Pain is an interesting thing. When you first feel pain, it's scary and, usually rightly so, is the body telling the mind to stop something. The problem is that in order to get better in most athletic endeavors, athletes must push their bodies into an area that often causes some sort of pain[1].
A couple things eventually happen. First is the athlete starts to associate pain with progress. This is actually a bad thing since pain should always remain as valid feedback and signal a person to think about the actions they are taking. Second and more import is that the athlete accepts the pain and deals with it. Like most things in life, it sucks a lot more until you know what to expect. For example, getting punched in the face causes pain, but more than that it causes surprise. Remove that surprise and even if the pain is the same, the athlete will now react in a more sensible way from the punch.
For reference, I don't do any long distance (5k is what I maintain) running but have always played various sports, trained in MA, and primarily powerlift now (at least until the ski slopes open!).
[1] After experiencing all sorts of pain over the years there are definitely good pains and bad pains. IMHO, it takes time and experience to recognize what pains are what :)
I am an "endurance athlete" that regularly rides my bike 60+ miles. It's not a serious physical pain, like when you twist an ankle - I know when I am doing my body harm. It's pushing past a major amount of discomfort in order to achieve a goal. Granted, doing so without proper nutrition and hydration can cause injury, however your body is better off when you push through your concept of "too much".
Seriously, my body used to tell me "oh god stop stop stop this is too much" after 30 miles of flat riding. Now it take 60 miles of hilly riding to experience that, and it's not nearly as strong.
I guess to sum it up, it isn't normal pain, it's more of a mental wall that you push past.
I have done a fair amount of MA training and I think the best way to think about pain is recovery time. If I do this it will take my body less than two days to recover and it hurts but, that's reasonable if I want to progress. The next level of pain takes longer than that to recover from and should be avoided at all [1] costs. Fast recovery pain still has its downsides if you needed to escape from a burning building or run from a tiger right after a serious workout you would be slower and have a higher risk of injury etc. But, the modern world is fairly safe so itβs reasonably safe to ignore that kind of pain.
Unfortunately recovering from injury takes longer as we age so reasonable habits for a 19 year old can get a 35 year old into serious trouble. Also, you tend to get a mix of short and long term dammage so repeating low level pain can still be a sign your doing significant long term dammage.
[1] People are often willing to do longer term damage in major contests and fights. How reasonable this is depends on your personal goals.
You make a great point about recovery time. Many people incorrectly assume that if you finish your workout hurting then it was a good workout. The problem is that as you get better it becomes much harder to hurt and it becomes a recovery management challenge. What people seem to have anecdotally found is that more workouts which can be recovered from in a day or two are much better than the giant ones that leave you hobbling for a week. I think this becomes even more important where there are skills involved beyond only strength (like MA).
A couple things eventually happen. First is the athlete starts to associate pain with progress. This is actually a bad thing since pain should always remain as valid feedback and signal a person to think about the actions they are taking. Second and more import is that the athlete accepts the pain and deals with it. Like most things in life, it sucks a lot more until you know what to expect. For example, getting punched in the face causes pain, but more than that it causes surprise. Remove that surprise and even if the pain is the same, the athlete will now react in a more sensible way from the punch.
For reference, I don't do any long distance (5k is what I maintain) running but have always played various sports, trained in MA, and primarily powerlift now (at least until the ski slopes open!).
[1] After experiencing all sorts of pain over the years there are definitely good pains and bad pains. IMHO, it takes time and experience to recognize what pains are what :)