ABSTRACT
BACKGROUND: A strategy for maintaining and/or improving cardiorespiratory fitness (CRF) in the growing population of cancer survivors is of major clinical importance, especially in the COVID-19 era. The effect of unsupervised high-intensity interval training (HIIT) on increasing CRF in breast cancer survivors is unknown. PURPOSE: The purpose of this study was to determine whether the newly developed habit-B programme, which involves home-based smartphone-supported HIIT using body weight exercises, improves CRF in early-stage breast cancer survivors. METHODS: This single-centre, 12-week, parallel-group, single-blind, randomised controlled trial involved 50 women with stage I-IIa breast cancer, aged 20-59 years, who had completed initial treatment except for hormone therapy. Participants were randomised to either the exercise or control group. The primary outcome was the 12-week change in peak oxygen uptake [Formula: see text]. Other outcomes included muscle strength, 6 min walk test, resting heart rate, physical activity, fatigue, safety and quality of life. RESULTS: The change in [Formula: see text] and leg strength increased significantly in the exercise group compared with the control group (p<0.01). Changes in other outcomes were not significantly different between the groups. CONCLUSION: A home-based HIIT intervention can lead to improve CRF and muscle strength in early-stage breast cancer survivors.