Influence of Personalized Exercise Recommendations During Rehabilitation on the Sustainability of Objectively Measured Physical Activity Levels, Fatigue, and Fatigue-Related Biomarkers in Patients With Breast Cancer

Purpose. Only one-third of patients with breast cancer reach the recommended activity level of 15 to 25 MET h/wk. The aim of this study was to determine the influence of personalized exercise recommendations during rehabilitation on patients’ physical activity level, fatigue, and self-perceived cognitive function as well as on side effect–associated biomarkers. Methods. Total metabolic rate, physical activity level, mean MET and steps, fatigue, self-perceived cognitive functioning , and biomarkers (C-reactive protein [CRP], interleukin 6, macrophage migration inhibiting factor [MIF], tumor necrosis factor [TNF]-α, brain-derived neurotrophic factor [BDNF], insulin-like growth factor 1 [IGF1]) were assessed in 60 patients with breast cancer in the aftercare phase before (t(0)) and 8 months after (t(1)) the intervention. The rehabilitation program consisted of an initial 3-week period and a 1-week stay after 4 months. Results. Paired t-test indicated a statistically significant increase in all activity outcomes from t(0) to t(1). Patients’ mean activity level significantly increased from 14.89 to 17.88 MET h/wk. Fatigue and self-perceived cognitive functioning significantly improved from t(0) to t(1). CRP levels significantly decreased, and BDNF as well as IGF1 levels significantly increased over time. Correlation analysis revealed statistically significant negative associations between fatigue, physical activity, and markers of inflammation (TNF-α and MIF). Furthermore, significant positive correlations between subjective cognitive functioning and all dimensions of fatigue were observed. Conclusions. The results support the importance of personalized exercise recommendations to increase physical activity levels in patients with breast cancer. Furthermore, the results highlighti an association between physical activity, fatigue, and inflammation.