron, Rotem Cohen, Raffy Dotan, David Gabriel, Panagiota Klentrou, and Bareket Falk. "Rate of Muscle Activation in Power-and Endurance-Trained Boys." International Journal of Sports Physiology and Performance 6, no. 1 (March 2011): 94–105. http://dx.doi.org/10.1123/ijspp.6.1.94.
Full textAbstract:
Previous studies in adults have demonstrated power athletes as having greater muscle force and muscle activation than nonathletes. Findings on endurance athletes are scarce and inconsistent. No comparable data on child athletes exist.Purpose:This study compared peak torque (Tq), peak rate of torque development (RTD), and rate of muscle activation (EMG rise, Q30), in isometric knee extension (KE) and fexion (KF), in pre- and early-pubertal power- and endurance-trained boys vs minimally active nonathletes.Methods:Nine gymnasts, 12 swimmers, and 18 nonathletes (7–12 y), performed fast, maximal isometric KE and KF. Values for Tq, RTD, electromechanical delay (EMD), and Q30 were calculated from averaged torque and surface EMG traces.Results:No group differences were observed in Tq, normalized for muscle cross-sectional area. The Tq-normalized KE RTD was highest in power athletes (6.2 ± 1.9, 4.7 ± 1.2, 5.0 ± 1.5 N·m·s–1, for power, endurance, and nonathletes, respectively), whereas no group differences were observed for KF. The KE Q30 was significantly greater in power athletes, both in absolute terms and relative to peak EMG amplitude (9.8 ± 7.0, 5.9 ± 4.2, 4.4 ± 2.2 mV·ms and 1.7 ± 0.8, 1.1 ± 0.6, 0.9 ± 0.5 (mV·ms)/(mV) for power, endurance, and nonathletes, respectively), with no group differences in KF. The KE EMD tended to be shorter (P = .07) in power athletes during KE (71.0 ± 24.1, 87.8 ± 18.0, 88.4 ± 27.8 ms, for power, endurance, and nonathletes), with no group differences in KF.Conclusions:Pre- and early-pubertal power athletes have enhanced rate of muscle activation in specifically trained muscles compared with controls or endurance athletes, suggesting that specific training can result in muscle activation-pattern changes before the onset of puberty.
20
Soangra, Rahul, R. Sivakumar, E. R. Anirudh, Sai Viswanth Reddy Y., and Emmanuel B. John. "Evaluation of surgical skill using machine learning with optimal wearable sensor locations." PLOS ONE 17, no. 6 (June 3, 2022): e0267936. http://dx.doi.org/10.1371/journal.pone.0267936.
Full textAbstract:
Evaluation of surgical skills during minimally invasive surgeries is needed when recruiting new surgeons. Although surgeons’ differentiation by skill level is highly complex, performance in specific clinical tasks such as pegboard transfer and knot tying could be determined using wearable EMG and accelerometer sensors. A wireless wearable platform has made it feasible to collect movement and muscle activation signals for quick skill evaluation during surgical tasks. However, it is challenging since the placement of multiple wireless wearable sensors may interfere with their performance in the assessment. This study utilizes machine learning techniques to identify optimal muscles and features critical for accurate skill evaluation. This study enrolled a total of twenty-six surgeons of different skill levels: novice (n = 11), intermediaries (n = 12), and experts (n = 3). Twelve wireless wearable sensors consisting of surface EMGs and accelerometers were placed bilaterally on bicep brachii, tricep brachii, anterior deltoid, flexor carpi ulnaris (FCU), extensor carpi ulnaris (ECU), and thenar eminence (TE) muscles to assess muscle activations and movement variability profiles. We found features related to movement complexity such as approximate entropy, sample entropy, and multiscale entropy played a critical role in skill level identification. We found that skill level was classified with highest accuracy by i) ECU for Random Forest Classifier (RFC), ii) deltoid for Support Vector Machines (SVM) and iii) biceps for Naïve Bayes Classifier with classification accuracies 61%, 57% and 47%. We found RFC classifier performed best with highest classification accuracy when muscles are combined i) ECU and deltoid (58%), ii) ECU and biceps (53%), and iii) ECU, biceps and deltoid (52%). Our findings suggest that quick surgical skill evaluation is possible using wearables sensors, and features from ECU, deltoid, and biceps muscles contribute an important role in surgical skill evaluation.
21
Hochreiter, Jakob, Eric Hoche, Luisa Janik, Gerd Fabian Volk, Lutz Leistritz, Christoph Anders, and Orlando Guntinas-Lichius. "Machine-Learning-Based Detecting of Eyelid Closure and Smiling Using Surface Electromyography of Auricular Muscles in Patients with Postparalytic Facial Synkinesis: A Feasibility Study." Diagnostics 13, no. 3 (February 2, 2023): 554. http://dx.doi.org/10.3390/diagnostics13030554.
Full textAbstract:
Surface electromyography (EMG) allows reliable detection of muscle activity in all nine intrinsic and extrinsic ear muscles during facial muscle movements. The ear muscles are affected by synkinetic EMG activity in patients with postparalytic facial synkinesis (PFS). The aim of the present work was to establish a machine-learning-based algorithm to detect eyelid closure and smiling in patients with PFS by recording sEMG using surface electromyography of the auricular muscles. Sixteen patients (10 female, 6 male) with PFS were included. EMG acquisition of the anterior auricular muscle, superior auricular muscle, posterior auricular muscle, tragicus muscle, orbicularis oculi muscle, and orbicularis oris muscle was performed on both sides of the face during standardized eye closure and smiling tasks. Machine-learning EMG classification with a support vector machine allowed for the reliable detection of eye closure or smiling from the ear muscle recordings with clear distinction to other mimic expressions. These results show that the EMG of the auricular muscles in patients with PFS may contain enough information to detect facial expressions to trigger a future implant in a closed-loop system for electrostimulation to improve insufficient eye closure and smiling in patients with PFS.
22
Safie, Sairul Izwan, and Rosuhana Rahim. "Quality assessment on muscle locations for speech representation." Indonesian Journal of Electrical Engineering and Computer Science 17, no. 2 (February 1, 2020): 957. http://dx.doi.org/10.11591/ijeecs.v17.i2.pp957-967.
