High-intensity Vs. Moderate-intensity Exercise On Ventilatory Efficiency And Oxygen Uptake In Patients With Breast Cancer

Ventilatory efficiency and oxygen uptake efficiency slopes (OUES) predict morbidity and mortality independent of VO2peak. However, it is unknown if exercise has the same effects in patients with breast cancer (BC) receiving chemotherapy and the role of exercise intensity is unclear. PURPOSE: This secondary analysis examined if high-intensity interval training (HIIT) was more effective than moderate-intensity exercise training (MOD) for the preservation of ventilatory efficiency and OUES following chemotherapy in females with BC. METHODS: Twenty-four patients with BC scheduled for chemotherapy were randomized to 1 of 2 interventions 1) MOD: 150 min/week of walking at 70-75% peak heart rate (PHR) or 2) HIIT: 3 sessions/week of 4x4 intervals at 85-95% PHR on a recumbent bicycle. Subjects underwent V̇O2peak testing on a recumbent bicycle using a 15 watt/min ramp protocol to obtain breath-by-breath data and PHRs for exercise prescription. Post-testing occurred within 3-10 days after the final treatment. Individual deltas for VE/VO2, VE/VCO2, and OUES slopes from between-group differences were analyzed via independent samples t-tests after assessing for normality. Alpha was a priori set at 0.05. RESULTS: Thirteen subjects completed all aspects of the study (MOD: n = 6, 54.2 ± 10.3 yrs, 65.6 ± 7.4 kg, 25.1 ± 4.3 kg/m2; HIIT: n = 7, 55.3 ± 11.9 yrs, 78.7 ± 15 kg, 28.9 ± 5.5 kg/m2). There were no significant differences between MOD or HIIT for changes in overall VE/VO2 slope (9.88 ± 12.87 vs. 2.32 ± 9.75; p = 0.25, d = 0.67), overall VE/VCO2 slope (2.83 ± 4.66 vs. 2.42 ± 3.54; p = 0.86, d = 0.10), OUES (-0.34 ± 0.14 vs. -0.16 ± 0.25; p = 0.14, d = 0.88), VE/VO2 slope pre- or post-VT, VE/VCO2 slope pre- or post-VT from baseline values (p > 0.05). CONCLUSION: VE/VO2 slopes and OUES were worse in the MOD following BC chemotherapy vs. HIIT. Large effect sizes (d > 0.7) were observed; however, the present study was underpowered and needs to be replicated in a larger sample of patients. Supported by: UVA CPH & iPRIME Seed Funding