Effect of Heavy-load Resistance Training During Chemotherapy on Muscle Cellular Outcomes

(Neo-)adjuvant chemotherapy for breast cancer is known to have a negative impact on muscle tissue resulting in reduced aerobic fitness, skeletal muscle mass and strength. Physical exercise during treatment may counteract some of these negative effects. However, the effects of resistance training alone have never been explored. The present study aims to investigate if heavy-load resistance training during (neo-)adjuvant chemotherapy counteracts negative effects on skeletal muscle in women diagnosed with breast cancer. The hypothesis is that (neo-)adjuvant treatment with chemotherapy will reduce muscle fiber size, impair mitochondrial function and increase indicators of cellular stress and that resistance training during treatment will counteract these negative effects. Fifty women recently diagnosed with breast cancer scheduled to start (neo-)adjuvant chemotherapy will be randomized to either an intervention group or a control group. The intervention group will perform supervised heavy-load resistance training twice a week over the course of chemotherapy (approximately 16-weeks) whereas the control group will be encouraged to continue with their usual activities. To increase interest in participation, controls will be invited to a 2-week introduction to the same resistance-training program as the intervention group following completion of chemotherapy. Muscle biopsies from m. vastus lateralis will be collected before the first cycle of chemotherapy, after chemotherapy, and 6 months later (6-month follow-up) for assessment of muscle cellular outcomes. Results from this intervention will provide further knowledge on how chemotherapy affects muscle tissue and how resistance training may counteract immediate and long-term treatment side effects. Results from this intervention will also contribute with knowledge about how to improve exercise programs that are effective for women undergoing chemotherapy against breast cancer.