Effects of exercise interventions during different treatments in breast cancer

Previous findings suggest that exercise is a safe and efficacious means of improving physiological and psychosocial outcomes in female breast cancer survivors. To date, most research has focused on post-treatment interventions. However, given that the type and severity of treatment-related adverse effects may be dependent on the type of treatment, and that the effects are substantially more pronounced during treatment, an assessment of the safety and efficacy of exercise during treatment is warranted. In this review, we present and evaluate the results of randomized controlled trials (RCTs) conducted during breast cancer treatment. We conducted literature searches to identify studies examining exercise interventions in breast cancer patients who were undergoing chemotherapy or radiation. Data were extracted on physiological and psychosocial outcomes. Cohen's d effect sizes were calculated for each outcome. A total of 17 studies involving 1,175 participants undergoing active cancer therapy met the inclusion criteria. Findings revealed that, on average, exercise interventions resulted in moderate to large improvements in muscular strength: resistance exercise (RE, 𝑑 = 0.86), aerobic exercise (AE, 𝑑 = 0.55), small to moderate improvements in cardiovascular functioning (RE, 𝑑 = 0.45; AE, 𝑑 = 0.17, combination exercise (COMB, 𝑑 = 0.31) and quality of life (QoL; RE, 𝑑 = 0.30; AE, 𝑑 = 0.50; COMB, 𝑑 = 0.63). The results of this review suggest that exercise is a safe, feasible, and efficacious intervention in breast cancer patients who are undergoing different types of treatment. Additional research addressing the different modes of exercise during each type of treatment is warranted to assess the comparable efficacy of the various exercise modes during established breast cancer treatments.