Full textAbstract:
<span lang="EN-US">There are more than 68 muscles, which are activated either simultaneously or sequentially during speech production. To monitor the signals from all these muscles at once, involve a lot of sensors and such system is very expensive. In the Quran therapeutic treatment applications, the use of specific muscles is very important, for the production of correct Arabic pronunciation. The proper pronunciation will improve the reader's understanding of what is being read, thus assisting the effectiveness of the therapy process. The objective of this study is to identify the most optimal muscle location, which is suitable for monitoring the quality of a recitation during the Quran’s therapeutic process, based on the information content embedded in their Electromyogram (EMG) signals. Empirical Mode Decomposition (EMD) technique was used in this study to extract features of the EMG while the combination of Hilbert Huang Spectral Entropy (HHSE) and Kullback Leibler Divergence (KLD) techniques were used to quantify the information content in each feature. Combination of these techniques managed to rank ten widely used speech muscles in the literature based upon their information content. Four muscle locations have been suggested, which is believed to be sufficient in developing a low-cost self-assessment system for monitoring Quran recitation.</span>
23
Poston, Brach, Alessander Danna-Dos Santos, Mark Jesunathadas, Thomas M. Hamm, and Marco Santello. "Force-Independent Distribution of Correlated Neural Inputs to Hand Muscles During Three-Digit Grasping." Journal of Neurophysiology 104, no. 2 (August 2010): 1141–54. http://dx.doi.org/10.1152/jn.00185.2010.
Full textAbstract:
The ability to modulate digit forces during grasping relies on the coordination of multiple hand muscles. Because many muscles innervate each digit, the CNS can potentially choose from a large number of muscle coordination patterns to generate a given digit force. Studies of single-digit force production tasks have revealed that the electromyographic (EMG) activity scales uniformly across all muscles as a function of digit force. However, the extent to which this finding applies to the coordination of forces across multiple digits is unknown. We addressed this question by asking subjects ( n = 8) to exert isometric forces using a three-digit grip (thumb, index, and middle fingers) that allowed for the quantification of hand muscle coordination within and across digits as a function of grasp force (5, 20, 40, 60, and 80% maximal voluntary force). We recorded EMG from 12 muscles (6 extrinsic and 6 intrinsic) of the three digits. Hand muscle coordination patterns were quantified in the amplitude and frequency domains (EMG–EMG coherence). EMG amplitude scaled uniformly across all hand muscles as a function of grasp force (muscle × force interaction: P = 0.997; cosines of angle between muscle activation pattern vector pairs: 0.897–0.997). Similarly, EMG–EMG coherence was not significantly affected by force ( P = 0.324). However, coherence was stronger across extrinsic than that across intrinsic muscle pairs ( P = 0.0039). These findings indicate that the distribution of neural drive to multiple hand muscles is force independent and may reflect the anatomical properties or functional roles of hand muscle groups.
24
Danna-Dos Santos, Alessander, Brach Poston, Mark Jesunathadas, Lisa R. Bobich, Thomas M. Hamm, and Marco Santello. "Influence of Fatigue on Hand Muscle Coordination and EMG-EMG Coherence During Three-Digit Grasping." Journal of Neurophysiology 104, no. 6 (December 2010): 3576–87. http://dx.doi.org/10.1152/jn.00583.2010.
Full textAbstract:
Fingertip force control requires fine coordination of multiple hand muscles within and across the digits. While the modulation of neural drive to hand muscles as a function of force has been extensively studied, much less is known about the effects of fatigue on the coordination of simultaneously active hand muscles. We asked eight subjects to perform a fatiguing contraction by gripping a manipulandum with thumb, index, and middle fingers while matching an isometric target force (40% maximal voluntary force) for as long as possible. The coordination of 12 hand muscles was quantified as electromyographic (EMG) muscle activation pattern (MAP) vector and EMG-EMG coherence. We hypothesized that muscle fatigue would cause uniform changes in EMG amplitude across all muscles and an increase in EMG-EMG coherence in the higher frequency bands but with an invariant heterogeneous distribution across muscles. Muscle fatigue caused a 12.5% drop in the maximum voluntary contraction force ( P < 0.05) at task failure and an increase in the SD of force ( P < 0.01). Although EMG amplitude of all muscles increased during the fatiguing contraction ( P < 0.001), the MAP vector orientation did not change, indicating that a similar muscle coordination pattern was used throughout the fatiguing contraction. Last, EMG-EMG coherence (0–35 Hz) was significantly greater at the end than at the beginning of the fatiguing contraction ( P < 0.01) but was heterogeneously distributed across hand muscles. These findings suggest that similar mechanisms are involved for modulating and sustaining digit forces in nonfatiguing and fatiguing contractions, respectively.
25
Schumann, Nikolaus P., Kevin Bongers, Hans C. Scholle, and Orlando Guntinas-Lichius. "Atlas of voluntary facial muscle activation: Visualization of surface electromyographic activities of facial muscles during mimic exercises." PLOS ONE 16, no. 7 (July 19, 2021): e0254932. http://dx.doi.org/10.1371/journal.pone.0254932.
Full textAbstract:
Complex facial muscle movements are essential for many motoric and emotional functions. Facial muscles are unique in the musculoskeletal system as they are interwoven, so that the contraction of one muscle influences the contractility characteristic of other mimic muscles. The facial muscles act more as a whole than as single facial muscle movements. The standard for clinical and psychosocial experiments to detect these complex interactions is surface electromyography (sEMG). What is missing, is an atlas showing which facial muscles are activated during specific tasks. Based on high-resolution sEMG data of 10 facial muscles of both sides of the face simultaneously recorded during 29 different facial muscle tasks, an atlas visualizing voluntary facial muscle activation was developed. For each task, the mean normalized EMG amplitudes of the examined facial muscles were visualized by colors. The colors were spread between the lowest and highest EMG activity. Gray shades represent no to very low EMG activities, light and dark brown shades represent low to medium EMG activities and red shades represent high to very high EMG activities relatively with respect to each task. The present atlas should become a helpful tool to design sEMG experiments not only for clinical trials and psychological experiments, but also for speech therapy and orofacial rehabilitation studies.
26
Tahan, Nahid, Amir Massoud Arab, Bita Vaseghi, and Khosro Khademi. "Electromyographic Evaluation of Abdominal-Muscle Function With and Without Concomitant Pelvic-Floor-Muscle Contraction." Journal of Sport Rehabilitation 22, no. 2 (May 2013): 108–14. http://dx.doi.org/10.1123/jsr.22.2.108.
