Exercise training and habitual physical activity: a randomized controlled trial.

Background: Exercise training reduces adiposity and risk of cardiovascular disease. However, the combined effects of habitual free-living physical activity and aerobic training on waist circumference, weight, fitness, and blood pressure in postmenopausal women are unknown.

Purpose: To evaluate the effects of habitual physical activity levels during aerobic training on weight, waist circumference, fitness, and blood pressure.

Design: Secondary analysis of an RCT. Original data collected April 2001 to June 2005 and analyzed in 2012.

Setting/participants: Postmenopausal women in a supervised exercise trial.

Intervention: Women (n=325) were randomized to 4, 8, or 12 kcal/kg per week of aerobic training or a control group for 6 months. All outcome measures were collected at baseline and follow-up. Changes in dependent variables within each training group were evaluated across tertiles of pedometer-determined habitual physical activity outside exercise training sessions.

Main Outcome Measures: Changes in waist circumference and weight.

Results: Reductions in waist circumference were significantly greater with higher steps/day accumulated outside exercise training compared to lower levels in the 4 (high: -4.8 cm vs low: -1.4 cm, p=0.03); 8 (high: -4.2 cm vs low: -0.4 cm, p=0.03), and 12 kcal/kg per week groups (high: -4.1 cm vs low: -0.7 cm, p=0.05). For all groups, p-trend≤0.03. A trend was observed for greater weight reduction with higher steps/day in the 4 kcal/kg per week group (p-trend=0.04) but not for the other exercise doses. No effects were observed for blood pressure or fitness measures (all p>0.05).

Conclusions: In postmenopausal women, higher habitual physical activity while participating in aerobic training was associated with greater reductions in central adiposity, and was supportive of weight loss compared to lower levels.