Association between sarcopenia and higher-level functional capacity in daily living in community-dwelling elderly subjects in Japan

This study aimed to determine the association between sarcopenia, defined by muscle mass, muscle strength, and physical performance, and higher-level functional capacity in community-dwelling Japanese elderly people. Subjects were 1158 elderly, community-dwelling Japanese people aged 65 or older. We used bioelectrical impedance analysis to measure muscle mass, grip strength to measure muscle strength, and usual walking speed to measure physical performance. Sarcopenia was characterized by low muscle mass, plus low muscle strength or low physical performance. Subjects without low muscle mass, low muscle strength, and low physical performance were classified as "normal." Examination of higher-level functional capacity was performed using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC). The TMIG-IC is a 13-item questionnaire completed by the subject; it contains five questions on self-maintenance and four questions each on intellectual activity and social role. Sarcopenia was identified in 11.3% and 10.7% of men and women, respectively. The percentage of disability for instrumental activities of daily living (IADL) was 39.0% in men with sarcopenia and 30.6% in women with sarcopenia. After adjustment for age, in men, sarcopenia was significantly associated with IADL disability compared with intermediate and normal subjects. In women, sarcopenia was significantly associated with every subscale of the TMIG-IC disability compared with intermediate and normal subjects. This study revealed that sarcopenia, defined by muscle mass, muscle strength, and physical performance, had a significant association with disability in higher-level functional capacity in elderly Japanese subjects. Interventions to prevent sarcopenia may prevent higher-level functional disability among elderly people.