Relationship between Nonexercise Activity Thermogenesis and Calf Circumference in Older Women

Purpose: Frailty is a state of declined vitality of the body and mind with age in which life functions are impaired. In addition, there is a difference in the susceptibility of older women to frailty compared with that of older men. Therefore, assessing and encouraging physical activity in older adults before they become frail is essential. We aimed to clarify the relationship between calf circumference and body composition and assess the potential association between calf circumference and physical activity indices in older women. Methods: This cross-sectional study included 18 healthy older adults (age 69.0 ± 5.7 years). The physical characteristics, calf circumference, body composition, calf muscle thickness, and physical activity questionnaire that included items on exercise-related activity thermogenesis (EAT) and nonexercise activity thermogenesis (NEAT) were assessed. The association between calf circumference and these additional measures was examined. Results: Positive and significant correlations were found between the calf circumference and body weight, body mass index (BMI), skeletal muscle mass, skeletal muscle mass index, calf muscle thickness, total questionnaire score, and NEAT score (r = 0.66 - 0.87). However, no significant correlations were observed between the calf circumference and EAT scores. Conclusion: Calf circumference in older women may reflect NEAT activity. Improving NEAT activity is an important health-promoting factor in older women.