Progressive Metabolic Adaptations to Low Intensity Exercise Training and Weight Loss

the investigators first aim is to determine the effect of low intensity exercise (without weight loss) on insulin sensitivity, muscle lipid metabolism, and factors regulating these processes in skeletal muscle after 1 day, 2 wks, 12 wks of training, and again after 3 days without exercise in obese adults. the investigators second aim is to determine the effect of combining low intensity exercise training with 10% weight loss on insulin sensitivity, muscle lipid metabolism, and factors regulating these processes in skeletal muscle.

Although a single 40 minute session of exercise at a low exercise intensity will not improve insulin sensitivity, the investigators anticipate adaptations after two weeks of exercise training (6 session/wk; 12 session total) will improve insulin sensitivity and be accompanied by a reduction in fatty acid intermediates and a reduction in markers for pro-inflammatory activation in muscle. the investigators anticipate changes in insulin sensitivity, fatty acid partitioning, and pro-inflammatory markers the day after the last session of a 12 wk training program (without weight-loss) will be similar to that measured after 2 weeks of training. the investigators anticipate insulin sensitivity, accumulation of fatty acid intermediates, and pro-inflammatory activation will be markedly improved after 10% weight loss when measured the day after exercise. the investigators would expect the improvements in Insulin sensitivity, accumulation of fatty acid intermediates, and markers of inflammatory stress will be significantly attenuated when measured 3 days after the most recent exercise session, but beneficial effects of 10% weight loss on these metabolic endpoints will persist when compared with before weight loss.