Most exercisers can get away with gulping water after a workout, but endurance athletes--anyone training for a marathon or playing hours of tennis in the hot sun--need to put extra effort into replenishing the minerals flushed out via sweat. Sure, electrolytes come standard in sports drinks and energy bars, but they're usually accompanied by a hearty helping of calories and added sugar. A better way to replenish the electrically charged particles needed to maintain fluid balance in the body and aid the muscle and nerve functions necessary for athletic performance: Pick up a spoon and fork. "Foods contain so many more electrolytes, as well as vitamins and other health-protective compounds," says author and sports dietitian Nancy Clark, RD. Here, how to replace five key electrolytes with healthy, whole foods.