老人隨著生理狀況退化、經常罹患多重慢性疾病、身體活動量減少，進而加速肌肉量的減少而造成肌少症。近年來的研究發現肌少症為老人失能、跌倒、功能退化、住院、甚至死亡等的危險因子。規律的身體活動或運動有益健康，則可降低心臟病死亡的危險，減少糖尿病、高血壓、大腸癌等的發生，協助控制體重，維持健康的骨骼、減少憂鬱及焦慮，增加幸福感。老人適度地參與規律運動，除了上述促進健康的好處外，更可協助老人維持身體之活動能力、避免跌倒、減少骨折、增加獨立自主生活的能力。老人接受阻力運動訓練時可增進肌力以及肌肉量。本文期望藉由簡介身體活動及肌少症，來提升臨床醫護人員對肌少症及老人運動處方的進一步認識。未來方能針對高危險群，及早提供身體活動評估及介入措施，以降低失能以及相關不良結果發生。

Sarcopenia, characterized by age-related decline of skeletal muscle plus low muscle strength and/or physical performance, is correlated with the comorbidity and physical inactivity in the older adults. Previous studies have demonstrated the association of sarcopenia with adverse health outcomes, such as falls, disability, hospital admission, long-term care placement, poorer quality of life, and mortality. Meanwhile accumulating evidences have supported the inverse relationship between regular physical activity and premature mortality, cardiovascular disease/coronary heart disease, hypertension, stroke, osteoporosis, type 2 diabetes mellitus, metabolic syndrome, obesity, colon cancer, breast cancer, depression, functional health, falls, and cognitive function. In addition, regular physical activity enhances physical function, independent living, and feelings of well-being, and reduces risk of falls and injuries from falls in older adults. Resistance exercise is also effective in improving muscles strength and eliciting gains in muscle mass in the elderly. In this article, we briefly review physical activity and sarcopenia in the elderly. We hope by increasing the awareness among professionals, early detection of sarcopenia and physical inactivity, and timely physical activity intervention could be provided to decrease adverse outcome for this fast growing population.