[Relationship between physical activity and muscle mass loss among people aged 60 and above in 15 provinces of China in 2015].

Objective: To analyze the relationship between physical activity and muscle mass loss among Chinese elderly aged 60 years and above in 15 provinces.

Methods: Data was collected from 2015 China Nutritional Transition Cohort Study. Information on demographic characteristics and physical activity was investigated by questionnaire. Dietary intake was estimated from three consecutive 24-h recalls for each individual. Appendicular skeletal muscle mass(ASM) was assessed using the bioelectrical impedance analysis(BIA). Skeletal muscle mass(SMI) loss was diagnosed according Asian working group of sarcopenia(AWGS) 2019 recommendation(male: SMI <7.0 kg/m~2, female: <5.7 kg/m~2). A total of 4565 participants aged 60 years and above from 15 provinces in China with complete information were included in the final analysis. Different domains(occupational, domestic, travel and leisure), light physical activity(<3.0 METs), moderate physical activity(3.0-5.9 METs) and vigorous physical activity(≥6.0 METs) of physical activity among elderly adults were evaluated. Logistic multilevel model was used to analyze the relationship between low muscle mass and different intensity of physical activity duration.

Results: Among all participants aged 60 years and above in 15 provinces of China in 2015, women's participation rate in domestic physical activity was 91.7%, which was higher than men's rate of 62.3%. However, men's participation rate in occupational, travel and leisure physical activity were higher than those of women. The participation rate, duration of light physical activity and moderate physical activity were higher in women than in men(light physical activity: female duration 11.0 h/week vs. male duration 3.5 h/week; female participation rate 89.9% vs. male participation rate 62.8%; moderate physical activity: female duration 7.0 h/week vs. male duration 4.7 h/week; female participation rate 90.6% vs. male participation rate 75.2%). The median vigorous physical activity was 0 h/week in both male and female group. The prevalence of muscle mass loss was 13.9% among subjects. The median weekly light physical activity and moderate physical activity in muscle mass loss group were 5.8 h and 4.7 h, which were lower than in non-muscle mass loss group(9.3 h and 6.0 h). The OR of muscle mass lass was 0.71(95%CI 0.42-0.98, P<0.05) for the male with 3.5-6.9 hours of moderate physical activity per week, compared to moderate physical activity less than 3.5 h/week. And OR of the female was 0.67(95%CI 0.47-0.95, P<0.05).

Conclusion: The vast majority of physical activity in China among the elderly is domestic and light physical activity. Light physical activity and moderate physical activity duration increments in female and moderate physical activity duration increments in male were associated with decreased risk of muscle mass loss.