I've seen people's comments on meeting gymnasts, especially Simone Biles, and most of what they say is how muscular they are. She is like 4'8" pure muscle. I've seen the male gymnasts, and they look like miniature tanks. If I'm not mistaken, they are the overall fittest athletes because of what they do.

These athletes at the Olympics and in most competitive sports, don't spend their time training and playing against people who don't challenge them.

I think this is a bit extreme. They are regular people just like us. A lot of the NBA players have been shown to mess around in smaller basketball leagues. Phelps has been shown to kick back and relax when it is far from the competitions. They can't always go 80-100 percent in their training and games all the time. They will definitely kick it up a notch when a big event is coming up.