Full textAbstract:
Context:Coactivation of abdominal and pelvic-floor muscles (PFM) is an issue considered by researchers recently. Electromyography (EMG) studies have shown that the abdominal-muscle activity is a normal response to PFM activity, and increase in EMG activity of the PFM concomitant with abdominal-muscle contraction was also reported.Objective:The purpose of this study was to compare the changes in EMG activity of the deep abdominal muscles during abdominal-muscle contraction (abdominal hollowing and bracing) with and without concomitant PFM contraction in healthy and low-back-pain (LBP) subjects.Design:A 2 × 2 repeated-measures design.Setting:Laboratory.Participants:30 subjects (15 with LBP, 15 without LBP).Main Outcome Measures:Peak rectified EMG of abdominal muscles.Results:No difference in EMG of abdominal muscles with and without concomitant PFM contraction in abdominal hollowing (P = .84) and abdominal bracing (P = .53). No difference in EMG signal of abdominal muscles with and without PFM contraction between LBP and healthy subjects in both abdominal hollowing (P = .88) and abdominal bracing (P = .98) maneuvers.Conclusion:Adding PFM contraction had no significant effect on abdominal-muscle contraction in subjects with and without LBP.
27
Griffin, D. M., H. M. Hudson, A. Belhaj-Saïf, B. J. McKiernan, and P. D. Cheney. "Do Corticomotoneuronal Cells Predict Target Muscle EMG Activity?" Journal of Neurophysiology 99, no. 3 (March 2008): 1169–986. http://dx.doi.org/10.1152/jn.00906.2007.
Full textAbstract:
Data from two rhesus macaques were used to investigate the pattern of cortical cell activation during reach-to-grasp movements in relation to the corresponding activation pattern of the cell's facilitated target muscles. The presence of postspike facilitation (PSpF) in spike-triggered averages (SpTAs) of electromyographic (EMG) activity was used to identify cortical neurons with excitatory synaptic linkages with motoneurons. EMG activity from 22 to 24 muscles of the forelimb was recorded together with the activity of M1 cortical neurons. The extent of covariation was characterized by 1) identifying the task segment containing the cell and target muscle activity peaks, 2) quantifying the timing and overlap between corticomotoneuronal (CM) cell and EMG peaks, and 3) applying Pearson correlation analysis to plots of CM cell firing rate versus EMG activity of the cell's facilitated muscles. At least one firing rate peak, for nearly all (95%) CM cells tested, matched a corresponding peak in the EMG activity of the cell's target muscles. Although some individual CM cells had very strong correlations with target muscles, overall, substantial disparities were common. We also investigated correlations for ensembles of CM cells sharing the same target muscle. The ensemble population activity of even a small number of CM cells influencing the same target muscle produced a relatively good match ( r ≥ 0.8) to target muscle EMG activity. Our results provide evidence in support of the notion that corticomotoneuronal output from primary motor cortex encodes movement in a framework of muscle-based parameters, specifically muscle-activation patterns as reflected in EMG activity.
28
Geenen, C., E. Consky, and P. Ashby. "Localizing Muscles for Botulinum Toxin Treatment of Focal Hand Dystonia." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 23, no. 3 (August 1996): 194–97. http://dx.doi.org/10.1017/s0317167100038506.
Full textAbstract:
AbstractBackground: There is currently no consensus on the best way to localize muscles in the forearm for botulinum toxin (BTX) injection. We devised a study to compare electromyography (EMG) with local stimulation through a cannula for localizing forearm muscles for botulinum toxin (BTX) injection, and for predicting the risk of unwanted weakness in non-target muscles. Methods: In 12 patients with focal hand dystonia a single “target” muscle, determined by clinical examination to contribute most to the dystonic hand posture, was selected for botulinum toxin injection. The patients were randomized into 2 treatment groups, one in which the target muscle was localized by recording the EMG signals during voluntary contractions (8 patients) and the other in which the target muscle was localized by local electrical stimulation (4 patients). The target muscle was then injected with a standardized dose of BTX. Results: At follow-up 3 weeks after BTX injection the target muscle was weakened in 7/12 patients (4/8 of the EMG group, and 3/4 of the stimulation group). Additional non-injected muscles, adjacent to the target muscle, were weakened in 5 of these 7 patients, presumably from diffusion of the toxin. Conclusions: Localization by stimulation is probably at least as good as EMG. Each technique has certain advantages. Weakness of “non-target” muscles was not consistently predicted by either EMG or stimulation suggesting that BTX diffuses farther than the volume conduction of EMG signals or the spread of effective stimulus current.
29
Watanabe, Kohei, and Shideh Narouei. "Association between Oxygen Consumption and Surface Electromyographic Amplitude and Its Variation within Individual Calf Muscles during Walking at Various Speeds." Sensors 21, no. 5 (March 3, 2021): 1748. http://dx.doi.org/10.3390/s21051748.
Full textAbstract:
Surface electromyography (EMG) has been used to estimate muscle work and physiological burden of the whole body during human movements. However, there are spatial variations in surface EMG responses within individual muscles. The aim of this study was to investigate the relation between oxygen consumption and surface EMG responses of lower leg muscles during walking at various speeds and to quantify its spatial variation within an individual muscle. Nine young males walked on a treadmill at four speeds: preferred minus 1 km/h, preferred, preferred plus 1 km/h, and preferred plus 2 km/h, and the metabolic response was measured based on the expired gas. High-density surface EMG of the tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius, and soleus muscles was performed using 64 two-dimensional electrode grids. Correlation coefficients between oxygen consumption and the surface EMG amplitude were calculated across the gait speeds for each channel in the electrode grid and for individual muscles. Mean correlation coefficients across electrodes were 0.69–0.87 for the four individual muscles, and the spatial variation of correlation between the surface EMG amplitude and oxygen consumption within an electrode grid was significantly greater in MG muscle than in TA muscle (Quartile deviations: 0.24 for MG and 0.02 for TA, p < 0.05). These results suggest that the physiological burden of the whole body during gait at various speeds can be estimated from the surface EMG amplitude of calf muscles, but we need to note its spatial distribution within the MG muscle.
30
Alam, Mohd Mukhtar, Abid Ali Khan, and Mohd Farooq. "Effects of vibratory massage therapy on grip strength, endurance time and forearm muscle performance." Work 68, no. 3 (March 26, 2021): 619–32. http://dx.doi.org/10.3233/wor-203397.
