筋収縮力と筋線維伝導速度(3部運動の調整)

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The average conduction velocity of human skeletal muscle fibers measured with multicontact surface electrodes has been reported to increase with the muscular contraction force. This increase of the conduction velocity is considered to be a manifestation of the size principle of motor units: the larger motor units with higher recruitment thresholds tend to have higher conduction velocities. However, this increase was not observed in all the muscles studied. The present study is designed to further clarify this relationship between the contraction force and the average muscle fiber conduction velocity. The subjects were requested to track the force trajectory presented on a CRT screen. The force trajectory had three plateaus, which lasted 2s each and were connected by straight lines. The first and third plateaus of the force trajectory corresponded to the sustained contraction of 50% of the maximal voluntary contraction (MVC), which was used as the reference. The second plateau corresponded to a variable target contraction force that was set at the four levels of 30%, 50%, 70% and 90% MVC. The biceps brachii, the tibialis anterior and the vastus lateralis of five healthy males were studied. The average muscle fiber conduction velocity was calculated by the cross-correlation between two myoelectric signals derived from positions 15mm apart along the muscle fibers. In some recordings, the conduction velocity at the 50% MVC after the target contraction decreased significantly from the velocity at the first 50% MVC reference contraction. This decrease was most prominent in the biceps brachii and is considered to be a manifestation of muscular fatigue. The recordings that showed no decrease of the conduction velocity after the target contraction indicated a positive correlation between the contraction force and the conduction velocity; that is, the conduction velocity had higher value during the contraction of larger force. This result indicates a tendency for the conduction velocity to increase with the contraction force, as previously reported, but the decrease of the velocity caused by muscular fatigue may hide this tendency.
バイオメカニズム学会の論文
1992-05-20

筋収縮力と筋線維伝導速度(3部運動の調整)

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筋収縮力と筋線維伝導速度(3部 運動の調整)

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筋収縮力と筋線維伝導速度(3部運動の調整)