Impact of community-based exercise on fatigue in early breast cancer survivors: identifying potential determinants of change.

Abstract

Exercise has been shown to reduce fatigue in early breast cancer survivors (EBCS), though it is unclear if these results translate to community-based exercise settings. Mechanisms that influence changes in fatigue seen after exercise are also poorly understood. This study sought to evaluate the impact of community-based exercise and identify associations of fatigue in EBCS. Twenty-nine EBCS and 13 non-cancer controls (CON) enrolled. Pre/post-intervention measurements included measures of fitness/function, balance, and adherence/compliance as well as self-reported measures of fatigue, health-related quality of life (HRQOL), well-being, self-efficacy, and physical activity. Both groups participated in a supervised 16-week aerobic + resistance exercise intervention. A mixed model ANOVA and Cohen's D effect size assessed fatigue changes, and univariable linear regressions identified fatigue associations. Fatigue improved for EBCS (- 2.6, Cohen's D = 0.51) but not CON (0.0, Cohen's D = 0.02); no interaction effect was observed. Post-intervention fatigue in EBCS was associated with better QOL (R2 = 0.387; p < 0.01), depression (R2 = 0.251; p < 0.01), self-efficacy, (R2 = 0.453; p < 0.01), outcome expectations from exercise (R2 = 0.254; p < 0.01), balance (R2 = 0.167; p < 0.05), and the6-minute walk test (R2 = 0.193; p < 0.05). EBCS improvements in fatigue were associated with improvements in self-reported physical health (R2 = 0.425; p < 0.01), depression (R2 = 0.233; p < 0.01), pain (R2 = 0.157; p < 0.05), outcome expectations from exercise (R2 = 0.420; p < 0.01), and the6-minute walk test (R2 = 0.172; p < 0.05). Less fatigue in the CON group was shown be associated with better sleep quality (R2 = 0.309; p < 0.05) and pain (R2 = 0.259; p < 0.05). Community-based exercise appears beneficial for alleviating fatigue in EBCS. These improvements may be driven by parallel improvements in psychosocial outcomes and objectively measured functional outcomes.