Acute cancer-related fatigue response following exercise during an outpatient cancer rehabilitation program.

INTRODUCTION: Cancer-related fatigue (CRF) affects the majority of cancer survivors and can negatively impact activities of daily living. Exercise training reduces CRF, but little is known about the immediate or "acute" association of exercise on CRF. This study examined changes in CRF from before to immediately after and several hours following an exercise session, and explored the relationship of exercise intensity.

METHODS: Observational longitudinal cohort study of cancer survivors enrolled in a 12-week outpatient cancer rehabilitation program. CRF was assessed before, immediately after, and 1-, 4-, and 7-h after one exercise session per week, and at the same clock time on one non-exercise day per week using a visual analog scale (0 = no fatigue, 10 = high fatigue). Exercise sessions consisted of aerobic and resistance training, and intensity was self-selected. Sessions were categorized as either light or moderate based on heart rate and rating of perceived exertion. Mixed effects models with random and fixed effects for time and exercise session intensity evaluated changes in CRF from before to after exercise sessions.

RESULTS: Participants N = 25 (M = 62 ± 12 years, 84% female, 48% Stage III/IV cancer) completed N = 187 exercise sessions (M = 7.0 ± 3.3). There was no change in CRF from before (3.19 ± 1.61) to immediately after exercise sessions (3.13 ± 1.61) (p = 0.62). CRF significantly increased from the post-exercise to the 7-h time point on both exercise (p = 0.001) and non-exercise days (p < .001). There was an increase in CRF (+ .35) following moderate-to-vigorous exercise sessions compared to a decrease following low-intensity sessions (-.21) (p = 0.02).

CONCLUSION: There was no difference in CRF from before to immediately after exercise sessions, and CRF was highest at the 7-h time-point on both exercise and non-exercise days. These findings suggest that exercise had a minimal association with CRF, and exercise intensity was not related to this change in CRF.