Motivation for different types and doses of exercise during breast cancer chemotherapy: A randomized controlled trial

Abstract

Background: Exercise is beneficial for breast cancer patients receiving chemotherapy but their motivation for different types and doses of exercise is unknown. Purpose: To examine exercise motivation before and after participation in a randomized trial. Methods: Breast cancer patients initiating chemotherapy (N=301) were randomized to a standard dose of 25-30 minutes of aerobic exercise (STAN), a higher dose of 50-60 minutes of aerobic exercise (HIGH), or a higher dose of 50-60 minutes of combined aerobic and resistance exercise (COMB). Patient preference and motivational outcomes from the theory of planned behavior (i.e., motivation, benefit, enjoyment, support, and difficulty) were assessed before and after the interventions. Results: At pre-randomization, breast cancer patients were significantly (p<0.001) more likely to prefer COMB (80.1%) than STAN (9.5%), HIGH (2.0%), or no preference (8.4%). At post-intervention, patient preference changed significantly (p<0.001) with an increase in the number of patients preferring HIGH (+5.1%) or no preference (+10.5%) and a decrease in the number of patients preferring STAN (-4.1%) or COMB (-11.5%). At pre-randomization, motivational outcomes were most favorable for COMB and least favorable for HIGH (all ps<0.001). At post-intervention, motivational outcomes improved significantly more for HIGH, resulting in uniformly positive motivational outcomes across groups. Conclusions: Initial motivation for different types and doses of exercise during breast cancer chemotherapy varied considerably but equalized after the interventions. If indicated, clinicians can recommend exercise interventions to breast cancer patients initiating chemotherapy that are contrary to their stated preference without jeopardizing motivational outcomes.

Acknowledgments: This work was supported by a grant from the Canadian Breast Cancer Research Alliance. Dr. Kerry S. Courneya is supported by the Canada Research Chairs Program. Christine M. Friedenreich is supported by a Health Senior Scholar Award from Alberta Innovates-Health Solutions and through the Alberta Cancer Foundation's Weekend to End Women's Cancers Breast Cancer Chair.