High‐intensity interval training in breast cancer patients: A systematic review and meta‐analysis

BACKGROUND: Women with breast cancer and improved survival often experience treatment‐related impairments. High‐intensity interval training (HIIT) has emerged as a promising exercise therapy modality for adult cancer patients. However, the overall effects of HIIT in breast cancer patients remain scarce and controversial. Therefore, we conducted a systematic review and meta‐analysis to comprehensively evaluate the impact of HIIT on health‐related outcomes in breast cancer patients. METHODS: We searched the PubMed, Embase, and Web of Science from inception to November 7, 2022. Eligible studies included randomized controlled trials that compared HIIT interventions with usual care (UC) or MICT in breast cancer patients. The primary outcome assessed was physical fitness, and exploratory outcomes included body composition, blood‐borne biomarkers, and patient‐reported outcomes. Summary data were extracted, and standardized mean differences (SMD) were calculated for meta‐analysis. For outcomes that could not be pooled, a systematic review was conducted. RESULTS: Our analysis included 19 articles from 10 studies, encompassing 532 participants who met the inclusion criteria. Pooled results demonstrated that HIIT was superior to UC in improving peak oxygen uptake (VO(2peak)). The SMD for VO(2peak) (L/min) and VO(2peak) (mL/kg/min) was 0.79 (95% CI 0.13, 1.45) and 0.59 (95% CI 0.01, 1.16), respectively. No significant differences in VO(2peak) were found between the HIIT and MICT groups. Meta‐analyses on body composition and blood‐borne biomarkers showed no significant differences between HIIT and UC. Systematic review indicated favorable effects of HIIT on muscle strength, fatigue, and emotional well‐being. CONCLUSIONS: HIIT is a time‐efficient alternative to MICT for improving VO(2peak) and may also enhance muscle strength and alleviate fatigue and emotional symptoms in breast cancer patients. HIIT should be considered as an important component of exercise prescription in breast cancer care. Further studies with larger cohorts are needed to determine the clinical significance of HIIT‐induced changes in terms of other outcomes in women with breast cancer.