Grant: Travel Awards - Institute Community Support

While the benefits of exercise during chemotherapy for breast cancer are well established, the optimal exercise prescription during chemotherapy remains undetermined. The majority of exercise-oncology research prescribes exercise that linearly increases in intensity and duration. However, chemotherapy received multiple times in 2-3 week cycles results in fluctuations and accumulations in side-effects, such as fatigue. Thus, linear exercise prescriptions fail to account for patient-reported and physiological changes during chemotherapy, which may reduce exercise adherence. Our aim was to evaluate adherence to a "chemotherapy-periodized" exercise prescription, as well as changes in fatigue during chemotherapy to provide a rationale for the use of this exercise prescription. Women with breast cancer were randomized to supervised exercise or usual care during chemotherapy (4 cycles every 2-3wks). The exercise program progressed in duration and intensity. However, for one week following each chemotherapy cycle (chemotherapy-week), exercise intensity was reduced to account for anticipated increases in treatment side-effects. Fatigue was evaluated at baseline and at the end of chemotherapy, and across a chemotherapy cycle to detect a cyclical variation. We observed equivalent attendance and adherence to exercise duration and intensity for chemotherapy and non-chemotherapy weeks. There was no difference in fatigue between women who exercised versus received usual care, so fatigue was evaluated over time among all participants. We detected a cyclical pattern in fatigue over a chemotherapy cycle, where fatigue peaked 3-5 days following chemotherapy and then recovered, but not to baseline levels prior to the next cycle. This peak in fatigue was concurrent to our prescribed reduction in exercise intensity. Overall, "chemotherapy-periodized" exercise may optimize exercise adherence among women with breast cancer by accommodating for variations in treatment side-effects.