HIGHLIGHTED TOPIC Physiology and Pathophysiology of Physical Inactivity Aerobic exercise training conserves insulin sensitivity for 1 yr following weight loss in overweight women

Fisher G, Hunter GR, Gower BA. Aerobic exercise training conserves insulin sensitivity for 1 yr following weight loss in overweight women. J Appl Physiol 112: 688–693, 2012. First published December 15, 2011; doi:10.1152/japplphysiol.00843.2011.—The objectives of this study were to 1) identify the independent effects of exercise (aerobic or resistance training) and weight loss on whole body insulin sensitivity and 2) determine if aerobic or resistance training would be more successful for maintaining improved whole body insulin sensitivity 1 yr following weight loss. Subjects were 97 healthy, premenopausal women, body mass index (BMI) 27–30 kg/ m. Following randomized assignment to one of three groups, diet only, diet aerobic, or diet resistance training until a BMI 25 kg/m was achieved, body composition, fat distribution, and whole body insulin sensitivity were determined at baseline, in the weight reduced state, and at 1-yr follow up. The whole body insulin sensitivity index (SI) was determined using a frequently sampled intravenous glucose tolerance test. Results of repeated-measures ANOVA indicated a significant improvement in SI following weight loss. However, there were no group or group time interactions. At 1-yr follow up, there were no significant time or group interactions for SI; however, there was a significant group time interaction for SI. Post hoc analysis revealed that women in the aerobic training group showed a significant increased SI from weight reduced to 1-yr follow up (P 0.05), which was independent of intra-abdominal adipose tissue and %fat. No significant differences in SI from weight reduced to 1-yr follow up were observed for diet only or diet resistance groups. Additionally, multiple linear regression analysis revealed that change in whole body insulin sensitivity from baseline to 1-yr follow up was independently associated with the change in V̇O2max from baseline to 1-yr follow up (P 0.05). These results suggest that long-term aerobic exercise training may conserve improvements in SI following weight loss and that maintaining cardiovascular fitness following weight loss may be important for maintaining improvements in SI.