Increase in muscle mass at adolescence is probably caused by –

During adolescence, there is increased in muscle mass with loss of body fat. The maximum loss of fat and increase in muscle mass correspond to the time of peak hight velocity. "Both GH and gonadal steroids must be present for normal pubertal growth". __________ Laurence D. Steinberg Note - thyroid hormone and cortisol (adrenal steroids) are also required but this requirement is not different from that is required during childhood. Gonadal steroids (most imp) and GH are the major hormone for pubertal growth. So, best answer of this question would be all of the above.