'Chemotherapy-periodized' Exercise to Accommodate for Cyclical Variation in Fatigue

PURPOSE The purpose of this study was to provide a rationale for "chemotherapy-periodized" exercise by characterizing cyclical variations in fatigue and exercise response across a chemotherapy cycle and comparing exercise adherence during chemotherapy between a prescription that is periodized according to chemotherapy cycle length and a standard linearly progressed prescription. METHODS Women with breast cancer who were prescribed taxane-based chemotherapy were randomly assigned to a supervised aerobic and resistance exercise program after a chemotherapy-periodized exercise prescription (n = 12) or to usual care during chemotherapy (n = 15). Fatigue and steady state exercise responses were assessed in both groups before the first taxane treatment and across the third treatment (i.e., 0-3 d prior and 3-5 d after the third treatment, and 0-3 d before the fourth treatment) to assess cyclical variations. Adherence to the chemotherapy-periodized exercise prescription was compared with adherence to a standard linear prescription from a prior study in a similar population (n = 51). RESULTS Fatigue increased from baseline (marginal mean ± standard error: 3.2 ± 0.4) to before the third treatment (4.1 ± 0.4, P = 0.025), then peaked at 3 to 5 d after the third treatment (5.1 ± 0.4, P = 0.001), before recovering before the fourth treatment (4.3 ± 0.5, P = 0.021). The peak in fatigue at 3 to 5 d post-third treatment corresponded to a decrease in steady state exercise oxygen consumption (V˙O2) (P = 0.013). Compared with a standard linear exercise prescription during chemotherapy, a chemotherapy-periodized exercise prescription resulted in higher attendance during the week after chemotherapy (57% ± 30% vs 77% ± 28%, P = 0.04) and overall attendance (63% + 25% vs 78% ± 23%, P = 0.05). CONCLUSIONS Fatigue and exercise V˙O2 vary across a chemotherapy cycle. A chemotherapy-periodized exercise prescription that accommodates cyclical variations in fatigue may increase adherence to supervised exercise.