短期筋不活動によって生じる最大随意収縮力の低下機構

• 増田 正

  東京医科歯科大学

• 金子 文成

  独立行政法人産業技術総合研究所

• 横井 孝志

  独立行政法人産業技術総合研究所

• 山田 洋

  東海大学

• 木塚 朝博

  筑波大学

書誌事項

タイトル別名

• A MECHANISM FOR DETERIORATION IN THE MAXIMAL VOLUNTARY CONTRACTION CAUSED BY SHORT-TERM MUSCLE IMMOBILIZATION

抄録

The disuse syndrome is caused by low physical activity especially in the elderly. If muscles are not used for a long time, their strength will decrease. Weakened muscles accelerate reduced daily life activity. To overcome the disuse syndrome, appropriate training must be delivered with proper timing. The purpose of the present study was to clarify the mechanism of muscle deterioration at the beginning of the disuse syndrome. This kind of knowledge may contribute to developing training methods and training devices that can prevent the progress of the disuse syndrome. For this purpose, a model experiment was performed on ten healthy young adults. Their knee and ankle joints were immobilized in casts for one week. Before and after the immobilization, changes in their motor functions were measured. As an indication of the morphological changes, the muscle cross sectional area (CSA) was measured based on magnetic resonance images (MRIs). As a functional indication, the maximal voluntary contraction (MVC) torque of the ankle plantar flexion was measured. Since the MVC is affected both by the muscle itself and by the nervous system or the sensory feedback, the potential MVC and the EMG amplitude during the MVC were also measured. The potential MVC was estimated by the twitch interpolation method, which is an indicator of the muscle strength excluding the effect of the nervous system. The EMG was derived from the soleus and the gastroc-nemius and is an indicator of the activation from the nervous system. The CSA of the soleus showed no significant change after the immobilization. The ratio of the change was 100.3±1.8%, which was comparable to the variability of the measurement. In contrast, the MVC decreased to 82.7±11.8% (p<0.01, t-test). The potential MVC and the EMG amplitude also decreased to 84.5±17.9% and 83.6±18.6%, respectively. These results indicate that there exists a state at the beginning of the disuse syndrome, in which the muscle CSA looks normal but invisible deterioration proceeds in the muscle. The deterioration also occurs in the nervous system, which in conjunction with the deterioration in the muscle, causes the decrease in the MVC.

収録刊行物

• バイオメカニズム

  バイオメカニズム 17 29-35, 2004-08-25

  バイオメカニズム学会

詳細情報

• CRID: 1571135651948970752
• NII論文ID: 110004695678
• NII書誌ID: AN10286188
• 本文言語コード: ja
• データソース種別:
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