For better performance on the court, learn the facts about this essential nutrient.

Protein builds strong muscles, keeps your belly from grumbling, and is crucial for helping you get back on the court after a tough workout. But are you getting the right amount of it, at the right times? Here are four things every tennis player should know about protein.

1. It’s your hidden weapon for performance
Carbs fuel your workouts, but if you hit the court without having adequate protein in your diet, you risk more than just losing a match. “Tennis is a game of intermittent bouts of high intensity,” says Jenna Bell-Wilson, Ph.D., R.D., co-author of Energy to Burn: The Ultimate Food & Nutrition Guide to Fuel Your Active Life. Sprinting toward the net, racing back to the baseline, and suddenly stopping to get into position puts significant strain on your muscles. “You need protein to repair all the muscle damage that occurs over the course of a match and to build new muscle tissue,” Bell-Wilson says. “It’s crucial for helping you get stronger, recover faster and prevent injury.”

KEEP IN MIND: You don’t need to supplement with protein bars or powders.“Most Americans already get more than what they need,” says Susie Parker-Simmons, R.D., the dietetic adviser for the WTA tour. Nancy Clark’s Sports Nutrition Guidebook says the average recreational player should aim for 0.5–0.7 grams per pound of body weight daily (for a 150-pound player, that’s 75–105 grams). If you’re a competitive player, according to Clark, M.S., R.D., your needs may be slightly higher, up to 0.6–0.7 grams per pound. Growing teens need 0.7–0.9 grams per pound. Choose a protein-carbohydrate combination at each meal and you’ll easily reach your daily requirements, no gross-tasting bars required. Here’s a sample day: milk and cereal, a turkey and cheese sandwich, yogurt and berries, and grilled fish with rice and beans.

2. When you eat it makes a difference
From the moment you put down your racquet, your body begins the complex process of mending itself from the stresses you’ve put it through. “There is a window of time when certain enzymes are in place and ready to start the recovery process,” Parker-Simmons says. This crucial period, which lasts up to two hours post-workout, is the time to have a snack or drink that’s about three parts carbs and one part protein, with a small amount of fat. It’s especially important during a tournament, when you may be getting set for another match. Keep snacks in your racquet bag so you’re ready. Some options: low-fat chocolate milk, an energy bar with both carbs and protein, or a peanut butter and jelly sandwich.

KEEP IN MIND: Having a light snack with carbs and some protein before play also helps your performance. “Always go into a  match fed,” says Lona Sandon, M.Ed., R.D.,an assistant professor at the University of Texas Southwestern. Eat some yogurt with fruit 60–90 minutes before you hit the court. “You need the carbs for fuel,” Sandon says, “but having some protein is also important because it provides amino acids to get protein synthesis going, which helps build muscles.”

3. Protein is not a magic bullet for weight loss
If you haven’t tried a high-protein diet like South Beach or Atkins, you probably know someone who has. But even as higher-protein programs fall in and out of favor, remember that it’s your total calorie intake, rather than the amount of protein, carbs and fat you eat, that makes a difference in your waistline. A recent Harvard University study of more than 800 individuals found that whether they were eating high or average amounts of protein or low or high amounts of fat, as long as participants stayed on a reduced-calorie diet their average weight loss over a two-year period remained the same.

KEEP IN MIND: For tennis players looking to drop a few extra pounds, a low-carb program isn’t going to help your game. “Most of the success shown on the high-protein diets is among people who are typically sedentary,” Sandon says. “If you’re active, you need those carbs to keep you fueled or you’ll find yourself fatigued much more quickly during play.” Plus, Sandon says, there’s one big advantage to including protein in your diet: “Protein is more satiating, so you’ll feel fuller longer.”

4. All protein sources are not created equal
Protein is made up of 20 basic building blocks, known as amino acids. Unlike fat or carbs, which are stored as glucose, your body can’t store amino acids; it needs a fresh supply daily. We can make or modify about half of the amino acids we need to function, but we have to get the rest (known as essential amino acids) from food. Complete proteins come from meat, fish and dairy and have all the amino acids your body needs to function. Incomplete proteins, from fruits, vegetables, grains and nuts, are missing one or more essential amino acids, which is why vegetarians and vegans need to consume a wide variety of foods with protein, including nuts, seeds and beans, each day.

KEEP IN MIND: Choose whole foods over expensive protein powders. “Eggs, meat, dairy and fish provide all the protein you need,” Sandon says. Although there’s some evidence that whey powders contain an amino acid that can help in performance, a glass of milk or other dairy products contain more than enough to help your body function at its best.