Loading your bones close to the breaking point does make them stronger. At least as long as you give them time to recover in between, otherwise you get a stress

Loading your bones close to the breaking point does make them stronger. At least as long as you give them time to recover in between, otherwise you get a stress fracture. It's a balancing act. Do it well and you get stronger, overdo it everything spirals downwards. Same for most of the rest of your body. If something gets close enough to killing you, it will definitely make you weaker.