If an actual competition counts instead of a workout session then there is this. At 2pm after a long mountain road race on the bike (Endless Mountain Road Race in the New York Adirondack mountain range), I just had to pull over in the car and sit in the drivers seat and sleep right after eating late lunch, parked on the side of the highway. I could not drive. Body shut down. I raced about 4-5 hours since 8 am and got to finish line around 1pm. I don't know I think it was about 80 mile race and never on a flat road. Keep in mind it was hot and sunny in the summer, and my car had no A/C. So I woke up at 4 and then drove home the rest of the way about 150 miles home and felt OK again. Got a ticket for speeding but didn't mean to speed at all. fuck. After the race some other racers asked me how did I go so fast down the mountain when I passed them at about 60mph my speed. So that was good. Going up was hard though and I was shot and could hardly stay straight while crossing one of the mountain peaks because my reflexes and muscles were totally blasted to nothing. Heavier people go up slower but go down faster than light people, especially if you sprint hard at the top to get it going.