Curious about weaponizing the human body. They had a piece on it with this program:
https://www.youtube.com/watch?v=uHKPNbtSyHI
I'm not so sure about their dramatized example, but it is clear you can make your bones pretty hard and your muscles pretty strong, regardless. The question is: How much? How hard and strong can human bone become? Would you have had knights who could smash baseball bats with their bare limbs (based off that piece about what a knight is expected to do, I can imagine so)?
What does this mean for combat, in the end? As impressive as these bones and muscles seem for sport and civilian life, a sword swung by a weak man will still cut into the strongest man. At the same time, strength and endurance can be useful for war, allowing you to keep up the fight.