Review of exercise studies in breast cancer survivors: attention to principles of exercise training

Objectives Research supports the use of exercise to improve quality of life and reduce the side effects of breast cancer treatment, such as fatigue and decreased aerobic capacity. Previously published reviews have focused on reporting the outcomes of exercise interventions, but have not critically examined the exercise prescriptions. The purpose of this review is to evaluate the application of the principles of exercise training in the exercise prescriptions reported in intervention studies for breast cancer survivors. Methods Databases were searched for randomised controlled trials of exercise in women diagnosed with breast cancer. Data were extracted to evaluate the application of the principles of exercise training, the reporting of the components of the exercise prescription and the reporting of adherence to the exercise prescription. Results Of the 29 papers included, none applied all principles of exercise training. Specificity was applied by 64%, progression by 41%, overload by 31%, initial values by 62% and diminishing returns and reversibility by 7% of trials. No study reported all components of the exercise prescription. Conclusion The application of the principles of exercise training varied greatly, and reporting of the exercise prescribed and completed was incomplete. When principles of exercise training are applied to the development of exercise protocols, there is greater confidence that non-significant findings reflect lack of efficacy of exercise rather than deficiencies in the prescription. Incomplete reporting of the exercise prescription and adherence to the prescription limits the reproducibility of the intervention, and the ability to determine the dose of exercise received by participants.