Predictors of follow-up exercise behavior 6 months after a randomized trial of exercise training during breast cancer chemotherapy

Abstract

Exercise during breast cancer chemotherapy is beneficial but it needs to be maintained into survivorship to optimize long-term benefits. Here, we report the predictors of follow-up exercise behavior 6 months after a randomized exercise trial in breast cancer patients. Breast cancer patients (N = 242) initiating adjuvant chemotherapy were randomly assigned to usual care (n = 82), supervised resistance exercise (n = 82), or supervised aerobic exercise (n = 78) for the duration of their chemotherapy. At baseline and postintervention, data were collected on demographic, medical, behavioral, fitness, psychosocial, and motivational variables. At 6-month follow-up, participants were mailed a questionnaire that assessed exercise behavior over the past 6 months and were categorized as either meeting both aerobic and resistance exercise guidelines, either exercise guideline, or neither exercise guideline. Two hundred one (83.1%) participants provided 6-month follow-up data with 85 (42.3%) meeting neither exercise guideline, 74 (36.8%) meeting either exercise guideline, and 42 (20.9%) meeting both exercise guidelines. In multivariate regression analysis, seven variables independently predicted the likelihood of meeting exercise guidelines at follow-up including higher pretrial exercise (beta = 0.23; P = 0.002), younger age (beta = -0.15; P = 0.028), breast conserving surgery (beta = 0.15; P = 0.033), strength improvements (beta = 0.15; P = 0.028), lower postintervention fatigue (beta = 0.13; P = 0.067), a more positive attitude (beta = 0.12; P = 0.086), and lower postintervention body mass index (beta = -0.11; P = 0.105). Exercise behavior 6 months after a randomized trial was predicted by a wide range of demographic, medical, behavioral, fitness, psychosocial, and motivational variables. These findings may help facilitate the uptake of exercise behavior during the transition from breast cancer patient to survivor.