Effects of high intensity interval training vs moderate intensity continuous training on fitness and body composition in active breast cancer survivors

Abstract

Background: Breast cancer and its treatment are associated with worsened body composition and cardiorespiratory fitness (CRF) in breast cancer survivors. These negative effects can increase overall, cardiovascular and cancer-specific mortality. Exercise as an intervention in cancer populations is increasingly being explored. In recent years there has been the suggestion that high-intensity interval training (HIIT) may be more effective than moderate intensity continuous training (MICT) in the improvement in cardiorespiratory fitness (CRF). Aim: This study compares the addition of HIIT or MICT to a resistance training programme, in recreationally active breast cancer survivors. The aim was to determine which of the two modalities of training was more effective at improving CRF and body composition in physically active breast cancer survivors. Method: Twenty recreationally active breast cancer survivors who had been treated with chemotherapy and/or radiotherapy were recruited from within the EXPINKTTM program at the University of Otago and randomised to complete either HIIT or MICT. Participants completed 2-3 sessions per week for a total of 24 sessions over 9-12 weeks. Each session contained 20 minutes of low-moderate intensity resistance training followed by an aerobic training component. HIIT participants completed sessions of 4 x 4-minute intervals at or above 75% of heart rate reserve (HRR) with 3-minutes active rest between intervals. MICT participants completed a time-matched workout at a continuous 60% HRR. Prior to initiation and following completion participants had a dual X-ray absorptiometry (DXA) scan for body composition and a maximal exercise test with direct measurement of ventilatory gases to determine VO2peak. Results: Nineteen participants completed the intervention with no study-related adverse events. Eighteen of the 19 participants had 100% attendance. Both groups averaged greater than 90% adherence to heart rate protocols. Pre- to post-intervention improvements in VO2peak (p=0.006) and waist circumference (p=0.007) were significant across the groups; however, no statistically significant differences were observed between the groups. In addition, minute ventilation at VO2peak increased in the HIIT, but not the MICT group. Conclusion: This study has demonstrated that the addition of a 12-week intervention of either HIIT or MICT improves CRF and body composition even in already active breast cancer survivors. Further exploration with a larger sample size may be required to determine more broadly whether there is a difference between HIIT and MICT in their effects on CRF and body composition.