Food for Athletes: Eating to Optimize Performance

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Food for Athletes: Eating to Optimize Performance 2016-12-26T17:38:11+00:00

Food for Athletes: Eating to Optimize Performance

By Terry Zeigler, EdD, ATC 

Because of recent diet fads, marketing campaigns, and general misinformation, athletes have been led to believe that protein is the essential nutrient for an athlete. In fact, you would probably find that most young athletes involved in a strength training program or power sport are also consuming protein supplements because somebody told them that additional protein would help the athlete add lean muscle mass.

While proteins are a critical component of body tissues, they are not the best source of energy to fuel an athlete’s body. In fact, proteins are only converted to an energy source if other nutrients (carbohydrates and fats) cannot meet the energy demands of the body.

Because of the myths about proteins circulating amongst athletes, athletes tend to consume way more protein than their body’s actually need. Unfortunately, the extra protein consumed in an athlete’s diet takes the place of the one nutrient that the athlete really needs to fuel his/her body – carbohydrates.

Carbohydrates in general have incurred a bad reputation over the past decade. Popular fad diets that are high protein and low carbohydrate have been marketed as a healthy means to lose weight. However, this type of diet is counterproductive for athletes.

For athletes, carbohydrates need to be the highest nutrient source (carbohydrates, protein, and fats) and should make up approximately 65 percent of the athlete’s total dietary intake in a day. Athletes require a diet high in carbohydrates because of the following (Benhardt, D., 2006):

• Carbohydrates provide a good source of energy during practices and competitions
• Carbohydrates provide energy to meet the body’s caloric needs
• Carbohydrates help with muscle recovery after exercise
• Carbohydrates help store energy within the muscle tissue in the form of glycogen
• Carbohydrates provide a quick and easy source of energy to maintain blood sugar levels

How are Carbohydrates used as an Energy Source for Athletes?

While there are a wide variety of sources of carbohydrates in foods, once carbohydrates enter the body, they are all broken down into glucose during the digestive process. Simple carbohydrates are easier to breakdown and will provide the quickest source of energy for the muscles. Complex carbohydrates take a little longer for the body to break down, but will also eventually be broken down into glucose. The primary difference between the two is the rate that it takes the carbohydrate to breakdown into glucose.

The most important point for athletes to understand is that “glucose is the main source of fuel for muscular activity, and the higher the exercise intensity, the greater the reliance on glucose as a fuel” (Benhardt, D., 2006). When the athlete’s body runs out of glucose, muscular fatigue will set in.

To help the body maintain glucose levels, glucose is stored in the body in a number of different ways. This is important to understand because athletes participating in high intensity or endurance sports need to eat a diet rich in carbohydrates prior to their practices/competitions in order to store as much glycogen in the muscle tissue as possible.

The largest storage for glucose is in the muscles in the form of muscle glycogen (approximately 350 grams). Glucose can also be stored in the liver in the form of liver glycogen (90 grams), and finally in the circulating blood stream (approximately 5 grams). When comparing the three storage sources, it becomes obvious that the largest organ for storing glucose is the muscles. In fact, the more muscle mass an athlete has, the more glycogen that an athlete can store.

However, there is a limit to the amount of glycogen that can be stored effectively in the muscles, liver, and bloodstream. Once a saturation point has been reached, any excess glucose is then stored as fat.

While glucose levels in the blood and stored liver glycogen are primarily fueling the central nervous system (keeping the athlete alert and focused), energy necessary to contract the muscles of the body for exercise is obtained through the breakdown of stored glycogen in the muscle. This process is known as glycolysis.

While the physiological process of glycolysis is complicated, the bottom line is that the energy necessary for an athlete’s muscles to contract originates from the food source of carbohydrates.

What type of carbohydrates should an athlete eat?

While there are many types of carbohydrates, not all are beneficial for an athlete’s body. The type of carbohydrate that an athlete should be consuming is based on how quickly the carbohydrate is broken down into blood glucose.

This measurement is known as the glycemic index. Foods in which the carbohydrate is quickly broken down into blood glucose have a higher glycemic index rating, while foods with higher fiber content tend to have a lower glycemic index rating.

