Is myoelectric activity distributed equally within the rectus femoris muscle during loaded, squat exercises?

Souza, Leonardo Mendes Leal de; Fonseca, Desirée Barros da; Cabral, Hélio da Veiga; Oliveira, Líliam Fernandes de; Vieira, Taian

doi:10.1016/j.jelekin.2017.01.003

Cited by 16 publications

(13 citation statements)

References 45 publications

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“…This agrees with findings from Watanabe et al [43], who have found that the muscle excitation of RF can be regionally activated (proximal, middle, and distal regions) and nonuniformly regulated during gait. Similar findings were also found in RF during squat [44]. According to Vieira et al [42], muscle excitation may be better assessed with multiple bipolar EMG electrodes or high-density EMG may than with only one bipolar EMG electrode.…”

Section: B Experiments Resultssupporting

confidence: 70%

Weight Distribution of a Knee Exoskeleton Influences Muscle Activities During Movements

et al. 2021

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Lower extremity powered exoskeletons help people with movement disorders to perform daily activities and are used increasingly in gait retraining and rehabilitation. Studies of powered exoskeletons often focus on technological aspects such as actuators, control methods, energy and effects on gait. Limited research has been conducted on how different mechanical design parameters can affect the user. In this paper, we study the effects of weight distributions of knee exoskeleton components on simulated muscle activities during three functional movements. Four knee exoskeleton CAD models were developed based on actual motor and gear reducer products. Different placements of the motor and gearbox resulted in different weight distributions. One unilateral knee exoskeleton prototype was fabricated and tested on 5 healthy subjects. Simulation results were compared to observed electromyography signals. Muscle activities varied among weight distributions and movements, wherein no one physical design was optimal for all movements. We describe how a powered exoskeleton's core components can be expected to affect a user's ability and performance. Exoskeleton physical design should ideally take the user's activity goals and ability into consideration.

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Section: B Experiments Resultssupporting

confidence: 70%

Weight Distribution of a Knee Exoskeleton Influences Muscle Activities During Movements

et al. 2021

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“…For the RF muscle, we recommend using two surface EMG electrode pairs, over the proximal and middle-distal regions, to assess RF muscle contributions to hip flexion and knee extension. Based on previous studies ( 23 , 36 , 58 , 85 , 86 ), surface electrode pairs at 20% and 50% or more distal sites along a line between the anterior superior iliac spine and superior edge of the patella from the proximal site would lead to neuromuscular activation of the RF muscle to mainly act as a hip flexor or knee extensor. Under fatiguing conditions, proximal electrodes would be expected to show greater adjustments in myoelectric activity during fatiguing contractions than middle-distal electrodes.…”

Section: Introductionmentioning

confidence: 99%

Novel Insights Into Biarticular Muscle Actions Gained From High-Density Electromyogram

Watanabe

Vieira

Gallina

et al. 2021

Exercise and Sport Sciences Reviews

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“…After that, monopolar signals were differentiated into 15 single‐differential EMGs and their root mean square (RMS) amplitude was computed over 90% of the duration of each eccentric and concentric phases identified during the whole exercise (Figure 2B). Specifically, the time interval considered to calculate RMS was defined within instants corresponding to 5% and 95% of the phase duration, and, thus, the periods including transitions between movement phases were discarded 5 . Only active channels , defined as channels detecting surface EMGs with RMS amplitude greater than 70% of the maximum amplitude across the linear array of electrodes, 27 were retained for further analysis (cf.…”

Section: Methodsmentioning

confidence: 99%

“…Inhomogeneous excitation of human skeletal muscles has been consistently reported in voluntary contractions 1‐5 . Compelling evidence indicates that such inhomogeneities could be explained by the excitation of muscle sub‐volumes according to differential, functional demands imposed by specific tasks or movement directions 3,6‐9 .…”

Section: Introductionmentioning

confidence: 99%

“…Inhomogeneous excitation of human skeletal muscles has been consistently reported in voluntary contractions. [1][2][3][4][5] Compelling evidence indicates that such inhomogeneities could be explained by the excitation of muscle sub-volumes according to differential, functional demands imposed by specific tasks or movement directions. 3,[6][7][8][9] Based on the detection of surface electromyograms (EMGs) from multiple skin regions, with a high-density EMG system, 10 for instance, Watanabe, Kouzaki, Moritani 11 demonstrated that proximal and distal regions of the bi-articular rectus femoris muscle showed higher EMG amplitude, respectively, during hip flexion and knee extension contractions, suggesting these regions have distinct functional roles.…”

Section: Introductionmentioning

confidence: 99%

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Non‐uniform excitation of the pectoralis major muscle during flat and inclined bench press exercises

Cabral

Souza

Oliveira

et al. 2021

Scandinavian Med Sci Sports

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Non‐physiological sources may lead to equivocal interpretation on the degree of muscle excitation from electromyograms (EMGs) amplitude. This presumably explains the contradictory findings regarding the effect of the bench press inclination on the pectoralis major (PM) activation pattern. To contend with these issues, herein we used high‐density surface EMG to investigate whether different PM regions are excited during the flat and 45° inclined bench press exercises. Single‐differential EMGs were collected from 15 regions along the PM cranio‐caudal axis, while 8 volunteers performed a set of the flat and 45° inclined bench press at 50% and 70% of 1 repetition maximum. The coefficient of variation, the range of motion, and the cycle duration were calculated from the barbell vertical position to assess the within‐subject consistency across cycles. The number of channels detecting the largest EMGs amplitude (active channels), their interquartile range, and their barycentre coordinate were assessed to characterize the EMG amplitude distribution within PM. No significant differences in the range of motion (p > 0.11), cycle duration (p > 0.28), number of active channels (p > 0.05), and interquartile range of active channels (p > 0.39) were observed between the two bench press inclinations. Conversely, the barycentre shifted toward the PM clavicular region (p < 0.001) when the bench press changed from flat to 45°. Our results revealed that greatest EMG amplitudes were concentrated at the PM sternocostal and clavicular heads when exercising in the flat and 45° inclined bench press, respectively. Performing the bench press exercise, with different postures, seem to demand the excitation of different PM regions.

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Is myoelectric activity distributed equally within the rectus femoris muscle during loaded, squat exercises?

Cited by 16 publications

References 45 publications

Weight Distribution of a Knee Exoskeleton Influences Muscle Activities During Movements

Weight Distribution of a Knee Exoskeleton Influences Muscle Activities During Movements

Novel Insights Into Biarticular Muscle Actions Gained From High-Density Electromyogram

Non‐uniform excitation of the pectoralis major muscle during flat and inclined bench press exercises

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