Effects of aerobic exercise during chemotherapy on cancer-related fatigue and health-related quality of life in patients with breast cancer: a systematic review and meta-analysis

Cancer-related fatigue (CRF) and impaired health-related quality of life (HRQoL) are prevalent and clinically important concerns in patients with breast cancer undergoing chemotherapy. Although exercise is recommended during cancer treatment, the magnitude and certainty of the effects attributable specifically to aerobic exercise delivered during chemotherapy remain unclear, as does potential variation across exercise-program characteristics. This review aimed to quantify the effects of aerobic exercise on CRF and HRQoL in this setting and to explore potential variation across exercise-program characteristics. A comprehensive search was conducted across PubMed, Embase, Web of Science, the Cochrane Library, and EBSCOhost from inception to February 2026. Randomized controlled trials of aerobic exercise during chemotherapy in adult patients with breast cancer were included. A meta-analysis was conducted to quantify standardized mean differences (SMDs) and 95% confidence intervals (CIs). Risk of bias, sensitivity analyses, publication bias, prespecified subgroup analyses, and GRADE certainty of evidence were assessed. A total of 11 randomized controlled trials involving 933 participants met the inclusion criteria. Aerobic exercise significantly reduced CRF compared with usual care or nonexercise control conditions (SMD, -0.38; 95% CI, -0.63 to -0.12; p = 0.004) and improved HRQoL (SMD, 0.52; 95% CI, 0.28 to 0.75; p < 0.001). Subgroup analyses suggested potentially greater effects with moderate-to-high intensity exercise, continuous or composite aerobic exercise, and partially supervised interventions; however, between-group differences were not statistically significant. Aerobic exercise during chemotherapy was associated with reduced CRF and improved HRQoL in patients with breast cancer. These findings support considering individualized aerobic exercise as an adjunct to supportive oncology care; however, residual heterogeneity and nonsignificant between-subgroup differences preclude identification of an optimal program. Future trials should directly compare exercise-program characteristics and consistently report adherence, achieved exercise dose, safety, and chemotherapy-related outcomes. PROSPERO CRD420261294637.