While it is generally recommended for people to consume carbohydrates that have a low to moderate glycemic rating, there are times when an athlete might benefit from foods with a high glycemic index. Those times would be during and immediately after exercise. Examples of food that are classified as having a high glycemic index rating (greater than 70) include the following:

Baked potato…………………….85
Corn Flakes………………………..84
Pretzels…………………………….83
Instant mashed potatoes……….83
Gatorade…………………………..78
Vanilla Wafers……………………..77
French Fries……………………….75
Graham crackers………………….74
Saltine crackers…………………..74
Honey………………………………73
Bagel……………………………….72
Watermelon………………………72
White bread………………………70

Examples of foods that fall within the moderate classification of the glycemic index rating (55-70) include the following:

Wheat bread…………………..68
Shredded Wheat……………..67
Grape Nuts……………………..67
Croissant………………………..67
Wheat thins……………………67
Life cereal………………………66
Cream of Wheat………………66
Cantaloupe……………………..65
Soda…………………………….65
Raisins……………………………64
Vanilla ice cream………………..60
Cheese Pizza…………………….60
Blueberry muffin………………..59
Power bars………………………58
Pear………………………………58
Banana……………………………56
Frosted Flakes……………………55

Examples of foods that fall within the low classification of the glycemic index rating (less than 55) include a lot of pastas and the following:

Special K…………………………54
Cheese tortellini………………..50
Linguini…………………………..50
Chocolate bar…………………..49
Carrots…………………………..49
Peas……………………………..48
Oatmeal…………………………48
Orange juice……………………46
Grapes…………………………..46
Macaroni…………………………46
Baked beans……………………44
Orange…………………………..43
Snickers bar……………………..41
Apple juice………………………40
Tomato soup……………………38
Apple……………………………..38
Chocolate milk…………………..35
Spaghetti………………………..33
Fettuccini………………………..32
Grapefruit………………………..25
Cherries…………………………..22

How many carbohydrates should an athlete consume in a day?

The amount of carbohydrates recommended for athletes is between 55% and 65% of their total dietary intake. This has been more specifically calculated for athletes depending on the level of intensity of their sport.

Daily recovery from a moderate-duration, low intensity exercise program is recommended to be 5-7 grams of carbohydrates per kilogram (1 kg = 2.2 lbs) of body mass per day (Burke, L & Coyle, E., 2004). For example, a 155 lb athlete would need to consume 350-490 grams of carbohydrates (1,400 – 1,960 kcal) throughout the day to meet his/her energy needs.

Daily recovery from a moderate to heavy endurance exercise program is recommended to be 7 – 12 grams of carbohydrate per kilogram of body mass per day (Burke, L. & Coyle, E., 2004). This would mean consuming somewhere between 1,960 and 3,360 kilocalories of carbohydrates for a 155 lb athlete.

An athlete engaging in an extreme exercise program (4+ hours per day) is recommended to consume 10 – 12 grams of carbohydrate per kilogram of body mass per day. If the athlete is not able to maintain his/her weight, more carbohydrates would need to be consumed to match the athlete’s caloric expenditure.

Choosing Nutrients Wisely

Once an athlete understands that the primary fuel source for his/her muscles is actually carbohydrates and not protein, an athlete can then make the appropriate changes in his/her food intake to provide the fuel necessary to keep his/her body performing at the highest levels. If an athlete does not consume enough carbohydrates in his/her diet, the athlete’s body can run out of stored glycogen and blood glucose. This will cause the athlete to fatigue both mentally and physically.

Athletes also need to know that once glycogen stores are depleted, the body will breakdown protein sources to provide fuel for the muscles – this includes muscle tissue. So if an athlete does not consume enough carbohydrates, the athlete’s body may actually begin to breakdown muscle tissue as a source of fuel. This is counterproductive for any athlete.

Knowing how to properly fuel the body is important for every athlete. While all of the essential nutrients are important for the health of the body, carbohydrates are the essential fuel for the athlete.

References

Benardot, D. (2006). Advanced Sports Nutrition: Fine-Tune your food and fluid intake for optimal training and performance. Human Kinetics: Champaign, IL.

Burke, L & Coyle, E. (2004). Nutrition for athletes. Journal of Sports Sciences 22(1): 39-55.

Diabetesnet.com “Glycemic Index”, (Accessed on January 13, 2011).