Injuries incurred while young have an evil way of saying "hello" again down the road, when one gets older.
They heal, but their effects linger, and sometimes increase over time.
I'm only in my mid-40s, but I get reminders of injuries from my 20s whenever I over-exert, or sometimes when the weather changes.
So, no, I wouldn't go shooting rifles with your buddies; I'd also take a break for a while from MA training. Then again, I still have goals of being relatively mobile when I get really old.