Why do we allow violent inmates to "pump iron" in prison. Do we really want inmates coming out of prison to be that much stronger than rest of population? Whats the point?
I suggest the following:
(1) Remove all exercise equipment and ban physical exercises outside of maybe 30min for cardio per day for all criminals convicted of violent crimes or all criminals if its easier.
(2) Install mandatory learning program to have some chance of rehabilitation - need to teach abstract subjects that expand the mind - like mathematics, physics, astronomy, foreign languages, history, arts. Employ resident religious figures to save costs. For those who have a chance, this would be greatest way to start their lives in new direction; for those who dont, this will be their worst punishment.