Credible science has shown us for decades that tennis players who require muscle energy levels high enough to sustain two or more hours on the court, must eat primarily complex carbohydrates to adequately fuel supplies. Low carbohydrate diets can impair performance and cause health and medical issues. Examples of complex carbohydrates are beans, oatmeal, 100 percent whole-wheat bread, quinoa, barley, potatoes, and sweet potatoes, rice. Fiber-rich carbohydrates provide the main fuel for the brain and muscles.
 
Physical demands of tennis
Tennis is an anaerobic sport, characterized by repeated bouts of high intensity activity (points), followed by longer bouts of recovery, with most points lasting less than 10 seconds. These repeated bouts of high- intensity activity using muscle work is fuelled by Adenosine triphosphate (ATP) – the biochemical way to store and use energy.
 
These stores of ATP are only sufficient to assist with muscle contractions for approximately three seconds. However, as these stores of ATP are quickly burned during a tennis point, the body produces more ATP for muscle contractions through a series of related chemical reactions, calling on the body’s stores of glycogen to produce ATP. Carbohydrates are the glycogen that fuels ATP. Glycogen is the storage form of glucose and carbohydrates (CHO) in humans.

After a tennis point; the body begins to replenish ATP stores in the muscles and remove lactic acid and other anabolic waste from muscles. Research shows that tennis players can replace up to 70 % of ATP stores within 30 seconds of ending a point. [Tennis players must start points within 20 seconds according to ITF rules, and often start points within 10 seconds of the last point ending, so not optimal for the competitors.]
 
As the intensity of physical activity increases, the percentage of energy generated from carbohydrates increases while the percentage from fat decreases. Therefore, during a tennis match, a single player burns more calories from glycogen (for ATP creation) than fat.
Energy and macronutrient requirements for tennis play

Caloric needs
Tennis players expend 7.5-11 kcal/min in practice. Study reports of total caloric expenditure during match play estimated to be between 649 kcal to 3244 kcal for male players from 60-300 minutes and for 443 kcal to 1107 kcal for female players from 60-150 minutes during matches.

Because of the short point play nature of tennis, most points last less than 10 seconds and require 300-500 bursts of energy over the course of a match. Tennis training and play is anaerobic work, which is fuelled primarily by carbohydrate coming from glycogen stores. Studies showed that after checking blood glucose levels of elite players during tournament play, researchers concluded that stored glycogen was enough to provide energy for 100 minutes of exercise.
Carbohydrates
Because of the highly anaerobic nature of tennis, the most up to date sport nutrition experts recommend that competitive tennis players consume a high – carbohydrate diet between 6-10g/kg/day to synthesize adequate muscle glycogen energy stores. These guidelines also recommend that players consume 30-60 g/hour during matches to maintain energy balance and meet muscle glycogen needs. Players should also consume 11.5g/kg body weight of carbohydrates within 2 hours after matches, when glycogen synthesis is highest, to facilitate full replenishment of carbohydrate energy stress.
Protein
Protein needs for tennis players range from 1.2-2.0g/kg /day.
Recovery recommendations suggest that consuming 0.3 g/kg after play and strength training and every three to five hours thereafter. In reality most tennis players will need between 3-5 ounces (20-35 grams) of lean proteins in meat or vegetable protein twice per day.
Fat
Dietary fat contributes to part of the energy expenditure during tennis workouts and matches, especially in longer matches.
Players should be discouraged from consuming less than 20 percent of their energy from fat as they may not meet their essential fatty acid needs and may suffer from fat deficiency issues such as underweight, fatigue, suppressed hormones and poor recovery and healing.
Application to tennis performance
The most appropriate calorie intake for tennis players before training and matches is should primarily be complex carbohydrates. Complex carbohydrates foods should be consumed in meals and snacks in the 1-4 hours before play in a 1-4 g/kg. During the first hour of activity, research recommends that tennis players replace lost nutrients by drinking water, then switching to small amounts of carbohydrates, in gels and sport drinks after one hour. This can be accomplished by consuming 30-60 grams of carbohydrate per hour in higher carbohydrate sport food products.
 
After a tennis activity, players should replace depleted glycogen stores, lost water and depleted micronutrients (electrolytes.) Carbohydrates are absorbed into the muscles more efficiently if consumed within two hours of activity. Studies recommend consuming 30 grams of carbohydrates, 15-25 grams of protein and less than 7 grams of fat within 30 minutes to maximize full recovery.
CARBOHYDRATE SOURCES IN GRAMS:
Breads: 15-gr carb
1 slice of bread (whole grain)
½ small bagel
½ English muffin
½ hotdog/hamburger bun
1 pancake or waffle (5”)
½ pita bread (6”)
1 small plain roll
1 tortilla (6”)
1 small muffin
Cereals: 15-gr carb
½ cup bran cereal
½ cup granola
½ cup cooked cereal
¾ cup dry cereal (plain)
¾ cup puffed cereal

Pasta/Grains: 15-gr carb
1/3 cup cooked pasta
1/3 cup cooked rice
½ cup cooked grains
Fruits: 15-gr carb
7 dried apricot
1 apple, pear
1 small banana or ½ large banana
¾ cup blueberries or raspberries
1/3 of a whole cantaloupe
1-cup melon cubes/balls
15 cherries
15 grapes
2 figs
2 plums
½ cup canned “light” fruit
1 large kiwi
¾ cup fresh pineapple
½ of a whole mango or papaya
3 medium prunes
2 tbsp. raisins
1¼-cup strawberries
1¼-cup watermelon cubes/balls
Milk/Yogurt: 15-gr carb
10 oz. skim,
 1%, 2% or whole milk
½ cup evaporated milk
1-cup plain yogurt

Vegetables/Beans: 15-gr carb
½ cup cooked beans
1/3 cup baked beans
½ cup corn or green peas
1 small baked potato
½ cup cooked potatoes
10 -15 French-fries
½ cup spaghetti sauce

Vegetables: 5-gr carb
1 cup cooked or 1 cup raw:
asparagus, broccoli, carrots, collard greens, cabbage, cauliflower, green beans, eggplant,
tomato, peppers, spinach, zucchini
½ cup tomato or V-8®juice
½ cup applesauce