Interestingly, I've just being doing a bit of revision around Chronic Kidney Disease, and interpreting blood results. Reminded me'self that some of the parameters we explore (eGFR) are skewed as a result of dense muscle mass. (A problem for the medics, not the bodybuilder/pilot.)
It's gotta be safer than sitting on the couch watching Big Brother.
From experience, use of steroids is becoming increasingly prevalent, without wishing to preach, I have come across a few nasty tumours as a result.