Full textAbstract:
BACKGROUND: Vibration therapy (VT) causes an increase in motor unit activation tendency, an involuntary recruitment of earlier sedentary motor units, which increases the muscle fiber force generating capacity and muscle performance. OBJECTIVE: To evaluate the effect of vibratory massage therapy at 23 Hz and 35 Hz on grip strength, endurance, and forearm muscle performance (in terms of EMG activity). METHODS: Ten healthy and right-handed men participated voluntarily in this study. The experiment was characterized by the measurement of MVC (maximal voluntary contraction) grip strength and grip endurance time at 50%MVC, accompanied by the corresponding measurement of the EMG signals of the muscles viz., flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi radialis brevis (ECRB); and extensor carpi ulnaris (ECU) in supine posture. RESULTS: MANCOVA results showed significant effects of VT frequency on endurance time (p < 0.001); but no significant effect on the grip strength (p = 0.161) and muscle performance (in terms of EMG activities of the forearm muscles). However, VT improves the MVC grip strength and grip endurance time (better at 35 Hz). The Pearson correlation was significant between: weight, palm length, palm circumference, and forearm length with MVC grip strength; and the palm length with the endurance time. In addition, the palm length, palm circumference, and forearm circumference generally serve to better predict MVC grip strength and grip endurance time. CONCLUSIONS: Vibration therapy at 35 Hz for 10 minutes on the forearms had a significant positive effect on the neuromuscular performance to enhance muscle performance of upper extermitites and can be used as the optimal range to study the effect of VT. Findings may be used to prepare guidelines for VT in rehabilitation, healthcare, sports, and medical for therapists.
31
Ranganathan, Rajiv, and Chandramouli Krishnan. "Extracting synergies in gait: using EMG variability to evaluate control strategies." Journal of Neurophysiology 108, no. 5 (September 1, 2012): 1537–44. http://dx.doi.org/10.1152/jn.01112.2011.
Full textAbstract:
There has been extensive debate as to whether muscle synergies in motor tasks reflect underlying neural organization or simply correlations in muscle activity that are imposed by the task. One possible means of distinguishing these two alternatives is through the analysis of variability in the electromyogram (EMG). Here, we simulated EMG in eight lower-limb muscles and introduced hypothetical neural coupling between specific muscle groups. Neural coupling was simulated by introducing correlations in the neural activation commands to different muscles (positive, negative, or zero coupling). When the entire EMG signal was used for analysis, the extracted synergies reflected only simultaneous muscle activity, regardless of the neural coupling between the muscles. On the other hand, examining the variability in the EMG after subtracting the ensemble average was successful in identifying the simulated neural coupling. The extracted synergies from these two methods were also different when we analyzed data from participants during treadmill walking. The results emphasize the importance of examining EMG variability to understand the neural basis of muscle synergies.
32
Assila, Najoua, Claudio Pizzolato, Romain Martinez, David G. Lloyd, and Mickaël Begon. "EMG-Assisted Algorithm to Account for Shoulder Muscles Co-Contraction in Overhead Manual Handling." Applied Sciences 10, no. 10 (May 20, 2020): 3522. http://dx.doi.org/10.3390/app10103522.
Full textAbstract:
Glenohumeral stability is essential for a healthy function of the shoulder. It is ensured partly by the scapulohumeral muscular balance. Accordingly, modelling muscle interactions is a key factor in the understanding of occupational pathologies, and the development of ergonomic interventions. While static optimization is commonly used to estimate muscle activations, it tends to underestimate the role of shoulder’s antagonist muscles. The purpose of this study was to implement experimental electromyographic (EMG) data to predict muscle activations that could account for the stabilizing role of the shoulder muscles. Kinematics and EMG were recorded from 36 participants while lifting a box from hip to eye level. Muscle activations and glenohumeral joint reactions were estimated using an EMG-assisted algorithm and compared to those obtained using static optimization with a generic and calibrated model. Muscle activations predicted with the EMG-assisted method were generally larger. Additionally, more interactions between the different rotator cuff muscles, as well as between primer actuators and stabilizers, were predicted with the EMG-assisted method. Finally, glenohumeral forces calculated from a calibrated model remained within the boundaries of the glenoid stability cone. These findings suggest that EMG-assisted methods could account for scapulohumeral muscle co-contraction, and thus their contribution to the glenohumeral stability.
33
Rüschenschmidt, Hanna, Gerd Fabian Volk, Christoph Anders, and Orlando Guntinas-Lichius. "Electromyography of Extrinsic and Intrinsic Ear Muscles in Healthy Probands and Patients with Unilateral Postparalytic Facial Synkinesis." Diagnostics 12, no. 1 (January 5, 2022): 121. http://dx.doi.org/10.3390/diagnostics12010121.
Full textAbstract:
There are currently no data on the electromyography (EMG) of all intrinsic and extrinsic ear muscles. The aim of this work was to develop a standardized protocol for a reliable surface EMG examination of all nine ear muscles in twelve healthy participants. The protocol was then applied in seven patients with unilateral postparalytic facial synkinesis. Based on anatomic preparations of all ear muscles on two cadavers, hot spots for the needle EMG of each individual muscle were defined. Needle and surface EMG were performed in one healthy participant; facial movements could be defined for the reliable activation of individual ear muscles’ surface EMG. In healthy participants, most tasks led to the activation of several ear muscles without any side difference. The greatest EMG activity was seen when smiling. Ipsilateral and contralateral gaze were the only movements resulting in very distinct activation of the transversus auriculae and obliquus auriculae muscles. In patients with facial synkinesis, ear muscles’ EMG activation was stronger on the postparalytic compared to the contralateral side for most tasks. Additionally, synkinetic activation was verifiable in the ear muscles. The surface EMG of all ear muscles is reliably feasible during distinct facial tasks, and ear muscle EMG enriches facial electrodiagnostics.
34
Attard, Marie R. G., Laura A. B. Wilson, Trevor H. Worthy, Paul Scofield, Peter Johnston, William C. H. Parr, and Stephen Wroe. "Moa diet fits the bill: virtual reconstruction incorporating mummified remains and prediction of biomechanical performance in avian giants." Proceedings of the Royal Society B: Biological Sciences 283, no. 1822 (January 13, 2016): 20152043. http://dx.doi.org/10.1098/rspb.2015.2043.
Full textAbstract:
The moa (Dinornithiformes) are large to gigantic extinct terrestrial birds of New Zealand. Knowledge about niche partitioning, feeding mode and preference among moa species is limited, hampering palaeoecological reconstruction and evaluation of the impacts of their extinction on remnant native biota, or the viability of exotic species as proposed ecological ‘surrogates'. Here we apply three-dimensional finite-element analysis to compare the biomechanical performance of skulls from five of the six moa genera, and two extant ratites, to predict the range of moa feeding behaviours relative to each other and to living relatives. Mechanical performance during biting was compared using simulations of the birds clipping twigs based on muscle reconstruction of mummified moa remains. Other simulated food acquisition strategies included lateral shaking, pullback and dorsoventral movement of the skull. We found evidence for limited overlap in biomechanical performance between the extant emu ( Dromaius novaehollandiae ) and extinct upland moa ( Megalapteryx didinus ) based on similarities in mandibular stress distribution in two loading cases, but overall our findings suggest that moa species exploited their habitats in different ways, relative to both each other and extant ratites. The broad range of feeding strategies used by moa, as inferred from interspecific differences in biomechanical performance of the skull, provides insight into mechanisms that facilitated high diversities of these avian herbivores in prehistoric New Zealand.
