Mod Note:And to think all this time I've believed I've been having fun playing D&D. Now that I know that the attribute system is not realistic, I realize that fun must have been an illusion.
A Grizzly Bear has a strength of 19. Those athletes are not that strong. No Human naturally can be.
I dunno... Hafthor is probably stronger than a grizzly bear. They don't even lift!
But it would be hard to test, what with all the claws.
How about we consider a more obvious real-world analog: the amount of weight a person can lift. According to the Player's Handbook:
Your Strength score determines the amount of weight you can bear. You can push, drag, or lift a weight in pounds up to twice your carrying capacity, or 30 times your Strength score.
The world record for deadlift is 501kg, or 1104.5 lbs., set by Hafthor Bjornsson (1104.5/30=36.8) So here's what a Strength of 37 looks like in real life:

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.