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

Journal of Biomechanics
Trent J HerdaAndrew C Fry

Abstract

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 < 0.05). The greater slopes likely reflected larger higher-threshold MUs for the males. The mCSAs and slopes from the relationships were strongly correlated with isometric and isokinetic peak torque and isokinetic mean power (r = 0.78-0.82), however, type I %MHC isoform was only moderately correlated with isometric peak torque (r = -0.54). The results indicated that sex-related differences in muscu...Continue Reading

Citations

May 16, 2019·European Journal of Applied Physiology·Zachary M GillenJoel T Cramer
Oct 24, 2020·The Journal of Sports Medicine and Physical Fitness·Michael T Lane, Andrew C Fry
May 1, 2021·Exercise and Sport Sciences Reviews·Kemal S Türker

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