Cross-sectional interactive associations of physical activity and sedentary behaviour with physical capacity across adulthood.

BACKGROUND: The way physical activity (PA) and sedentary behaviour (SB) independently and interactively modify the age-related decline in physical capacity remains poorly understood. This cross-sectional study investigated the independent and interactive associations of PA and SB with physical function and performance throughout the adult life course. METHODS: Data from 499 community-dwelling adults (63% female) aged 20-92 years, involved in the INSPIRE Human Translational Cohort, were used in this cross-sectional study. Daily time spent on moderate-to-vigorous PA (MVPA, min/day) and SB (h/day) was measured with activPAL triaxial accelerometers. Physical function and performance were assessed through the measurement of the 4-m usual gait speed (m/s), handgrip strength (kg), lower-limb strength (isokinetic knee extension torque, N·m), estimated lower-limb power (five-time chair-rise test performance, s) and cardiorespiratory fitness (V̇O2max, mL/kg/min). Confounder-adjusted multiple linear and curvilinear regressions were performed to investigate how MVPA, SB and their interactions were associated with the physical outcomes (all square root-transformed except gait speed) throughout the adulthood spectrum. RESULTS: Interaction analyses revealed that the combination of higher levels of MVPA with lower levels of SB favourably reshaped the negative relationship between handgrip strength and age (age2 × SB × MVPA: B = -7E-08, SE = 3E-08, P < 0.05). In addition, higher levels of MVPA were independently associated with an improved age-related profile in gait speed (age2 × MVPA: B = 3E-06, SE = 1E-06, P < 0.05), chair-rise performance (age × MVPA: B = -9E-05, SE = 4E-05, P < 0.05) and V̇O2max (MVPA at 21 years: B = 3E-02, SE = 7E-03, P < 0.05; age × MVPA: B = -5E-04, SE = 2E-04, P < 0.05). Conversely, the detrimental association of age with lower-limb muscle strength (age × SB: B = -1E-04, SE = 6E-05, P < 0.05) and chair-rise performance (age × SB: B = 1E-05, SE = 7E-06, P < 0.05) was exacerbated with increasing duration of SB, independently of MVPA. Supplementary analyses further revealed that some of these associations were age and sex specific. CONCLUSIONS: This cross-sectional study demonstrated that reduced sedentary time and increased activity duration were independently and synergistically associated with an attenuated age-related loss in physical capacity. These findings need to be confirmed with longitudinal data but encourage both adopting an active lifestyle and reducing sedentary time as preventive measures against physical aging.

Body composition and aging: cross-sectional results from the INSPIRE study in people 20 to 93 years old.

Aging is characterized by several major changes, including altered body composition, which is associated with numerous negative clinical consequences such as sarcopenia, osteoporosis, and frailty. The study is to evaluate body composition parameters depending on age and sex in a population ranging from the young adult to the very old, and to identify break points in the association between body composition and age. In this cross-sectional study, we included the enrolment population of the French INSPIRE-T prospective cohort, accounting for 915 subjects (62% female). Age ranged from 20 to 93 years, median age (years) was 63 (IQR 27). Body composition (lean mass, fat mass, and bone mineral content) was assessed with dual-X-ray absorptiometry (DXA). Different break points in the relationship between age and body composition variables in males and females were identified using a segmented regression analysis adjusted on physical activity, nutritional status, educational level, and comorbidities. Lean mass decreased from the age of 55 years for males (CI 95% 44-66) and 31 years for females (CI 95% 23-39). For fat mass, we observed a trend towards an increase with age for males. For females, we observed an increase with age up to age 75 (CI 95% 62-86), followed by a decreasing trend. In this study, we described the relationship between body composition and age as a function of sex, establishing a foundation for further studies on predictive biomarkers of age-related body composition alteration.