Alex Honnold climbed El Capitan - a 3000ft vertical cliff in Yosemite - with no rope. Kind of makes running around in circles look like a sport for wimps, to be honest.
So there are three key variables people think about when they talk about diet:
Health (lifespan, and rates of diseases)
Wellbeing (how you feel)
Athletic performance
I think vegan is best for health, based on the data I've seen. Specifically, whole food plant based.
Wellbeing - this varies from person to person. One guy eats tons of meat and feels great. Another person eats that and feels like crap, feels great on a vegan diet.
As for athletic performance - the jury is out. At ultra races, you have vegans dominate (Scott Jurek), and keto guys (Zach Bitter). Not many elite athletes eat vegan because not many people are vegan. You can look at how diet impacts sports another way - elite runners back in the 70's and 80's tended to have terrible diets. Bill Rodgers pounded back donuts, oreos, mayonnaise by the spoonfull, drank a bunch, etc. Yet he still ran sub 2:10 in the marathon. Did all those donuts help him? Or maybe diet isn't such a huge deal as we thought when it comes to running well? It's hard to know. Jim Walmsley, while vegetarian, lives off of pizza, beer, and clif bars, from what he's said. Is that optimal? He does have the 50 mile road WR. That's why the jury is out. The data is all over the place. Maybe - and I suspect this is the case - provided that you are getting enough nutrients to support the activity you are doing, whether those nutrients comes from plants or animals doesn't matter. Also, picture someone growing up eating a certain diet, and doing amazing at a sport at a young age. Why would the drastically change their diet? What they are doing is working. Why screw around with it? It's a big risk to do so. The odds of any athlete with promise drastically changing their diet from ANY one diet to another is very low. They may clean up their diets by reducing processed food. But how many elite athletes are going keto? How many are going carnivore? Very, very few. It's too risky. Plus, most people screw up going vegan. I admit it's a hard diet to do properly. So the odds of someone who is an elite athlete going vegan, having poor results, not wanting to sort out the issues and would rather get back to their tried and true diet is very, very high. So yes, the jury is very much out.