Multi-trajectories of physical activity and health in aging: A 20-year nationwide population-based longitudinal study

Although the beneficial effects of exercise in mitigating adverse health outcomes associated with aging are well-established, the optimal intensity, volume, and frequency of exercise, especially for older adults, remain to be fully elucidated. The aim of this study was to examine the longitudinal association between distinct trajectories of various aspects of physical activity and clinical outcomes (mortality and functional disability (Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) disability) at 4- and 8-year follow-ups among community-dwelling middle-aged and older adults.

In this longitudinal cohort study, we identified 1914 community-dwelling adults from the Taiwan Longitudinal Study on Ageing, TLSA (1996-2015). Using group-based multi-trajectory modeling, we analyzed data from the third (1996) through the sixth (2007) wave of TLSA to identify distinct patterns across four self-reported physical activity aspects (frequency, duration, sweating intensity, and breathlessness intensity) among participants stratified by physical activity documented in the third wave survey (active vs. inactive). Cox proportional hazard models were used to examine the associations between these trajectory patterns and clinical outcomes (mortality, ADL/IADL disability) at 4-year (2011) and 8-year (2015) follow-ups.

Among initially active participants, we identified three trajectories: "Declining Active" (n = 177), "Re-Engaged Active" (n = 200), and "Maintained Active" (n = 622). The "Maintained Active" group showed lower mortality risk at both 4-year (adjusted HR = 0.64, 95 %CI 0.44-0.93) and 8-year (adjusted HR = 0.65, 95 %CI 0.50-0.86) follow-ups compared to the "Declining Active" group. Among initially inactive participants, the "Emerging Active" group (n = 637) demonstrated lower mortality risk compared to the "Chronically Inactive" group (n = 278) at both time points (4-year: adjusted HR = 0.62, 95 %CI 0.43-0.90; 8-year: adjusted HR = 0.68, 95 %CI 0.52-0.89). The "Re-Engaged Active" group showed lower risk of ADL impairment (adjusted HR = 0.44, 95 %CI 0.21-0.87) at 8-year follow-up.

Maintaining active physical activity or transitioning from inactive to active status was associated with reduced mortality risk. These findings support promoting regular physical activity among older adults, regardless of baseline activity levels.