If you bike or run an hour or more, you’re not just losing fluids. You’re also sweating out electrolytes like sodium and potassium. You could replace them with a sports drink or you could chase down some water with a glass of tomato juice. It’s filled with potassium and sodium. One eight-ounce glass delivers six-and-a-half times the sodium and 15 times the potassium you’d get from your standard sports drink.