UBC Theses and Dissertations
High-intensity exercise and safety concerns in breast cancer survivors Dolan, Lianne Bronagh
Prescribing exercise as an adjuvant therapy for cancer survivors is becoming an acknowledged rehabilitative tool to offset the numerous biological toxicities that can develop with cancer treatments. Exercise interventions for breast cancer survivors typically prescribe low-to- moderate intensities to counteract the treatment-induced dysfunctions. These prescriptions have elicited inconsistent results. Interval training is currently being explored in many clinical populations with positive outcomes; however, the use of higher intensity exercise in the cancer population is not yet encouraged. Through four different studies, this doctoral dissertation investigated the safety of implementing higher intensity exercise protocols into breast cancer survivor rehabilitative programs during chemotherapy (N=60) and post-primary therapy (N=33). The influence of intensity on safety, aerobic capacity and anaerobic capacity was explored. Supervised exercise programs and maximal aerobic stress tests were administered on a treadmill as it was demonstrated to be the preferred mode of exercise; in spite of this, the measure of anaerobic capacity was determined to be the most reliable on a cycle ergometer. Safety issues concerning neutropenia, altered chemotherapy dose, and biomarkers associated with poor outcome, were investigated. During chemotherapy (FEC-D), 30 early-stage breast cancer patients exercised at intensities between 70- 90% V02peak, thrice weekly, for the duration of their treatment (18.5 weeks). Women were able to safely incorporate bouts of higher intensity exercise without increased hospitalization, immunosuppression, or negatively impacting their chemotherapy dose (achieved RDI was 92%, achieved RDI in the matched, usual care group was 90%). Post-primary therapy, 33 postmenopausal breast cancer survivors were randomized into 3 groups (supervised high-intensity interval training (HIT), supervised continuous moderate-intensity exercise training (CMT) and an unsupervised control group). For 6 weeks, women in the HIT group exercised at intensities between 70 to 100% V0₂peak, while the CMT group exercised between 60-70% V0₂peak. HIT and CMT led to significant improvements in health-associated outcomes, however the mechanisms that led to these benefits may have differed between the groups. No adverse events occurred due to high-intensity exercise in either supervised intervention. This dissertation provides evidence that breast cancer survivors can incorporate bouts of higher intensity exercise into their supervised rehabilitation programs during, or post-primary therapy.
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