SPORT SCIENCE - Professional Tennis Registry

Glycemic Index in Determining Pre-Match MealsGenerally, an active tennis player will require more calories, and those would come mainlyfrom carbohydrates. Not all carbohydrates are created equally however, as some takelonger to digest, and hence, produce energy more slowly for the body. Some foods aredigested quickly to become energy sources. Since they break down quickly, they raise theblood glucose and insulin. These foods are known as having a high glycemic index (GI).Diabetics have been long aware of these foods, and try to restrict their intake. Foods thatbreak down slowly and don’t raise blood glucose and insulin rapidly have low GI.If a player is in a three hour match and needs some energy quickly late in the competition,sport drinks and sugary foods provide quick energy, since they have high GIs. If a player iseating hours before a match, and wants to use the food more effectively as energy, s/hemay choose to eat foods with low GIs. For example, before a late morning match, a playermay choose a breakfast of bran cereal with blueberries and milk. Milk, blueberries (andmost fruits) and bran are low GI foods.After a tough match, a player should replenish for the next day’s competition, and usinghigh GI foods immediately after a match can be helpful. In addition, a light protein snack(e.g., yogurt) is best utilized by the body in the minutes after a match. Sometimes, anathlete might eat some pretzels, a moderate to high GI food. Bananas, commonly used fortennis matches, are moderate GI foods.The International GI database, as run by the University of Sydney (SUGiRS, SydneyUniversity Glycemic Index Research Service) is an excellent source to look up the GIs offoods.www.glycemicindex.com© USDAPTR Practical On Court Applications for Sport Science 21