AAS can block cortisol from binding to the muscle cell's receptor sites, which diminishes the breakdown process. Less muscle breakdown means less muscle fatigue which would allow a pitcher to recover more quickly from a nine-inning outing.
Besides all of the known negative side effects of using steroids just for ergogenic reasons, there is also the uncertainty of what exactly you are taking. Last month, federal Drug Enforcement Administration agents arrested the owners of an Alabama-based online pharmacy on charges that they filled hundreds of illegal prescriptions for anabolic steroids for clients across the country.
Results wise, users should expect extreme strength increases and weight gain in a relatively short 2-4 week period. Weight gain upwards of 20lbs in 4 weeks is not unheard of with this incredibly potent compound. Although subcutaneous water gain would be minimal, intramuscular water retention should be expected. This is due to inhibition of 11b-hydroxylase and build-up of mineralcorticoids which encourage salt and water retention within the muscles. The most obvious physical effects will be improved vascularity, aggressive muscular pumps, and oily skin.
While methyldrostanolone can stack well with most other steroids, it should never be stacked with another methylated (17aa) steroid.