The influence of myosin heavy chain isoform content on mechanical behavior of the vastus lateralis in vivo

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• 作者：Michael A. Trevino^a ; ^{mtrevino@ku.edu" class="auth_mail" title="E-mail the corresponding author}Author Vitae ; Trent J. Herda^a ; ^{t.herda@ku.edu" class="auth_mail" title="E-mail the corresponding author} ; Andrew C. Fry^b ; ^{acfry@ku.edu" class="auth_mail" title="E-mail the corresponding author} ; Philip M. Gallagher^b ; ^{philku@ku.edu" class="auth_mail" title="E-mail the corresponding author} ; John P. Vardiman^c ; ^{pvardiman@ksu.edu" class="auth_mail" title="E-mail the corresponding author} ; Eric M. Mosier^a ; ^{emosier4@ku.edu" class="auth_mail" title="E-mail the corresponding author} ; Jonathan D. Miller^a ; ^{j980m842@ku.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Isometric trapezoidal muscle action ; Log-transform model ; Mechanomyography ; Myosin heavy chain ; Motor unit control ; Vastus lateralis
• 刊名：Journal of Electromyography and Kinesiology
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：28
• 期：Complete
• 页码：143-151
• 全文大小：972 K

文摘

This study examined correlations between type I percent myosin heavy chain isoform content (%MHC) and mechanomyographic amplitude (MMG_RMS) during isometric muscle actions. Fifteen (age = 21.63 ± 2.39) participants performed 40% and 70% maximal voluntary contractions (MVC) of the leg extensors that included increasing, steady force, and decreasing segments. Muscle biopsies were collected and MMG was recorded from the vastus lateralis. Linear regressions were fit to the natural-log transformed MMG_RMS–force relationships (increasing and decreasing segments) and MMG_RMS was selected at the targeted force level during the steady force segment. Correlations were calculated among type I%MHC and the b (slopes) terms from the MMG_RMS–force relationships and MMG_RMS at the targeted force. For the 40% MVC, correlations were significant (P < 0.02) between type I%MHC and the b terms from the increasing (r = −0.804) and decreasing (r = −0.568) segments, and MMG_RMS from the steady force segment (r = −0.606). Type I%MHC was only correlated with MMG_RMS during the steady force segment (P = 0.044, r = −0.525) during the 70% MVC. Higher type I%MHC reduced acceleration in MMG_RMS (b terms) during the 40% MVC and the amplitude during the steady force segments. The surface MMG signal recorded during a moderate intensity contraction provided insight on the contractile properties of the VL in vivo.