I found this recipe in a magazine to make your own sports drinks this summer, and every other summer for that matter.
Mix one part fruit juice and one part water and add a pinch of salt
Yeah that's it.
After seeing this "recipe" (The quotes are because I would call this less of a recipe and more of a method) I decided to google "Make your own sports drink" and found many other recipes. Some called for tea while others called for juice. Some called for the water while others didn't. I even found one that added baking soda. The thing in common with all of them though was the pinch of salt.
I think that you could make this with any yummy juice or tea you like, water it down to reduce the sugar content if you like but basically just add a pinch of salt to whatever you are drinking.
Have fun and stay safe this summer!