The Impact of High-Intensity Interval Training Exercise on Breast Cancer Survivors: A Pilot Study to Explore Fitness, Cardiac Regulation and Biomarkers of the Stress Systems

Background: The aim of this study was to explore the impact of exercise intensity on aerobic fitness and autonomic cardiac regulation and salivary biomarkers of the stress systems and mucosal immunity, in breast cancer survivors. Methods: Seventeen participants (62 ± 8 years) were randomly assigned to; 1) high intensity interval training (HIIT; n = 6); 2) moderate-intensity, continuous aerobic training (CMIT; n = 5); or 3) a wait-list control (CON; n = 6) for a 12-week (36 session) stationary cycling intervention. Cardiorespiratory fitness (VO2peak), resting HRV and salivary biomarkers were measured at baseline 2-4 d pre-intervention and 2-4 d post the last exercise session. Key results: High-intensity interval training improved cardiovascular fitness in breast cancer survivors and improved cardiac regulation, and sympathetic nervous system (stress) responses in some individuals. High-intensity interval training was safe and effective for breast cancer survivors to participate in with promising results as a time-efficient intensity to improve physical health and stress.