Supervised structured exercise improves cardiorespiratory fitness in adults with MASLD by 3.52 mL/kg/minSupervised Exercise Improves Heart Fitness in MASLD Patients

Cardiorespiratory fitness (CRF), primarily assessed via maximal oxygen uptake (VO₂max) or peak oxygen uptake (VO₂peak) during incremental exercise testing, is a robust predictor of cardiovascular mortality in individuals with metabolic dysfunction-associated steatotic liver disease (MASLD). However, the exercise volume associated with greater CRF gains in this population remains poorly defined. Therefore, this study aimed to evaluate the efficacy of supervised structured exercise on CRF in MASLD individuals and characterize the dose-response relationship using restricted cubic splines. We systematically searched PubMed, Embase, and Web of Science through July 18, 2025, for randomized controlled trials comparing supervised exercise with usual care in adults with MASLD. The primary outcome was CRF, measured as VO2peak/VO2max. Standardized mean differences (SMDs) were pooled using random-effects models. Dose-response analysis was conducted via a Bayesian framework using restricted cubic spline model to identify optimal weekly and cumulative exercise volumes. Thirteen RCTs comprising 15 exercise-control comparisons involving 356 participants were included. Exercise significantly improved CRF compared with control conditions (SMD = 0.82, 95% CI: 0.54–1.10; I2 = 30.1%). In the MD-based analysis restricted to studies reporting CRF in mL/kg/min, exercise increased CRF by 3.52 mL/kg/min (95% CI: 2.04–5.01; I2 = 65.5%). Exploratory dose-response analyses suggested non-linear associations, with estimated peak points of approximately 590 MET-min/week for weekly exercise volume and 10,715 MET-min for total cumulative exercise volume. Exercise interventions improve CRF in individuals with MASLD. Exploratory dose-response analyses suggest that CRF gains may follow a non-linear pattern with increasing exercise volume, but the estimated peak points should be interpreted as model-based indicators rather than definitive prescription thresholds. https://www.crd.york.ac.uk/PROSPERO/view/CRD420251243283, PROSPERO CRD420251243283.