35
Elsais, Walaa M., Stephen J. Preece, Richard K. Jones, and Lee Herrington. "Could Relative Movement Between the Adductor Muscles and the Skin Invalidate Surface Electromyography Measurement?" Journal of Applied Biomechanics 36, no. 5 (October 1, 2020): 319–25. http://dx.doi.org/10.1123/jab.2019-0299.
Full textAbstract:
The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque–EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion–extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derive meaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors.
36
Cè, Emiliano, Susanna Rampichini, Eloisa Limonta, and Fabio Esposito. "Reliability of the Electromechanical Delay Components Assessment during the Relaxation Phase." Physiology Journal 2013 (March 6, 2013): 1–7. http://dx.doi.org/10.1155/2013/517838.
Full textAbstract:
The study aimed to assess by an electromyographic (EMG), mechanomyographic (MMG), and force-combined approach the electrochemical and mechanical components of the overall electromechanical delay during relaxation (R-EMD). Reliability of the measurements was also assessed. To this purpose, supramaximal tetanic stimulations (50 Hz) were delivered to the gastrocnemius medialis muscle of 17 participants. During stimulations, the EMG, MMG, and force signals were detected, and the time lag between EMG cessation and the beginning of force decay (Δt EMG-F, as temporal indicators of the electrochemical events) and from the initial force decrease to the largest negative peak of MMG signal during relaxation (Δt F-MMG, as temporal indicators of the mechanical events) was calculated, together with overall R-EMD duration (from EMG cessation to the largest MMG negative peak during relaxation). Peak force (pF), half relaxation time (HRT), and MMG peak-to-peak during the relaxation phase (R-MMG p-p) were also calculated. Test-retest reliability was assessed by Intraclass Correlation Coefficient (ICC). With a total R-EMD duration of 96.9 ± 1.9 ms, Δt EMG-F contributed for about 24% (23.4 ± 2.7 ms) while Δt F-MMG for about 76% (73.5 ± 3.2 ms). Reliability of the measurements was high for all variables. Our findings show that the main contributor to R-EMD is represented by the mechanical components (series elastic components and muscle fibres behaviour), with a high reliability level for this type of approach.
37
Aratow, M., R. E. Ballard, A. G. Crenshaw, J. Styf, D. E. Watenpaugh, N. J. Kahan, and A. R. Hargens. "Intramuscular pressure and electromyography as indexes of force during isokinetic exercise." Journal of Applied Physiology 74, no. 6 (June 1, 1993): 2634–40. http://dx.doi.org/10.1152/jappl.1993.74.6.2634.
Full textAbstract:
A direct method for measuring force production of specific muscles during dynamic exercise is presently unavailable. Previous studies indicate that both intramuscular pressure (IMP) and electromyography (EMG) correlate linearly with muscle contraction force during isometric exercise. The objective of this study was to compare IMP and EMG as linear assessors of muscle contraction force during dynamic exercise. IMP and surface EMG activity were recorded during concentric and eccentric isokinetic plantarflexion and dorsiflexion of the ankle joint from the tibialis anterior (TA) and soleus (SOL) muscles of nine male volunteers (28–54 yr). Ankle torque was measured using a dynamometer, and IMP was measured via catheterization. IMP exhibited better linear correlation than EMG with ankle joint torque during concentric contractions of the SOL (IMP R2 = 0.97, EMG R2 = 0.81) and the TA (IMP R2 = 0.97, EMG R2 = 0.90), as well as during eccentric contractions (SOL: IMP R2 = 0.91, EMG R2 = 0.51; TA: IMP R2 = 0.94, EMG R2 = 0.73). IMP provides a better index of muscle contraction force than EMG during concentric and eccentric exercise through the entire range of torque. IMP reflects intrinsic mechanical properties of individual muscles, such as length-tension relationships, which EMG is unable to assess.
38
Henry, Sharon M., Joyce Fung, and Fay B. Horak. "EMG Responses to Maintain Stance During Multidirectional Surface Translations." Journal of Neurophysiology 80, no. 4 (October 1, 1998): 1939–50. http://dx.doi.org/10.1152/jn.1998.80.4.1939.
Full textAbstract:
Henry, Sharon M., Joyce Fung, and Fay B. Horak. EMG responses to maintain stance during multidirectional surface translations. J. Neurophysiol. 80: 1939–1950, 1998. To characterize muscle synergy organization underlying multidirectional control of stance posture, electromyographic activity was recorded from 11 lower limb and trunk muscles of 7 healthy subjects while they were subjected to horizontal surface translations in 12 different, randomly presented directions. The latency and amplitude of muscle responses were quantified for each perturbation direction. Tuning curves for each muscle were examined to relate the amplitude of the muscle response to the direction of surface translation. The latencies of responses for the shank and thigh muscles were constant, regardless of perturbation direction. In contrast, the latencies for another thigh [tensor fascia latae (TFL)] and two trunk muscles [rectus abdominis (RAB) and erector spinae (ESP)] were either early or late, depending on the perturbation direction. These three muscles with direction-specific latencies may play different roles in postural control as prime movers or as stabilizers for different translation directions, depending on the timing of recruitment. Most muscle tuning curves were within one quadrant, having one direction of maximal activity, generally in response to diagonal surface translations. Two trunk muscles (RAB and ESP) and two lower limb muscles (semimembranosus and peroneus longus) had bipolar tuning curves, with two different directions of maximal activity, suggesting that these muscle can play different roles as part of different synergies, depending on translation direction. Muscle tuning curves tended to group into one of three regions in response to 12 different directions of perturbations. Two muscles [rectus femoris (RFM) and TFL] were maximally active in response to lateral surface translations. The remaining muscles clustered into one of two diagonal regions. The diagonal regions corresponded to the two primary directions of active horizontal force vector responses. Two muscles (RFM and adductor longus) were maximally active orthogonal to their predicted direction of maximal activity based on anatomic orientation. Some of the muscles in each of the synergic regions were not anatomic synergists, suggesting a complex central organization for recruitment of muscles. The results suggest that neither a simple reflex mechanism nor a fixed muscle synergy organization is adequate to explain the muscle activation patterns observed in this postural control task. Our results are consistent with a centrally mediated pattern of muscle latencies combined with peripheral influence on muscle magnitude. We suggest that a flexible continuum of muscle synergies that are modifiable in a task-dependent manner be used for equilibrium control in stance.
