Cross-sectional and longitudinal associations between physical activity and intrinsic capacity in healthy older adults from the MAPT study

Background: The construct of intrinsic capacity (IC) has been recently developed with the aim of assessing and monitoring life-long individuals' functional trajectories. Physical activity (PA) is recognized for its benefits on health but its associations with IC remain less investigated. We explored the cross-sectional and longitudinal associations of PA with IC in non-demented older adults.

Methods: Eight hundred and thirty-seven males and females aged 70 years and over, were included in the present work. IC and its domains (mobility, vitality, cognition, psychology and sensory) were assessed over 2 years and converted to a 0-100 scale. Participants were categorized into 5 PA groups (0-29; 30-499; 500-999; 1000-1999; and 2000+ MET-min/week) using questionnaires. The associations between PA and IC variables (all reflected and square-root-transformed) observed over 2 years were examined using mixed-effect linear regressions.

Findings: Over the 2-year follow-up, ordinal PA was associated with higher scores in IC (B = -0.066, SE = 0.015, p < .001) In addition, compared to the inactive group, most of the active groups had a slower decline in IC (B_{30-499 MET-min/week} = -0.196, SE = 0.078; B_{500-999 MET-min/week} = -0.208, SE = 0.076; B_{1000-1999 MET-min/week} = -0.165, SE = 0.073; B_{2000+MET-min/week} = -0.187, SE = 0.074; all p < .05). Subdomain analyses revealed that these associations were driven by mobility, vitality and psychological domain.

Interpretation: This study suggests that PA may help preventing IC decline, especially mobility, vitality, and psychology in older adults.