骨格筋の老化

Aging and homeostasis. Aging of skeletal muscle.

　加齢に伴い，骨格筋のインスリン抵抗性やサルコペニアが誘導され，骨格筋の老化が生じる。前者は，加齢に伴いミトコンドリア機能が低下することが原因の一つであることが示唆され，後者はそれ以外にも内分泌学的な機能異常，神経的な機序，栄養不足や不活動などによる廃用の要素が複雑に関与している。運動はミトコンドリアの活性や量を高め，加齢に伴う骨格筋のインスリン抵抗性に対して予防的に働くことや，サルコペニアの予防・改善にも有用であることが示唆されている。一方，栄養補給に関しては，アミノ酸摂取によるサルコペニアの改善効果も報告されている。

　With aging, insulin resistance and sarcopenia in skeletal muscle are induced, resulting in skeletal muscle aging. It is suggested that the former is one of the reasons that mitochondrial function decreases with aging, and the latter is due to endocrinologic dysfunction, neurological mechanism, nutritional deficiency and inactivity such as waste are complicatedly involved. Also, as sarcopenia progresses, the amount of physical activity further decreases, and it is also assumed that insulin resistance and sarcopenia progress synergistically. It is suggested that exercise enhances the activity and amount of mitochondria and works preventively against insulin resistance in skeletal muscle accompanying aging and it also works for prevention and amelioration of sarcopenia. On the other hand, as for nutritional supplementation, it has been reported that it works for improving sarcopenia by amino acid ingestion.