Brown, J. C., Huedo-Medina, T. B., Pescatello, L. S., Pescatello, S. M., Ferrer, R. A., & Johnson, B. T. (2011). Efficacy of exercise interventions in modulating cancer-related fatigue among adult cancer survivors: a meta-analysis. Cancer Epidemiology, Biomarkers & Prevention, 20, 123–133.

To evaluate the effect of types of exercise on cancer-related fatigue.

Only randomized, controlled trials studying the outcome variable of cancer-related fatigue were included.

Seven thousand two hundred forty-five articles met the initial selection criteria. A final sample of 44 studies was included. Two independent raters collected data, and the intensity of exercise was estimated using metabolic equivalent units (METs).  MET values for a given exercise were coded from the Compendium of Physical Activity.

• The total number of participants across all studies was 3,245.
• Twenty-five studies exclusively reported breast cancer survivors.
• Mean age was 53.8 years.
• Forty-six percent of patients were undergoing active cancer treatment.

Characteristics of the Interventions

• Average length of exercise was 11.5 weeks (standard deviation [SD] = 5.2 weeks), and average intensity was 5.6 MET.
• Twenty-four studies included only aerobic exercise, six included only resistance exercise, 11 included a combination of resistance and aerobics, and six used neuromuscular exercise, such as yoga or tai chi.
• Ten studies used a theoretical base:  transtheoretical model of behavior change, self-efficacy, Roy adaptation model, Payne adaptation model, and the Levine conservation model.

Fatigue Measurement

• Fatigue was measured in 30% of patients with the Functional Assessment of Cancer Therapy (FACT) questionnaire, 20% with the Piper Fatigue Scale, 13% with the Profile of Mood States (POMS), 11% with the Brief Fatigue Inventory (BFI), 11% with the European Organisation for Research and Treatment of Cancer Quality of Life questionnaire (EORTC QOL-C30), and 4% with the linear analog scale.

Regression analysis was used to identify factors that were related to the degree of fatigue modulation.  Significant factors were

• Adherence to a theoretical model (p < 0.001)
• Sample of older cancer survivors (p = 0.04)
• Moderate intensity resistance exercise use (3–6 MET) (p = 0.01).

Session length and number of exercise sessions were not significantly related to effects on fatigue.

Overall effect size of fatigue modulation was 0.31 (95% confidence interval [0.22, 0.4]).  Effect size was 0.39 among survivors of breast cancer and 0.42 among survivors of prostate cancer.  In other cancer types, there were few studies and very small effects, but analysis demonstrated a consistent effect in favor of exercise.

Resistance exercise of moderate intensity appears to be the most effective in reducing cancer-related fatigue. This finding can be useful in planning exercise interventions as well as further research. The report stated a dose response effect on fatigue with exercise; however, the number and length of sessions was not a predictor of the degree of change in fatigue. These two findings seem to be contradictory. This aspect was not discussed by the authors.

The finding that resistance exercise interventions of moderate intensity were more effective than low-intensity or aerobic exercise is contrary to current National Comprehensive Cancer Network (NCCN) and American Cancer Society (ACS) guidelines, which do not mention resistance exercise and emphasize aerobic exercise. Moderate resistance exercise, such as weight machines, resistance bands, or free weights, may be a type that patients can maintain more easily. Use of theoretical models that incorporate issues of exercise behavior and behavior change may be more effective in providing support for the psychological components of adhering to an exercise program.