台湾の筋肉量・身体機能・握力

台湾での加齢による筋肉量減少と身体機能の関連をみた報告を紹介します。

Liu LK, Lee WJ, Liu CL, Chen LY, Lin MH, Peng LN, Chen LK.　Age-related skeletal muscle mass loss and physical performance in Taiwan: Implications to diagnostic strategy of sarcopenia in Asia.　Geriatr Gerontol Int. 2013 Mar 3. doi: 10.1111/ggi.12040. [Epub ahead of print]

筋肉量はDEXAで測定しています。骨格筋量の指標として除脂肪体重÷身長÷身長(LBM/ht2 )、四肢骨格筋量÷身長÷身長(ASM/ht2 )、骨格筋指数 (SMI%)の3つを計算して、身体機能との関連を検討しました。

結果ですが、加齢は身体機能低下と関連し、ASM/ht2とLBM/ht2は加齢で低下しましたがSMI%は低下しませんでした。男性では歩行速度低下との関連は、SMI%よりASM/ht2のほうが高かったです。

女性ではASM/ht2、LBM/ht2、SMI%のいずれも歩行速度低下と有意な関連を認めませんでした。一方、握力は男女とも筋肉量減少（ASM/ht2とLBM/ht2のみ）と強い相関を認めました。

以上より、骨格筋量は握力とは強い相関を認めるが、歩行速度との相関はあまり強くないという結論です。アジア人では骨格筋量の指標として四肢骨格筋量÷身長÷身長(ASM/ht2 )が最も望ましく、身体機能の評価は骨格筋量の測定とは別に必要です。

サルコペニアの診断基準はまだ統一されていませんが、やはり筋肉量、筋力（握力）、身体機能（歩行速度など）の3項目の評価は行うべきでしょう。DEXAで筋肉量を評価できる場合には、四肢骨格筋量÷身長÷身長(ASM/ht2 )を計算するのがよさそうです。

Abstract

AIM:

Skeletal muscle loss is a common feature of aging, and is associated with unfavorable outcomes. Although several indexes of skeletal muscle mass measurement have been developed, the most optimal index for sarcopenia diagnosis among Asian populations has remained unclear. The present study aimed to evaluate the relationship between skeletal muscle mass and physical performance among community-dwelling people in Taiwan.

METHODS:

Data of the I-Lan Longitudinal Aging Study (ILAS) were retrieved for study. Comparisons between demographic profiles, physical performance and skeletal muscle mass (measured by dual-energy X-ray absorptiometry) were carried out. Skeletal muscle mass expressed by lean body mass divided by squared height (LBM/ht2 ), appendicular muscle mass divided by squared height (ASM/ht2 ) and percent skeletal muscle index (SMI%) were compared between measurements of physical performance.

RESULTS:

Overall, the data of 532 participants (mean age 64.6 ± 9.5 years, male 53.0%) were retrieved for analysis. Age was associated with poorer physical performance, and decreased ASM/ht2 and LBM/ht2 , but not SMI%. Skeletal muscle mass (SMI%) was less significantly related to slow walking speed than ASM/ht2 in men. In women, all three muscle indexes showed no significant association between slow walking speed. In contrast, low handgrip strength was strongly associated with decreased skeletal muscle mass (measured by ASM/ht2 and LBM/ht2 , but not SMI%) in both men and women.

CONCLUSIONS:

Skeletal muscle mass was significantly associated with handgrip strength along with aging, but the association of skeletal muscle mass and walking speed was less significant. In sarcopenia diagnosis among Asian populations, ASM/ht2 should be the most suitable index for skeletal muscle mass measurements, and physical performance should be measured universally beyond measurements of skeletal muscle mass.