Does resistance training alter plasma myostatin but not IGF-1 in healthy men?
Myostatin may play a role in exercise-induced increases in muscle size, its circulating levels decreasing with resistance training in healthy men. Exercise of the whole body versus the elbow flexors alone did not provide a supplementary stimulus in altering resting plasma IGF-1 or myostatin, or in increasing muscle strength or size. Thus, by default, growth factor responses local to the muscle may be more important than circulating factors in contributing to muscle hypertrophy with resistance training.
Fetal and adult human skin fibroblasts retain their differential proliferative response to TGF-β when cultured in the presence of fibronectin and unpolymerized or polymerized collagen.