The other way is to just keep criminals in prison until they age enough that their hormones change and they no longer feel the urge to violence. The good thing

The other way is to just keep criminals in prison until they age enough that their hormones change and they no longer feel the urge to violence. The good thing about this is that it works very consistently and predictably. If he's in prison, he can't rape, murder, or brutalize anyone else (prison crime notwithstanding). Human males naturally enter their criminal phase around age 16 and exit it around 30-35. The factors governing this are biological and can literally be measured in the bloodstream. The stuff you're talking about can help some people, but for many... you can't train someone into lower testosterone levels.