IF YOU’RE DOING circuits in the park, drinking regular water before, during, and after ought to cover it. (The American College of Sports Medicine recommends downing 17oz within two hours of training.) But if your workout is jogging for 90 minutes or more and you sweat heavily, you risk losing electrolytes—minerals like chloride, potassium, and sodium that allow you to perform optimally.

At that point, it could be helpful to have a banana on hand, or a drink like Aquahydrate, which offers increased pH as well as electrolytes, helping the water buffer acid in the body. A study published by the Wilderness Medical Society showed that subjects who drank water fortified with electrolytes achieved better hydration than those drinking water alone, and could afford to drink less water as a result.