Effects of prescribed aerobic exercise volume on physical activity and sedentary time in postmenopausal women: a randomized controlled trial.
The international journal of behavioral nutrition and physical activity. 2018;15(1):27
Plain language summary
Physical activity has emerged as an important lifestyle factor for primary prevention of numerous diseases, including postmenopausal breast cancer. The aim of this two-armed randomised controlled study was to examine the effects of a year-long prescribed aerobic exercise programme on physical activity levels and sedentary time in postmenopausal women. A total of 400 postmenopausal women aged between 50 – 74 years were randomised to one of the two groups; moderate (150min of exercise/week) or high (300min of exercise/week) volumes of aerobic exercise interventions. Results showed increased activity time in total and moderate-vigorous intensity/recreational physical activity, coupled with decreased sedentary time, in response to both volumes of prescribed physical activity. However, results also showed that physical activity and sedentary time returned to baseline following study completion. Authors conclude that total physical activity time can be increased with greater volumes of prescribed exercise. Furthermore, additional support and resources may be beneficial to promote the maintenance of increased physical activity and reduced sedentary time in the long-term.
BACKGROUND Physical activity has emerged as an important lifestyle factor for primary prevention of numerous diseases, including postmenopausal breast cancer. No study to date has assessed the acute and long-term effects of year-long aerobic exercise programs differing in prescribed exercise volume on physical activity and sedentary time in postmenopausal women. Therefore, we aimed to examine the effects of two moderate-vigorous intensity exercise doses on total, light and moderate-vigorous intensity physical activity times, and sedentary time in postmenopausal women during the year-long intervention and one year later. METHODS The Breast Cancer and Exercise Trial in Alberta (BETA) was a two-center, two-arm, 12-month randomized controlled trial that included 400 previously inactive postmenopausal women randomized to either 150 (MODERATE) or 300 (HIGH) minutes/week of aerobic exercise. Physical activity and sedentary time were assessed at baseline, 6- (intervention mid-point), 12- (prior to end of intervention) and 24-months (follow-up) with waist-mounted accelerometers (Actigraph GTX3®). Self-reported activity and sedentary time at baseline, 12- and 24-months was also assessed (Past Year Total Physical Activity Questionnaire and SIT-Q). Intention-to-treat analyses were conducted using linear mixed models and adjusted for baseline variables. RESULTS Both physical activity interventions led to increases in objective and subjective measures of total and moderate-vigorous intensity/recreational physical activity time, coupled with decreases in sedentary time, at 6- and 12-months compared to baseline. Additionally, greater increases in accelerometry-derived total physical activity time at 6- and 12-months, and self-reported recreational activity time at 12-months, compared to baseline were noted in the HIGH versus MODERATE groups. Decreases in total, light and moderate-vigorous intensity physical activity time, and an increase in sedentary time, in both groups were noted at 24-months compared to 12-months. A decrease in light intensity physical activity time in both groups at 24-months compared to baseline was also noted. CONCLUSION These findings have important health implications, suggesting that total physical activity time can be increased with greater volumes of prescribed exercise, but that additional support and resources could be used to promote the maintenance of these high levels of aerobic exercise participation following study completion. TRIAL REGISTRATION clinicaltrials.gov identifier: NCT01435005 (BETA Trial). Registred September 15th 2011 (retrospectively registered).