Great. You just lost another tennis game. That’s the fifth loss in a row. What’s the deal? You’re healthy as a horse, you’re physically fit and you’ve got your game face on. Why are you on a losing streak? It could be the stiff competition, it could be a run of bad luck or it could be something simple, like a lack of nutrition.

Athletes expend a great deal of energy and require more calories and fluids than most people to fuel their bodies. When you’re training for a competition or participating in one, the last thing on your mind may be nutrition. However, did you know that nutrition is crucial to performance and could be a deciding factor in whether you lose or win?

Like any game, good nutrition has some basic rules. Athletes should drink plenty of fluids and eat three meals a day plus a variety of healthy snacks to meet their increased caloric needs. These rules apply whether you’re training or competing. However, there are some special considerations you should make before and after a game.

During competition, the body uses glucose to supply the muscles with energy. Athletes get glucose by eating a variety of carbohydrate-rich foods, such as fruit, vegetables and grains. To give your body a boost, eat a light meal high in carbohydrates one to four hours before a game. Try to avoid foods that are high in protein, which will slow down digestion, as well as foods that could cause gas or other digestive problems. To keep your body hydrated, drink 20 fluid ounces of water or sports drink one to two hours before a game and 10 fluid ounces every 15 minutes until the game starts.

During competition, the body uses up glucose stores and loses potassium, sodium and fluids through perspiration. All of these substances will need to be replenished. To restore them, eat foods high in carbohydrates, potassium and sodium after a game, and drink 16 fluid ounces of water or sports drink for every pound you have lost.

Whether you play tennis, basketball, soccer or some other sport, you need to maintain a balanced diet that fuels your body before, during and after competition. Only then can you play your best. That’s more important than the results, isn’t it?