Physical Activity Contributes To Fatigue In Cancer Survivors With A Sedentary Lifestyle

Fatigue in cancer survivorship is a significant problem, affecting approximately 30% of survivors. Physical exercise is one of few known treatments for fatigue, but evidence of its efficacy is largely based on those willing and able to engage in exercise studies. As fatigue is a barrier to engage in exercise, more insight is needed in the association between physical activity and fatigue. PURPOSE: To explore associations between daily physical activity (PA) and fatigue in fatigued cancer survivors with an active vs. relatively sedentary lifestyle. METHODS: Cancer survivors post treatment with no evidence of disease or stable disease, heterogeneous for cancer diagnosis and treatment history, completed seven days of ambulatory testing for PA (actigraph-based) and momentary fatigue (self-reported at the end of the day on a 0-10 scale). Participants with at least four days of ≥10 hours recorded actigraph data were included in analyses. Daily average steps/minute and vector magnitude count/minute (VM; a tri-axial composite score of PA) were computed as PA predictors of fatigue; a median-split on minutes/day in moderate to vigorous activity (MVPA) identified participants with relatively active (≥27.5 minutes/day) or sedentary lifestyles. Associations of PA with fatigue were assessed by linear mixed models including sex, age, and BMI as covariates, and interactions between the PA outcomes and median-split MVPA as predictors of fatigue. RESULTS: Available data included 226 observation days from 34 participants (mean age = 56.47 years [range: 32-80], >80% non-Hispanic White, 68% female, most common cancer diagnoses: Breast [35%], hematological [21%], and genitourinary [12%]). Both steps/minute and VM/minute showed a significant interaction with MVPA in predicting end-of-day fatigue (β = 0.209, p = 0.030 and β =0.003, p = 0.039, respectively). Higher PA was associated with greater fatigue in participants with a sedentary lifestyle, but not in those with a more active lifestyle. CONCLUSIONS: These preliminary results suggest that cancer survivors with a relatively sedentary lifestyle may experience increased fatigue after increases in physical activity. This could serve as a barrier to engaging in more physical activity, thus preventing the adoption of an active lifestyle that could alleviate fatigue long-term. University Cancer Foundation via the Institutional Research Grant program at the University of Texas MD Anderson Cancer Center