ACUTE EFFECTS OF EXERCISE INTENSITY ON FATIGUE DURING A CANCER-REHABILITATION PROGRAM

PURPOSE: Cancer related fatigue (CRF) is a common and distressing side effect of cancer treatment(s). Outpatient cancer rehabilitation programs that include weekly exercise sessions can reduce CRF. However, the immediate or “acute” effect of exercise sessions on CRF is unclear. This study compared CRF from immediately before and after exercise sessions completed as part of an outpatient cancer rehabilitation program and explored the impact of self-selected exercise intensity on change in CRF. METHODS: Observational, longitudinal cohort study of participants enrolled in a 12-week outpatient cancer rehabilitation program. CRF was assessed using a visual analog scale (0=no fatigue–10=worst fatigue) before and immediately after one exercise session every week. Exercise intensity was self-selected and tracked using heart rate monitors and rating of perceived exertion (RPE). Each session was classified as light (heart rate reserve (HRR 30-39% and RPE 9-11) or moderate/vigorous (HRR 40-89% and RPE 12-20). A mixed-effects model accounting for within (time) and between (exercise intensity) effects was used to examine change in CRF from pre-to-post exercise session. RESULTS: Participants (N=18) were M= 64 years old, 77% female, and diagnosed with breast (n=4) lymphoma (n=2), lung (n=2) or other (n=10) cancer. Measures of pre/post CRF were completed in 156 exercise sessions, 53% (n=83) were classified light and 47% (n=73) as moderate/vigorous intensity. Average pre-exercise CRF, HRR and RPE for each intensity category was light (3, 30% and 11) and moderate/vigorous (2.8, 47% and 12). Average change in CRF from pre- to post-exercise was MΔ= 0.10±2.2 overall, MΔ= -0.15±.22 for light intensity, and MΔ= .29±.24 for moderate/vigorous intensity sessions. There was no effect of time (β = 0.037, p = 0.82), or intensity (β = 0.48, p = 0.13). CONCLUSION: There was no change in CRF from immediately before to after exercise sessions, and no effect of self-selected exercise intensity. Further research should explore potential study limitations, including sensitivity of CRF measurement tool, and the potential ceiling effects due to the low pre-exercise CRF.