Human (Castaneda et al., 2000; Marcell et al., 2001) and animal (Edwall et al., 1989; Ullman et al., 1990) studies suggest that IGF-1 is an important regu- lator of skeletal muscle growth. Circulat- ing IGF-1 is required for muscle and bone growth in adolescence and for the maintenance of muscle mass and strength in the adolescent period as well as in adulthood. Serum level of IGF-1 not only affects proliferation of peripheral tissues but also affects CNS development and proliferation (Jeon and Ha, 2014). For example serum IGF‐1 induces neuro- genesis during brain development and has an important role in repair processes of traumatic brain (Madathil and Saat- man, 2014). It was found that this IFG-1- induced neurogenesis is enhanced by exercise (Trejo et al., 2002). IGF-1 in the blood reach its peak during adolescence and is maintained at somewhat lower levels during adulthood (Hameed et. al., 2002).