Effects of exercise training on frailty, cardiorespiratory fitness, and lower limb function in non-dialysis chronic kidney disease: a systematic review and meta-analysis

INTRODUCTION: Physical frailty, impaired cardiorespiratory fitness (CRF), and diminished lower limb function are prevalent in non-dialysis chronic kidney disease (NDD-CKD) and strongly associated with adverse clinical outcomes. This systematic review and meta-analysis aimed to evaluate the efficacy of exercise training interventions on the core dimensions of the frailty phenotype, CRF, and lower limb function in the NDD-CKD population. METHODS: Seven electronic databases were systematically searched from inception to March 1, 2026, for randomized controlled trials (RCTs) comparing structured exercise interventions with usual care or sham exercise in adult NDD-CKD patients. Primary outcomes included the five core frailty phenotypes (absolute body weight, handgrip strength, walking speed, physical activity, and fatigue), CRF, and lower limb function. Data were synthesized using a random-effects model, reporting standardized mean differences (SMDs) with 95% confidence intervals (CIs). This study is registered with PROSPERO (CRD420261363651). RESULTS: Eighteen RCTs encompassing 938 participants were included. Compared with the control group, exercise interventions significantly improved specific frailty dimensions, notably increasing walking speed (SMD = 0.36, 95% CI 0.03-0.69; P = 0.03) and alleviating fatigue (SMD = 0.34, 95% CI 0.04-0.64; P = 0.03). Furthermore, exercise significantly enhanced overall CRF (SMD = 0.46, 95% CI 0.29-0.63; P < 0.001) and lower limb function (SMD = 0.55, 95% CI 0.32-0.79; P < 0.001). Outcomes for absolute body weight, handgrip strength, and general physical activity levels did not reach statistical significance. CONCLUSION: Exercise training is an effective and safe intervention method that can alleviate specific frailty characteristics (walking speed and fatigue), and enhance the cardiovascular and lower extremity functions of NDD-CKD patients. It is advocated to promote exercise as an early "pre-rehabilitation" strategy to enhance the physical functional reserve of patients before dialysis. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/, identifier CRD420261363651.