Effects of high‑intensity interval training on physical function and quality of life in breast cancer patients: a systematic review and meta-analysis

BACKGROUND: Breast cancer remains the most common malignancy among women worldwide. Despite advances in screening and treatment that have improved five-year survival, patients often experience weight gain, reduced cardiorespiratory fitness, metabolic disturbances, and impaired quality of life during or after therapy. Moderate‑intensity continuous training (MICT) is effective but time‑consuming, while high‑intensity interval training (HIIT) offers a time‑efficient alternative that may provide greater cardiopulmonary stimulation. However, evidence on its effects on body composition, quality of life, and inflammatory markers in breast cancer patients remains inconclusive. METHODS: A comprehensive search of PubMed, Embase, Web of Science, the Cochrane Library, CNKI, Wanfang and VIP databases was conducted up to July 31, 2025 to identify randomized controlled trials (RCTs) comparing HIIT with MICT or usual care (UC) in women aged ≥ 18 years diagnosed with breast cancer. Eligible interventions involved HIIT, while control groups received MICT or UC. The primary outcome was peak oxygen uptake (VO₂peak), reflecting cardiorespiratory fitness, and quality of life, whereas secondary outcomes included body composition, and the inflammatory marker interleukin‑6(IL‑6). Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated, and fixed or random‑effects models were applied according to heterogeneity levels. RESULTS: A total of ten randomized controlled trials (providing 13 comparison arms) involving 330 participants were analyzed. Compared with control interventions, HIIT significantly increased VO₂peak (SMD = 0.74; 95% CI [0.47,1.01]; I²=9.2%), with further subgroup analysis showing a significant improvement versus UC (SMD = 0.85; 95% CI [0.54,1.15]) but no significant difference compared with MICT (SMD = 0.38; 95% CI [-0.18,0.94]). No significant changes were found in BMI (SMD=-0.16; 95% CI [-0.45,0.13]), fat mass (SMD=-0.23; 95% CI [-0.51,0.06]), lean body mass (SMD = 0.22; 95% CI [-0.06,0.51]) or body fat percentage (SMD=-0.32; 95% CI [-0.88,0.24]). Regarding quality of life, functional well‑being (SMD = 0.89; 95% CI [0.39,1.39]) and social well‑being (SMD = 0.79; 95% CI [0.29,1.28]) improved significantly, whereas emotional well‑being improved only when HIIT was compared with UC (SMD = 0.65; 95% CI [0.08,1.23]). Physical well‑being did not differ significantly (SMD = 0.24; 95% CI [-0.24,0.71]). HIIT did not significantly reduce IL‑6 levels (SMD=-0.22; 95% CI [-0.65,0.22]). CONCLUSIONS: HIIT appears to be safe and significantly improved cardiorespiratory fitness (VO₂peak) compared with usual care but showed no significant effects on body composition or IL-6 levels. Benefits in some quality-of-life domains were observed but based on limited evidence. HIIT did not outperform moderate-intensity continuous training.