Speaking of baseball, during Fantasy Camp at least half the players blow out their legs during camp, and most are in the 30-40 age range and thought they were in shape.
Then you have associated arm injuries, sliding injuries, arm fatigue, bruises from bouncing balls abd HBP. I have learned the hard way what is needed and survived pretty well this year though I was sore at the banquet, I was still walking normally. It was amusing to see 35 year olds hobbling up to collect their award.
All the newbies said it was a LOT harder than they expected. There is at least one guy who is 74, but I'm probably next oldest.
Of course, a player who is say 30 and a real player won't have these issues except for the typical baseball injuries over 162 games. They all say they were all bruised up and sore after the first month.