Muscular strength and power are correlated with motor unit action potential amplitudes, but not myosin heavy chain isoforms in sedentary males and females

It remains unclear if the sizes of higher-threshold motor units (MU) are associated with muscular strength and power. Therefore, the purpose of this study was to examine sex-related differences in muscle cross-sectional area (mCSA), percent myosin heavy chain (%MHC) isoform expression, and the MU ac...

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Bibliographic Details
Published in:Journal of biomechanics 2019-03, Vol.86, p.251-255
Main Authors: Herda, Trent J., Trevino, Michael A., Sterczala, Adam J., Miller, Jonathan D., Wray, Mandy E., Dimmick, Hannah L., Gallagher, Philip M., Fry, Andrew C.
Format: Article
Language:English
Subjects:
Action potential
Action Potentials - physiology
Adult
Algorithms
Amplitudes
Chains
Conflicts of interest
Correlation
Decomposition
Electromyography
EMG decomposition
Female
Females
Humans
Isoforms
Isokinetic
Male
Males
Motor unit action potential amplitude
Motor units
Motors
Muscle contraction
Muscle Contraction - physiology
Muscle cross-sectional area
Muscle Fibers, Skeletal - metabolism
Muscle strength
Muscle Strength - physiology
Muscle, Skeletal - diagnostic imaging
Muscle, Skeletal - physiology
Myosin
Myosin heavy chain
Myosin Heavy Chains - metabolism
Protein Isoforms
Quadriceps Muscle - physiology
Sedentary Behavior
Sex
Sex differences
Sex Factors
Slopes
Torque
Ultrasonic imaging
Ultrasonography
Ultrasound
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Summary:It remains unclear if the sizes of higher-threshold motor units (MU) are associated with muscular strength and power. Therefore, the purpose of this study was to examine sex-related differences in muscle cross-sectional area (mCSA), percent myosin heavy chain (%MHC) isoform expression, and the MU action potential amplitudes (MUAPAMPS)-recruitment threshold (RT) relationships of the vastus lateralis and isometric peak torque, isokinetic peak torque and mean power at 1.05 rad·s−1 of the leg extensors. Surface electromyographic decomposition techniques were used to quantify MUAPAMPS recorded during isometric muscle actions at 70% of maximal voluntary contractions and regressed against RTs with the slopes calculated. Ultrasound images were used to measure mCSA. Males had greater slopes from the MUAPAMP-RT relationship than the females (P 
ISSN:0021-9290
1873-2380
DOI:10.1016/j.jbiomech.2019.01.050