Interaction of insulin like growth factor-1 and resistance training on skeletal muscle mass and function

In the present study, the effects of IGF-1 overexpression, resistance training and their interaction on muscle mass and function were examined in both mouse and rat models. In addition, the effect of IGF-1 overexpression on the reversal of training-induced adaptations in skeletal muscle mass and function during varying lengths of detraining was measured. The resistance training consisted of a ladder climbing protocol. Overexpression of IGF-1 was localized to one hindlimb via injections containing adeno-associated virus and the contralateral hindlimb served as an internal control. IGF-1 overexpression alone resulted in an increase in mass and peak tetanic tension (Po) of the flexor hallucis longus (FHL) muscle in both rat and mouse model. Eight weeks of resistance training alone resulted in an increase in mass and peak tetanic tension (Po) of the flexor hallucis longus (FHL) muscle only in rat model. The combination of resistance training and IGF-1 overexpression resulted in further increase in muscle mass and Po in rat model, giving evidence of an additive effect. Overexpression of IGF-1 significantly attenuated the loss of muscle mass in FHL during 12 weeks of detraining. These data suggest a beneficial effect of combination of resistance training and IGF-1 overexpression on skeletal muscle mass and function.