39
Osu, Rieko, and Hiroaki Gomi. "Multijoint Muscle Regulation Mechanisms Examined by Measured Human Arm Stiffness and EMG Signals." Journal of Neurophysiology 81, no. 4 (April 1, 1999): 1458–68. http://dx.doi.org/10.1152/jn.1999.81.4.1458.
Full textAbstract:
Multijoint muscle regulation mechanisms examined by measured human arm stiffness and EMG signals. Stiffness properties of the musculo-skeletal system can be controlled by regulating muscle activation and neural feedback gain. To understand the regulation of multijoint stiffness, we examined the relationship between human arm joint stiffness and muscle activation during static force control in the horizontal plane by means of surface electromyographic (EMG) studies. Subjects were asked to produce a specified force in a specified direction without cocontraction or they were asked to keep different cocontractions while producing or not producing an external force. The stiffness components of shoulder, elbow, and their cross-term and the EMG of six related muscles were measured during the tasks. Assuming that the EMG reflects the corresponding muscle stiffness, the joint stiffness was predicted from the EMG by using a two-link six-muscle arm model and a constrained least-square-error regression method. Using the parameters estimated in this regression, single-joint stiffness (diagonal terms of the joint-stiffness matrix) was decomposed successfully into biarticular and monoarticular muscle components. Although biarticular muscles act on both shoulder and elbow, they were found to covary strongly with elbow monoarticular muscles. The preferred force directions of biarticular muscles were biased to the directions of elbow monoarticular muscles. Namely, the elbow joint is regulated by the simultaneous activation of monoarticular and biarticular muscles, whereas the shoulder joint is regulated dominantly by monoarticular muscles. These results suggest that biarticular muscles are innervated mainly to control the elbow joint during static force-regulation tasks. In addition, muscle regulation mechanisms for static force control tasks were found to be quite different from those during movements previously reported. The elbow single-joint stiffness was always higher than cross-joint stiffness (off-diagonal terms of the matrix) in static tasks while elbow single-joint stiffness is reported to be sometimes as small as cross-joint stiffness during movement. That is, during movements, the elbow monoarticular muscles were occasionally not activated when biarticular muscles were activated. In static tasks, however, monoarticular muscle components in single-joint stiffness were increased considerably whenever biarticular muscle components in single- and cross-joint stiffness increased. These observations suggest that biarticular muscles are not simply coupled with the innervation of elbow monoarticular muscles but also are regulated independently according to the required task. During static force-regulation tasks, covariation between biarticular and elbow monoarticular muscles may be required to increase stability and/or controllability or to distribute effort among the appropriate muscles.
40
Sjøgaard, Gisela, Bente R. Jensen, Alan R. Hargens, and Karen Søgaard. "Intramuscular pressure and EMG relate during static contractions but dissociate with movement and fatigue." Journal of Applied Physiology 96, no. 4 (April 2004): 1522–29. http://dx.doi.org/10.1152/japplphysiol.00687.2003.
Full textAbstract:
Intramuscular pressure (IMP) and electromyography (EMG) mirror muscle force in the nonfatigued muscle during static contractions. The present study explores whether the constant IMP-EMG relationship with increased force may be extended to dynamic contractions and to fatigued muscle. IMP and EMG were recorded from shoulder muscles in three sessions: 1) brief static arm abductions at angles from 0 to 90°, with and without 1 kg in the hands; 2) dynamic arm abductions at angular velocities from 9 to 90°/s, with and without 1 kg in the hands; and 3) prolonged static arm abduction at 30° for 30 min followed by recovery. IMP and EMG increased in parallel with increasing shoulder torque during brief static tasks. During dynamic contractions, peak IMP and EMG increased to values higher than those during static contractions, and EMG, but not IMP, increased significantly with speed of abduction. In the nonfatigued supraspinatus muscle, a linear relationship was found between IMP and EMG; in contrast, during fatigue and recovery, significant timewise changes of the IMP-to-EMG ratio occurred. The results indicate that IMP should be included along with EMG when mechanical load sharing between muscles is evaluated during dynamic and fatiguing contractions.
41
Shiao, Yaojung, and Thang Hoang. "Exercise Condition Sensing in Smart Leg Extension Machine." Sensors 22, no. 17 (August 23, 2022): 6336. http://dx.doi.org/10.3390/s22176336.
Full textAbstract:
Skeletal muscles require fitness and rehsabilitation exercises to develop. This paper presents a method to observe and evaluate the conditions of muscle extension. Based on theories about the muscles and factors that affect them during leg contraction, an electromyography (EMG) sensor was used to capture EMG signals. The signals were applied by signal processing with the wavelet packet entropy method. Not only did the experiment follow fitness rules to obtain correct EMG signal of leg extension, but the combination of inertial measurement unit (IMU) sensor also verified the muscle state to distinguish the muscle between non-fatigue and fatigue. The results show the EMG changing in the non-fatigue, fatigue, and calf muscle conditions. Additionally, we created algorithms that can successfully sense a user’s muscle conditions during exercise in a leg extension machine, and an evaluation of condition sensing was also conducted. This study provides proof of concept that EMG signals for the sensing of muscle fatigue. Therefore, muscle conditions can be further monitored in exercise or rehabilitation exercise. With these results and experiences, the sensing methods can be extended to other smart exercise machines in the future.
42
Leisman, Gerald, Robert Zenhausern, Avery Ferentz, Tesfaye Tefera, and Alexander Zemcov. "Electromyographic Effects of Fatigue and Task Repetition on the Validity of Estimates of Strong and Weak Muscles in Applied Kinesiological Muscle-Testing Procedures." Perceptual and Motor Skills 80, no. 3 (June 1995): 963–77. http://dx.doi.org/10.2466/pms.1995.80.3.963.
Full textAbstract:
The study investigated the effects of fatigue and task repetition on the relationship between integrated electromyogram and force output during subjective clinical testing of upper extremity muscles. Muscles were studied under two conditions differing in the nature and duration of constant force production (SHORT-F) and (LONG-F). The findings included a significant relationship between force output and integrated EMG, a significant increase in efficiency of muscle activity with task repetition, and significant difference between Force/integrated EMG ratios for muscles labeled “Strong” and “Weak” in the LONG-F condition. This supports Smith's 1974 notion that practice results in increased muscular efficiency. With fatigue, integrated EMG activity increased strongly and functional (force) output of the muscle remained stable or decreased. Fatigue results in a less efficient muscle process. Muscles subjectively testing “Weak” or “Strong” yield effects significantly different from fatigue.
43
Brambilla, Cristina, and Alessandro Scano. "The Number and Structure of Muscle Synergies Depend on the Number of Recorded Muscles: A Pilot Simulation Study with OpenSim." Sensors 22, no. 22 (November 8, 2022): 8584. http://dx.doi.org/10.3390/s22228584.
