大腿四頭筋の筋疲労による筋活動比の変化について

概要

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The aim of this study was to investigate the multi-muscle fatigue patterns in Rectus Femoris (RF), Vastus Medialis (VM), and Vastus Lateralis (VL). Sixteen healthy subjects performed isometric knee extensions at 25%, 50%, and 75% of maximum voluntary contraction (MVC). Surface electromyographic activity (EMG) was recorded from RF, VM, and VL during 40 sec of isometric contraction. Median Power Frequency (MDPF) and Normalized EMG amplitude (%AEMG) were calculated from EMG data. RF showed a significant decrease in MDPF at every contraction level (p<0.001), but VM and VL showed significant decreases only at 75% MVC (p<0.0l). The MDPF coefficients of regression showed RF declined significant greater than VM and VL at 50% and 75% MVC (p<0.05). RF didn't show a significant change in %AEMG at 25% MVC, even though VM and VL showed significant increases at every contraction level (p<0.05). RF/VM and RF/VL ratios increased during fatiguing tasks at 25% and 50% MVC (p<0.05). These results show the difference in fatigue patterns in RF and monoarticular muscles. It seems that increased activity of VM and VL compensate for a fall in RF output during muscle fatigue. This could represent an example of muscle synergy during muscle fatigue.