Abstract
BACKGROUND: Within-country studies show that physical activity is associated with better intrinsic capacity. OBJECTIVES: To examine whether the contribution of physical activity to intrinsic capacity varies between countries due to varying social determinants, and whether physical activity associates differently with only certain domains of intrinsic capacity. DESIGN: Prospective cohort studies. SETTING: Populations of the USA, UK, Europe, and China. PARTICIPANTS: Nationally representative samples of middle-aged and older adults who were interviewed every two or three years. MEASUREMENTS: Intrinsic capacity was assessed according to the following domains: locomotor, vitality, cognition, vision and hearing, and psychological health. Physical activity was defined as taking part in vigorous or moderate physical activity was more than weekly. RESULTS: Physical activity was associated with better intrinsic capacity in both genders in USA, UK, and Europe, but not in China. In these developed countries, physical activity was associated with all domains of intrinsic capacity, except for cognition in men in the UK. The largest effect sizes were observed in the domains of locomotion, psychological health, and vitality. In China, physical activity was significantly and positively associated with two domains of intrinsic capacity (vitality and locomotion) for men and women only in rural areas. CONCLUSIONS: Physical activity may contribute differently to intrinsic capacity, perhaps as a result of cultural and economic differences between countries.