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High-Volume Exercise Effectively Cuts Body Fat in Postmenopausal Woman, May Reduce Breast Cancer Risk

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Key Points

  • Three hundred minutes of vigorous exercise was significantly better at reducing total body fat, subcutaneous abdominal fat, body mass index, and waist-to-hip ratio in inactive postmenopausal women than shorter volumes of exercise.
  • Body fat increases postmenopausal breast cancer risk; physical activity may decrease breast cancer risk through adiposity changes.
  • A dose-response effect of exercise on total fat mass and several other adiposity measures, including abdominal fat, especially in obese women, provide a basis for encouraging postmenopausal women to exercise at least 300 minutes per week.

A study comparing the effects of moderate to vigorous aerobic exercise on body fat in inactive postmenopausal women has found that 300 minutes of vigorous exercise each week was superior in reducing total fat and other adiposity measures, especially in obese women, than shorter amounts of exercise. The study findings by Friedenreich et al suggest additional benefit of higher-volume aerobic exercise for adiposity outcomes and possibly a lower risk of postmenopausal breast cancer. The study is published in JAMA Oncology.

Study Methodology

The researchers enrolled 400 inactive postmenopausal women in the 1-year Breast Cancer and Exercise Trial in Alberta (BETA Trial) conducted in Calgary and Alberta, Canada. The eligible women were aged 50 to 74, had a body mass index (BMI) of 22 to 40, were inactive, disease-free, nonsmokers, and nonusers of exogenous hormones.

The BETA trial was a two-armed, randomized dose-comparison trial of 5 days a week of aerobic exercise for 30 minutes per session (moderate volume) or 5 days a week of 60-minute sessions (high volume), achieving 65% to 75% of heart rate reserve for at least 50% of each session. Participants were asked not to change their usual diet.

Study Results

Of the 400 participants, 384 provided baseline and follow-up adiposity measurements. Median (interquartile range) adherence at full prescription for the high- and moderate-volume groups was 254 (166–290) and 137 (111–150) minutes per week, respectively.

Mean reductions in total fat were significantly larger in the high- vs moderate-volume group (least-squares mean difference = −1.0% [95% confidence interval [CI] = −1.6% to −0.4%], P = .002). Subcutaneous abdominal fat and waist-to-hip ratio decreased significantly more in the high-volume group (least-squares mean difference = −10.8 [95% CI = −19.5 to −2.2] cm2, P = .01, and −0.01 [95% CI = −0.02 to 0.00], P = .04, respectively).

Changes in weight and intra-abdominal fat were not significantly different between groups (least-squares mean difference = −0.7 [95% CI = −1.6 to 0.2] kg, P = .11, and −1.5 [95% CI = −5.9 to 2.9] cm2, P = .50, respectively). Some dose-response effects were stronger for obese women.

“In previously inactive postmenopausal women, a 1-year prescription of moderate to vigorous exercise for 300 min/wk was superior to 150 min/wk for reducing total fat and other adiposity measures, especially in obese women. These results suggest additional benefit of higher-volume aerobic exercise for adiposity outcomes and possibly a lower risk of postmenopausal breast cancer,” concluded the researchers.

Christine M. Friedenreich, PhD, of the Department of Cancer Epidemiology and Prevention Research, CancerControl Alberta, Alberta Health Services, is the corresponding author of this study.

The study was funded by the Alberta Cancer Foundation. The study authors reported no conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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