Impact of a combined resistance and aerobic exercise program on motivational variables in breast cancer survivors: a randomized controlled trial.

BACKGROUND Short term exercise interventions have been shown to be beneficial for breast cancer survivors soon after treatments but longer term adherence is needed. PURPOSE To examine the effects of a supervised exercise program on motivational variables in breast cancer survivors using Self-Determination Theory (SDT). METHOD Sixty breast cancer survivors were randomized in a cross-over design to either an immediate exercise group (IEG; n = 30) that exercised from baseline to week 12 or a delayed exercise group (DEG; n = 30) that exercised from week 12 to 24. SDT variables were assessed at baseline, 6, 12, 18 and 24 weeks using the Behavioral Regulation for Exercise Questionniare-2 and the Basic Psychological Needs Satisfaction Scale. RESULTS Fifty-eight participants completed the follow-up assessments and achieved a 61.3% adherence rate. Analyses of variance revealed significant time by group interactions for almost all psychological needs and motivations that favored the exercise intervention time periods. For example, autonomy increased in the IEG from baseline to 12 weeks by 2.0 points compared to the DEG where scores decreased by 0.1 points (mean group difference = 2.0, p < 0.001). The cross-over results further supported the main findings. CONCLUSION Supervised exercise soon after breast cancer treatments may help to develop a positive exercise motivational profile among breast cancer survivors that could portend longer term adherence.