The Effect Of Aerobic Exercise During Chemotherapy On Fitness In Individuals With Non-Metastatic Breast Cancer

Aerobic exercise and CogniTIVe functioning in women with breAsT cancEr (ACTIVATE) was a 2-arm, single-blinded randomized controlled trial examining the effects of supervised, progressive aerobic exercise on cognitive function in individuals receiving curative-intent chemotherapy for breast cancer. Participants were randomized to exercise during chemotherapy (EX) or usual care wait-list control (UC). EX was periodized to participants’ chemotherapy regimen and lasted 12 to 24 weeks based on chemotherapy duration. PURPOSE: To test differences in aerobic fitness between EX and UC at baseline and after chemotherapy. METHODS: Ventilatory threshold (VT) and relative VO2peak were measured using a maximal cardiopulmonary exercise test (CPET) on a cycle ergometer at baseline and after chemotherapy. Maximal heart rate (end of CPET) and wattage (maintained for ≥30s in last stage of CPET) were also assessed. T-tests were used to evaluate between-group differences in VT, relative VO2peak, time to VT and VO2peak, maximal heart rate, and maximal wattage from baseline to after chemotherapy. RESULTS: The analytical sample comprised 31 participants (EX: n = 19; UC: n = 12) with a mean age of 49.1 ± 11.1 years. Most participants (77%) received adjuvant chemotherapy. At baseline, there were no significant differences in aerobic fitness outcomes between groups (p < 0.05). From baseline to after chemotherapy, UC and EX exhibited a decrease in VT (-0.24 ± 0.47 vs. -0.06 ± 0.33 L/min; p = 0.22), VO2peak (-3.6 ± 3.6 vs. -1.4 ± 4.1 L/min; p = 0.13), maximal heart rate (-2.7 ± 7.4 vs. -3.5 ± 8.2 bpm; p = 0.39), and time to VT (-90.5 ± 123.5 vs. -28.1 ± 152.1 s; p = 0.12); none of these changes significantly differed between groups. Compared to EX, UC had a significantly greater decrease in maximal wattage (-30.2 ± 22.3 vs. -11.1 ± 28.6 W; p = 0.047) and time to VO2peak (-115.3 ± 56.7 vs. -63.1 ± 99.4 s; p = 0.036) from baseline to after chemotherapy. CONCLUSIONS: While both UC and EX experienced declines in aerobic fitness outcomes after chemotherapy, the magnitude of decrease in maximal wattage and time to VO2peak was significantly greater for UC participants, who did not exercise during chemotherapy. Additional work is needed to explore differences in aerobic fitness outcomes by participant subgroup (e.g., age, chemotherapy type). Canadian Cancer Society Research Institute, AVON Foundation