1/ Bonds has not lost any of his muscle since the heavy duty scrutiny. 2/ Athletes often have a lot of undeveloped fast-twitch muscle. This can enlarge to an amazing degree if and when the athlete switches to an intense strength training/ bodybuilding regime. 3/ Not all, but many of the injuries associated with steroid use are simply the downside of any added strength's potential to overwhelm weak links in the body structure and added weight's stress on same.The effect is largely the same when the muscle is built entirely naturally. Weight training itself can be looked upon as an unnatural activity, as it increases one's muscle mass without enlarging their supportive bone structure, requires extra skill training to balance fine motor skills with new strength, and, in addition to setting the stage for many injuries athletes suffer , actually -causes- a good number of them.
When a person weight trains naturally, they strengthen the connective tissues and increase bone density just as they increase muscle mass and lean body composition. This is the body's way of preventing injury.
When weight training is supplemented with steroids, human growth hormone injections or similar aids, muscle growth progresses so rapidly and unnaturally that the bones and connective tissues can't keep up. This results in injury.
But, just because an athlete is injured, does not mean that they are on the juice. Athletes have been injured since the dawn of athletics. It's not proof.
The multitude of findings detailed in this book, however, are pretty much proof. Some people might want the smoking syringe sticking out of Barry's belly as the only proof they'll accept, but I don't drink that koolaid.
Even with natural weight training, the tendon and ligament's strengthening lags -way- behind the muscle's. If the training schedule doesn't take this into consideration, they may never catch up. Yes, steroids make the difference more severe, but even a natural bodybuilder's strength gives him the power to hurt himself in ways that others will most likely never do. Also, certain body structures can't benefit from training as much as others; an athlete's feet won't ever tolerate 230lbs sprinting as well as they handled 170. Such problems don't only show up in the primary area, because 'corrections' in posture, to avoid pain, interfere with correct technique elsewhere in the body. Added strength on an already successful athlete is a component that requires serious re-rehearsal of all skills to assimilate without inferior performance and/or injury.