Point taken John and there is some truth to that. I suspect "back in the day" the good old boys just sweated it out and all of them were beat up by the end.
I recall Richard Petty commenting on how he had dismissed "driving shoes" for years, he always wore cowboy boots. It's what real men did. Eventually he was talked into trying a pair of racing shoes. He was like SO excited at this point in his interview. Going on and on about how he couldn't believe the difference it made, those driving shoes are great!
Today the racing is so competitive the drivers need every edge they can get. That means being alert and fresh as much as possible at the end as at the beginning. Hence, regular gym "work out's" are just the way it is now.