Individual variability and predictors of responsiveness in physical outcomes following multicomponent physical training in older adults

Abstract Purpose Contributing factors to individual variability in responses to physical training among older adults remain poorly understood. We investigated variability in changes in strength, lean mass, and walking outcomes following a 12-month physical training, and health-related factors associated with high responses. Methods Community-dwelling older adults ( n = 314; mean age 74.5 ± 3.8 years) were randomized to physical or combined physical and cognitive training. Physical training included resistance, walking, balance, and flexibility training. Cognitive training consisted of executive function tasks. Participants were classified as high or low responders in each outcome according to whether their change scores exceeded the smallest worthwhile change (0.2 × standard deviation at baseline). A total of 288 participants attending baseline and post-intervention measurements were included in the responder analyses regardless of group allocation. Results Grip strength, knee extension strength, walking speed, and walking distance improved significantly (all p < 0.01) with 27%, 46%, 30%, and 44% of participants classified as high responders, respectively. No significant change was observed in appendicular lean mass, although 17% were classified as high responders. Overall, 46% were categorized as having a high response in 2–5 outcomes. Multimorbidity (OR 2.60, 95% CI 1.47–4.59) younger age (OR 0.90, 95% CI 0.84–0.96), lower body mass index (OR 0.94, 95% CI 0.88–0.99), and higher resistance training adherence (OR 1.03, 95% CI 1.01–1.04) were associated with having 2–5 high responses. Conclusion These findings suggest that multimorbidity, younger age, lower body mass index, and higher resistance training adherence are associated with greater responsiveness across multiple physical outcomes.