Abstract
BACKGROUND: Cancer-related fatigue (CRF) is a debilitating side effect among patients with cancer. While exercise is recommended to manage CRF, clinical guidelines lack specificity on modality, intensity, and duration. This study aimed to determine the optimal doses of walking to mitigate CRF. METHODS: In a nationwide, prospective cohort study of patients with stage I-IIIC breast cancer, we assessed walking volume (MET-hours/week) via Aerobics Center Longitudinal Study Physical Activity measure and CRF via Multidimensional Fatigue Symptom Inventory (MFSI) at pre-chemotherapy (T1), one month post-chemotherapy (T2), and six months post-chemotherapy (T3). A receiver operating characteristic curve analysis identified a cut-point for walking volume needed for a clinically meaningful CRF reduction from T1 to T2 (-4.5 points MFSI score). Linear mixed models controlling for age, BMI, and other modes of moderate-vigorous intensity exercise characterized CRF at each time point. RESULTS: Among 577 participants (mean age 53.4 years; 76% stage I/II) higher walking volume was associated with lower general, emotional, physical, overall CRF and higher vigor post-chemotherapy (T2; all p < .05). Those who walked ≥4.3 MET-hours/week, equivalent to walking 88-172 minutes at a low-intensity pace (<2.5 mph) or 43-83 minutes at a moderate-intensity pace (2.6-4.5 mph) at pre-, during, and post-chemotherapy demonstrated significantly lower CRF at post-chemotherapy (T2) compared to those who walked <4.3 MET-hours/week (p < .05). CONCLUSIONS: Our data indicate that higher walking volume was associated with lower CRF and a minimum walking volume of 88-172 minutes at a low-intensity pace or 43-83 minutes of moderate-intensity pace, may attenuate CRF following chemotherapy.