Twelve-week resistance training decreases myostatin level and improves insulin sensitivity in overweight-obese women

Myostatin is a secreted protein that acts as a potent inhibitor of skeletal muscle growth. Inactivation of myostatin increases muscle mass and decreases insulin resistance. The aim of this study was to determine if the improvement in insulin resistance after resistance training is associated with a decline in serum levels of myostatin. A sample of 19 obese-overweight women (age= 23.2±3.4 yr, body mass index= 29.18±1.72 kg/m 2 ) were assigned to resistance training (n= 10) and control (n= 9) groups. Resistance training was performed 3 times weekly for 12 weeks. Body composition, metabolic parameters, and myostatin were measured prior to and after the intervention. Insulin resistance improved significantly after 12wk of resistance training (p<0.05), but without changes in adiposity parameter such as body weight, body mass index, fat percent and waist circumference (p>0.05). Also, following the resistance training, muscle strength and lean body mass were significantly increased (p<0.05). Concurrently, myostatin concentration significantly decreased in response to resistance training (p<0.05). In conclusion, 12-wk resistance training program increases insulin sensitivity in obese-overweight women, and this improvement was associated with decreased myostatin levels but is independent of measurable changes in body fat. These data suggest that resistance training-induced alterations in myostatin levels may have a role in resistance training-induced insulin sensitivity improvement.