The effect of two remote exercise programs on cardiorespiratory fitness, cardiac function, and vascular health in patients with breast cancer

Abstract Breast cancer is a common, survivable malignancy affecting women. With improved survival, the off‐target effects of chemotherapy, such as a decline in cardiorespiratory fitness and worse cardiovascular outcomes, have been recognized. Exercise training may help mitigate these effects. In this study, patients with breast cancer ( N = 24) scheduled to undergo chemotherapy were randomized to either remotely administered high‐intensity interval training (HIIT) or moderate‐intensity exercise (MOD) based on ACSM guidelines for cancer survivors. HIIT involved three weekly sessions using the 4 × 4 protocol at 85%–90% peak heart rate (PHR), while MOD consisted of 150 min per week at 70%–75% PHR. Exercise training began 1–2 weeks before chemotherapy and continued throughout treatment. Baseline testing was conducted prior to chemotherapy and follow‐up testing 7–10 days after completion. Assessments included VO 2peak , echocardiography, vascular function, and blood biomarkers. VO 2peak significantly declined in MOD ( n = 8; 1.50 ± 0.23 to 1.27 ± 0.28 L/min; p = 0.013, d = 1.2), while remaining stable in HIIT ( n = 7; 1.58 ± 0.24 to 1.52 ± 0.28 L/min; p = 0.445, d = 0.3), with a large between‐group effect size ( p = 0.109, d = 0.9). NTproBNP levels significantly increased in MOD (104.3 ± 35.1 to 158.1 ± 56.0; p = 0.018), but not in HIIT. The study was underpowered due to greater than anticipated dropout to detect significant between‐group differences in VO 2peak . These data have implications for the design of scalable exercise interventions in patients undergoing chemotherapy for breast cancer.