長距離ランナーにおける大腿二頭筋反復随意収縮後の運動野の興奮性変化

概要

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In the present study, excitability changes in the motor cortex innervating the upper leg muscle, biceps femoris (BF), after repeated voluntary knee flexions, 1 stroke every 2s, were investigated in both highly trained long-distance runners (LDR) and normal subjects. Subjects took a prone position and a double corn coil was used for transcranial magnetic stimulation (TMS). The coil was placed in the appropriate position on the subject's head to evoke motor evoked potentials (MEP) from the BF during knee flexion at 45 degree against a horizontal plane. We could not detect any changes in MEP in either group after repeated voluntary knee flexions for 5, 10, and 15min, including passive knee flexions for 15min. However, after a 30-min training session, MEP was significantly increased in the LDR only without any changes of background EMG during 100ms prior to the magnetic stimulation showing that muscle fatigue had not occurred. This showed that the plasticity of the motor cortex innervating BF, which may contribute to the driving force of running, is the same as that of the hand-motor cortex. Furthermore, this plasticity was only observed in the highly trained LDR, suggesting that long-term plasticity may be a factor contributing to short-term plasticity.
2010-07-31