Optimal aerobic exercise dose for improving metabolic health and functional outcomes in frail older adults: A systematic review and dose-response meta-analysis.

BACKGROUND AND AIMS: Aerobic exercise potentially mitigates frailty, yet its definitive efficacy and optimal prescription parameters remain unclear. This study aimed to quantify the efficacy and dose-response relationship of aerobic exercise on frailty and health outcomes. METHODS: We conducted a systematic review and dose-response meta-analysis of randomized controlled trials involving adults ≥60 years with frailty or pre-frailty (searched through March 2026). Heterogeneous exercise protocols were standardized to metabolic equivalent (MET)-minutes/week. We employed random-effects models for efficacy, restricted cubic splines to model non-linear dose-response associations, and the GRADE framework to evaluate the certainty of evidence. RESULTS: Forty-four studies (n = 4011) were included. Aerobic exercise significantly improved frailty status (Hedges' g = 0.34), depressive symptoms (Hedges' g = 0.37), muscle strength (Hedges' g = 0.21), cognitive function (Hedges' g = 0.67), quality of life (Hedges' g = 0.57), and lower-limb function (Hedges' g = 0.29 for TUGT; Hedges' g = 0.40 for 30CST) compared with usual care. Subgroup analyses showed consistent efficacy across modalities (e.g., Tai Chi, dance, walking) with no single superior type. CONCLUSIONS: Available evidence suggests that aerobic exercise may improve frailty status and several functional and psychosocial outcomes in frail or pre-frail older adults. The dose-response findings support initiating achievable low-to-moderate volumes of aerobic exercise; however, between-study heterogeneity and sparse data at higher doses preclude firm conclusions regarding an optimal dose. Exercise prescriptions should therefore be individualized according to participants' tolerance, preferences, and clinical status. REGISTRATION: PROSPERO CRD420251152761.