Substrate oxidation and blood lactate responses to varying exercise intensities in breast cancer patients and healthy controls

Post-treated breast cancer patients were matched with healthy women based on age, physical fitness level and menopausal status. Subjects participated in low, moderate, and high intensity submaximal exercise sessions that corresponded with 40% VO2max, 60% VO2max, and 70% VO2max. Oxygen uptake and respiratory exchange ratio were taken during submaximal exercise sessions to determine substrate oxidation. Blood lactate and blood glucose were measured before and after submaximal exercise sessions. The breast cancer patients had a significantly (p ≤ 0.05) lower carbohydrate oxidation rate and higher fat oxidation rate at all exercise intensities compared to healthy women. The breast cancer patients had a significantly (p ≤ 0.05) lower blood lactate response to exercise at all intensities compared to the healthy women. The results indicate that post-treated breast cancer patients have augmented lipid metabolism and reduced carbohydrate metabolism during submaximal exercise.