Check audio for 'Tu fais du sport?'. Does not seem correct.

Bonjour Hoyt ! We've now regenerated this audio example, please have a listen: https://kwiziq.learnfrenchwithalexa.com/my-languages/french/view/408 Merci et à bientôt !

Can you explain why there is "du" in this sentence: "Tu fais du mieux que tu peux" (You do the best you can). It's from a quiz. I also noticed "Elle fait de la natation". I'm assuming that there's a 'de" after faire when it comes to sports?