Full textAbstract:
The muscle synergy approach is used to evaluate motor control and to quantitatively determine the number and structure of the modules underlying movement. In experimental studies regarding the upper limb, typically 8 to 16 EMG probes are used depending on the application, although the number of muscles involved in motor generation is higher. Therefore, the number of motor modules may be underestimated and the structure altered with the standard spatial synergy model based on the non-negative matrix factorization (NMF). In this study, we compared the number and structure of muscle synergies when considering 12 muscles (an “average” condition that represents previous studies) and 32 muscles of the upper limb, also including multiple muscle heads and deep muscles. First, we estimated the muscle activations with an upper-limb model in OpenSim using data from multi-directional reaching movements acquired in experimental sessions; then, spatial synergies were extracted from EMG activations from 12 muscles and from 32 muscles and their structures were compared. Finally, we compared muscle synergies obtained from OpenSim and from real experimental EMG signals to assess the reliability of the results. Interestingly, we found that on average, an additional synergy is needed to reconstruct the same R2 level with 32 muscles with respect to 12 muscles; synergies have a very similar structure, although muscles with comparable physiological functions were added to the synergies extracted with 12 muscles. The additional synergies, instead, captured patterns that could not be identified with only 12 muscles. We concluded that current studies may slightly underestimate the number of controlled synergies, even though the main structure of synergies is not modified when adding more muscles. We also show that EMG activations estimated with OpenSim are in partial (but not complete) agreement with experimental recordings. These findings may have significative implications for motor control and clinical studies.
44
JUNG, CHAN YONG, JUN-SIK PARK, YONGHYUN LIM, YOUNG-BEOM KIM, KWAN KYU PARK, JE HEON MOON, JOO-HO SONG, and SANGHOON LEE. "ESTIMATING FATIGUE LEVEL OF FEMORAL AND GASTROCEMIUS MUSCLES BASED ON SURFACE ELECTROMYOGRAPHY IN TIME AND FREQUENCY DOMAIN." Journal of Mechanics in Medicine and Biology 18, no. 05 (August 2018): 1850042. http://dx.doi.org/10.1142/s0219519418500422.
Full textAbstract:
This paper presents a new method for estimating muscle fatigue level based on surface electromyography (EMG) of femoral and gastrocnemius muscles during repetitive motions with various load. The relationship between fatigue level and EMG signals was examined through repetitive movements of the femoral and gastrocnemius muscles with the use of leg extension and squat machines. The fatigue level was based on the maximum voluntary contraction (MVC) levels with various loads. The integrated EMG (IEMG) value and the mean frequency value for each load cycle were obtained through the surface EMG signal. This work presents a global EMG index map by using the new analytical technique based on the relationship between the average IEMG and mean power frequency (MPF) values. The proposed method enables simultaneous estimation of muscle fatigue level and force using real-time EMG signals from the femoral and gastrocnemius muscles.
45
Omari, Taher I., Corinne A. Jones, Michael J. Hammer, Charles Cock, Philip Dinning, Lukasz Wiklendt, Marcello Costa, and Timothy M. McCulloch. "Predicting the activation states of the muscles governing upper esophageal sphincter relaxation and opening." American Journal of Physiology-Gastrointestinal and Liver Physiology 310, no. 6 (March 15, 2016): G359—G366. http://dx.doi.org/10.1152/ajpgi.00388.2015.
Full textAbstract:
The swallowing muscles that influence upper esophageal sphincter (UES) opening are centrally controlled and modulated by sensory information. Activation and deactivation of neural inputs to these muscles, including the intrinsic cricopharyngeus (CP) and extrinsic submental (SM) muscles, results in their mechanical activation or deactivation, which changes the diameter of the lumen, alters the intraluminal pressure, and ultimately reduces or promotes flow of content. By measuring the changes in diameter, using intraluminal impedance, and the concurrent changes in intraluminal pressure, it is possible to determine when the muscles are passively or actively relaxing or contracting. From these “mechanical states” of the muscle, the neural inputs driving the specific motor behaviors of the UES can be inferred. In this study we compared predictions of UES mechanical states directly with the activity measured by electromyography (EMG). In eight subjects, pharyngeal pressure and impedance were recorded in parallel with CP- and SM-EMG activity. UES pressure and impedance swallow profiles correlated with the CP-EMG and SM-EMG recordings, respectively. Eight UES muscle states were determined by using the gradient of pressure and impedance with respect to time. Guided by the level and gradient change of EMG activity, mechanical states successfully predicted the activity of the CP muscle and SM muscle independently. Mechanical state predictions revealed patterns consistent with the known neural inputs activating the different muscles during swallowing. Derivation of “activation state” maps may allow better physiological and pathophysiological interpretations of UES function.
46
Gillis, G. B. "Neuromuscular control of anguilliform locomotion: patterns of red and white muscle activity during swimming in the american eel anguilla rostrata." Journal of Experimental Biology 201, no. 23 (December 1, 1998): 3245–56. http://dx.doi.org/10.1242/jeb.201.23.3245.
Full textAbstract:
Two areas that have received substantial attention in investigations of muscle activity during fish swimming are (1) patterns of fiber type recruitment with swimming speed and (2) the timing of muscle activation in relation to muscle strain. Currently, very little is known about either of these areas in eels, which represent an extreme body form among fishes and utilize a mode of locomotion found at one end of the undulatory spectrum(anguilliform locomotion). To assess how this swimming mode and body form influence the neuromuscular control of swimming, I recorded electromyographic data from red and white muscle at four positions, 0.3L,0.45L, 0.6L and 0.75L, where L is body length, in eels (Anguilla rostrata)simultaneously video-taped (250 fields s-1) swimming at three speeds, 0.5,0.75 and 1.0 L s-1. As in other fish, exclusively red muscle is used at slow swimming speeds and white muscle is additionally recruited at higher swimming speeds. However, this study also revealed a novel posterior-to-anterior pattern of muscle recruitment with increasing swimming speed. At slow speeds, anteriorly located muscles are never active, muscle strain is negligible and forward thrust must be generated by posterior muscles. As speed increases, more anterior muscles are additionally recruited. Electromyogram (EMG) burst durations typically occupy between 0.2 and 0.3 undulatory cycles, irrespective of speed or position. EMG burst intensity increases significantly with swimming speed. The onset of EMG activity typically occurred near the end of muscle lengthening, whereas the offset of EMG activity occurred during shortening(typically before the muscle's return to resting length). There was a significant shift in red muscle onset times such that anterior muscles were typically active later in their strain cycle than posterior muscles. When red muscle activity patterns across various fish taxa are compared,differences in propulsive wavelength among species are related to differences in muscle activity, providing insight into the underlying neuromuscular bases of differences among undulatory swimming modes.
