Unravelling the miscellaneous effects of exercise interventions on activities of daily living in frail older adults: A systematic review and meta-analysis

INTRODUCTION: Frailty in older adults impairs Activities of Daily Living (ADL). While exercise interventions improve factors like muscle strength and physical function, their direct impact on ADL ability is inconsistent. This review aims to assess the effectiveness of exercise on ADL ability, identify the most beneficial interventions, and explore mediators. METHOD: A systematic search in five databases included randomized controlled trials (RCTs) on frail adults (60 +) comparing exercise interventions to usual care, with ADL ability as an outcome. Methodological quality was assessed using the Cochrane risk of bias (ROB) tool. Meta-analyses were performed using random effects models, with heterogeneity assessed by the I² index. Subgroup analyses were conducted based on therapeutic validity (intervention according to exercise recommendations), adherence, cumulative therapeutic validity and adherence, ADL-measurement tool and ROB. Mediators were categorized based on study findings. RESULTS: Of 5975 records, 24 papers (20 RCTs) met criteria. Two had high ROB. Exercise improved ADL ability (Standardised mean difference = 0.59) but heterogeneity was high (I² = 83 %), partly explained by measurement tool and ROB. High therapeutic validity was associated with lower adherence rates, but interventions showing high therapeutic validity and/or adherence did not show larger ADL performance improvements. Potential mediators include physical function, cognition, balance confidence, quality of life, psychosocial factors, strength and self-perceived health/pain. CONCLUSION: Exercise improves ADL performance, but high heterogeneity in results limits generalizability. Effective interventions should integrate physical, cognitive, and psychosocial components while ensuring gradual progression to balance therapeutic validity with adherence. Future research should use mediation analyses to clarify underlying mechanisms.