Predictors of Adherence to Different Volumes of Exercise in the Breast Cancer and Exercise Trial in Alberta

Chelsea R Stone; Christine M Friedenreich; Rachel O'Reilly; Megan S Farris; James R Vallerand; Dong-Woo Kang; Kerry S Courneya

doi:10.1093/abm/kay057

Predictors of Adherence to Different Volumes of Exercise in the Breast Cancer and Exercise Trial in Alberta

Ann Behav Med. 2019 Mar 28;53(5):453-465. doi: 10.1093/abm/kay057.

Authors

Chelsea R Stone^{1

2}, Christine M Friedenreich^{1

2

3}, Rachel O'Reilly¹, Megan S Farris¹, James R Vallerand⁴, Dong-Woo Kang⁴, Kerry S Courneya⁴

Affiliations

¹ Department of Cancer Epidemiology and Prevention Research, Alberta Health Services, Calgary, Alberta, Canada.
² Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
³ Department of Oncology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
⁴ Faculty of Kinesiology, Sport, and Recreation, University of Alberta, University Hall, Edmonton, Alberta, Canada.

PMID: 30020401
DOI: 10.1093/abm/kay057

Abstract

Background: Exercise demonstrates a dose-response effect on many health outcomes; however, adhering to higher doses of exercise can be challenging, and the predictors of adherence may differ based on exercise volume.

Purpose: To examine the predictors of adherence to two different volumes of aerobic exercise within the Breast Cancer and Exercise Trial in Alberta (BETA).

Methods: In BETA, we randomized 400 inactive but healthy postmenopausal women to either a moderate volume (150 min/week) or a high volume (300 min/week) of aerobic exercise for 1 year. We collected data on several predictors of exercise adherence at baseline and used linear and mixed-effect models to determine predictors of exercise adherence to exercise volume and overall.

Results: Adherence was higher in the moderate-volume group (84.5%) compared with the high-volume group (75.2%; p < .001). There were no statistically significant interactions between predictors of exercise adherence and exercise volume. Overall, we found that exercise adherence was predicted by randomization group, body mass index (BMI), employment status, and physical health. Adherence was 8.6% lower in the high-volume versus moderate-volume group, 6.7% lower for women working full time versus not, 0.8% lower per BMI increase of 1 kg/m2, and 0.5% higher per unit of physical health.

Conclusions: Adherence to high-volume aerobic exercise was more challenging than for moderate-volume aerobic exercise, but the predictors of adherence were similar. Moreover, few factors were major predictors of exercise adherence in this setting suggesting that well-controlled efficacy trials that produce high adherence rates may reduce the influence of individual characteristics on exercise adherence.

Trial registration: NCT1435005.

Trial registration: ClinicalTrials.gov NCT01435005.

Keywords: Aerobic exercise; Exercise determinants; Exercise intervention; Postmenopausal women; Predictors of adherence; Randomized controlled trial.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Alberta
Exercise / physiology*
Female
Health Behavior / physiology*
Health Surveys
Humans
Middle Aged
Postmenopause / physiology*

Associated data

ClinicalTrials.gov/NCT01435005