The idea of lose it or use it when it comes to exercise is a little bit inappropriate. As a surgeon, I see a significant number of patients who are injured by their exercise program, because rather than listening to their body when they hurt, they follow the no pain, no gain philosophy.
Ischemic muscle pain, which is the muscle burn you get when you exercise, is beneficial, as it means that you are gaining muscle. However, people can go in the other direction, where they are overstressing and damaging their joints. It gets to a point where you stop building muscle and start to wear away your joints.
When you get to your mid-40s, joints become more vulnerable to cartilage injuries and can start to wear away. If you are overstressing the cartilage due to exercise, this can lead to cartilage injury. This is the time to understand that exercise is important, but start to think about reducing the intensity and not pushing so hard.
