Staggering the difference between pro athletes in all sports when I was growing up (59 now) and guys today. However that probably was not always the best thing. When you see how long it takes for guys to recover from concussion, now that the medical community knows what to look for, God only knows how much additional damage those guys did to themselves. Really the same is true at all levels. I know there were football games I continued to play in when I was just plane gonzo.
Hard to even understand how the pros continued to play at such a high level under the circumstances.