A study examined the role growth hormone (GH) on muscle hypertrophy and the viscera of rats undergoing functional overload, which to a method of producing muscle hypertrophy in a specific animal model. For instance, if the gastrocnemius muscle is removed from an animal, the
plantor flexors of its ankle will be functionally overloaded when the subject is forced to walk.
The remaining muscle then experiences hypertrophy. the experiment cited, functional overload was induced by removing the of the calf, the gastrocnemius and soleus, and leaving the plontoris muscle intact. The latter is on important flexor (it points toes downward). After receiving one milligram per of growth hormone for six weeks, the OH-treated rats showed a dramatic increase (65%) in the weight of the muscle subject to functional overload.
However, the plantaris not subject to functional overload didn't hypertraphy in response to GH. So it seems that in the absence of overload, GH treatment does not produce significant changes in muscle mass. However, the heart muscle did in these rats.
I've never been impressed with the effects of GH, and this study certainly reinforces that view. GH supplementation may hove a profound on those deficient in the hormone, but otherwise, its effects are unenviable.