Insulin-like growth factor 1 (IGF-1)

No they are not steroids. They are made up of proteins

Jane V. Higdon has written:

'Effects of acute heavy resistance exercise on serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels in older men and women' -- subject(s): Exercise for the aged, Insulin-like growth factor-binding proteins, Physiological aspects, Physiological aspects of Exercise for the aged, Somatomedin

I.G.H. stands for Insulin-like Growth Factor, a hormone that plays a role in cell growth and development in the body. It is similar in structure to insulin and is produced mainly by the liver in response to stimulation by growth hormone.

John Sun has written:

'The effects of insulin-like growth factor binding protein-1 on pre- and postnatal cardiac morphology and function'