47
Abdul Malik, N., Z. Wahid, A. F. Zulkipili, S. Noorjannah Ibrahim, T. S. Gunawan, and Sheroz Khan. "Investigation of lower limb’s muscles activity during performance of salat between two age groups." Indonesian Journal of Electrical Engineering and Computer Science 14, no. 2 (May 1, 2019): 608. http://dx.doi.org/10.11591/ijeecs.v14.i2.pp608-617.
Full textAbstract:
Muscles play an important role in the movement of limbs. They undergo contraction to straighten or to bend a joint for the limbs to move. There are many factors that can affect muscle activity. Age could be one of the possible factors affecting muscle activity. The purpose of this study was to investigate the lower limb’s muscles activity during performance of <em>salat</em> between two age groups. The lower limb’s muscles investigated were Gastrocnemius (GAS), Biceps Femoris (BF), Tibialis Anterior (TA) and Rectus Femoris (RF). The postures involve are standing, bowing, prostrating and sitting. The electromyography (EMG) signals of the muscles were measured using the technique of surface EMG (sEMG). The signals were acquired by using Delsys Bagnoli™ Desktop sEMG system and EMGworks®. Ten healthy subjects from two age groups were recruited in this study. The first group consists of five males aged between 20 to 29 while the second group consists of five males aged above 40. The raw EMG signals acquired were analyzed and the EMG envelopes were developed using MATLAB. The averaged RMS values of EMG for each muscle were also calculated. Analysis of variance (ANOVA) of the EMGs was obtained by using <em>F</em>-test. Further investigation of the variance was performed by using Tukey comparison. From the results, the most active muscle during the performance of <em>salat</em> is BF while the less active muscle is GAS for both age groups. The statistical result show that there is no difference in the muscle activity pattern between the two age groups but there is significant difference among the muscles investigated.
48
Simoneau, Guy G., Richard W. Marklin, and Joseph E. Berman. "Effect of Computer Keyboard Slope on Wrist Position and Forearm Electromyography of Typists Without Musculoskeletal Disorders." Physical Therapy 83, no. 9 (September 1, 2003): 816–30. http://dx.doi.org/10.1093/ptj/83.9.816.
Full textAbstract:
Background and Purpose. Positioning a computer keyboard with a downward slope reduces wrist extension needed to use the keyboard and has been shown to decrease pressure in the carpal tunnel. However, whether a downward slope of the keyboard reduces electromyographic (EMG) activity of the forearm muscles, in particular the wrist extensors, is not known. Subjects and Methods. Sixteen experienced typists participated in this study and typed on a conventional keyboard that was placed on slopes at angles of 7.5, 0, −7.5, and −15 degrees. Electromyographic activity of the extensor carpi ulnaris (ECU), flexor carpi ulnaris (FCU), and flexor carpi radialis (FCR) muscles was measured with surface electrodes, while the extension and ulnar deviation angles of the right and left wrists were measured with electrogoniometers. Results. Wrist extension angle decreased from approximately 12 degrees of extension while typing on a keyboard with a 7.5-degree slope to 3 degrees of flexion with the keyboard at a slope of −15 degrees. Although the differences were in the range of 1% to 3% of maximum voluntary contraction (MVC), amplitude probability distribution function (APDF) of root-mean-square EMG data points from the ECU, FCU, and FCR muscles varied across keyboard slopes. Discussion and Conclusion. Wrist extension decreased as the keyboard slope decreased. Furthermore, a slight decrease in percentage of MVC of the ECU muscle was noted as the keyboard slope decreased. Based on biomechanical modeling and published work on carpal tunnel pressure, both of these findings appear to be positive with respect to comfort and fatigue, but the exact consequences of these findings on the reduction or prevention of injuries have yet to be determined. The results may aid physical therapists and ergonomists in their evaluations of computer keyboard workstations and in making recommendations for interventions with regard to keyboard slope angle.
49
DiMarco, A. F., J. R. Romaniuk, and G. S. Supinski. "Parasternal and external intercostal responses to various respiratory maneuvers." Journal of Applied Physiology 73, no. 3 (September 1, 1992): 979–86. http://dx.doi.org/10.1152/jappl.1992.73.3.979.
Full textAbstract:
Recent studies suggest that the external intercostal (EI) muscles of the upper rib cage, like the parasternals (PA), play an important ventilatory role, even during eupneic breathing. The purpose of the present study was to further assess the ventilatory role of the EI muscles by determining their response to various static and dynamic respiratory maneuvers and comparing them with the better-studied PA muscles. Applied interventions included 1) passive inflation and deflation, 2) abdominal compression, 3) progressive hypercapnia, and 4) response to bilateral cervical phrenicotomy. Studies were performed in 11 mongrel dogs. Electromyographic (EMG) activities were monitored via bipolar stainless steel electrodes. Muscle length (percentage of resting length) was monitored with piezoelectric crystals. With passive rib cage inflation produced either with a volume syringe or abdominal compression, each muscle shortened; with passive deflation, each muscle lengthened. During eupneic breathing, each muscle was electrically active and shortened to a similar degree. In response to progressive hypercapnia, peak EMG of each intercostal muscle increased linearly and to a similar extent. Inspiratory shortening also increased progressively with increasing PCO2, but in a curvilinear fashion with no significant differences in response among intercostal muscles. In response to phrenicotomy, the EMG and degree of inspiratory shortening of each intercostal muscle increased significantly. Again, the response among intercostal muscles was not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)
50
Ladin, Z., and K. M. Neff. "Testing of a Biomechanical Model of the Lumbar Muscle Force Distribution Using Quasi-Static Loading Exercises." Journal of Biomechanical Engineering 114, no. 4 (November 1, 1992): 442–49. http://dx.doi.org/10.1115/1.2894093.
Full textAbstract:
The study of lumbar muscle force distribution in response to externally applied loads is based on the introduction of biomechanical models of the lumbar region. The evaluation of such models requires the execution of loading exercises while monitoring the EMG activity of certain lumbar muscles. This work uses muscle activity maps as the major design tool of such exercises, provided that the subject is constrained to an upright erect posture. The maps describe the predicted muscle force for a given combination of externally applied bending moments. A series of shoulder adduction exercises were designed and the EMG signals of eight lumbar muscles were measured while subjects performed the exercises. The results show good agreement between the model predictions and the EMG measurements, especially when the load and the muscle were contralateral to one another.