There's a lot of carnivore athletes out there that would disagree with you.

If you're curious about this, you may want to listen to some interviews with Dr. Tim Noakes. He's the originator of the whole "carb loading" concept, which introduced the idea that you needed to eat a lot of carbs before and during anything athletic.

He has since completely renounced that idea (after developing diabetes himself) and I just listened to an interview with him. Very interesting, especially how he was persecuted after renouncing the previous pro-carb ideas.