Calories are the basic units or packages of energy that fuel our body's daily activities. We get our energy by burning the calories stored in our body's tissues. When we exercise, our body burns more calories. In the body, energy is produced primarily from fat and glucose. Fat exists in muscles and in fat cells. Glucose is a sugar and is readily converted into energy. Glucose is stored as glycogen in muscles and in the liver. When the body needs energy and consumes all of the available glucose, it can create more glucose from its glycogen stores. A proper diet prior to and during a workout or competition can provide a better balance of nutrients so that the opportunity for the body to run out and become exhausted will take longer. General recommendations for caloric intake range from 2,000 to 6,000 calories per day. The primary goal is to develop a diet that provides enough calories (and maximizes glycogen stores) to closely match the calories you will burn during a workout or competition.
Carbohydrates are basically substances that serve as sources of energy. Types of carbohydrates found in different foods include complex carbohydrates (starches, fruits, vegetables), which contain fiber, and simple sugars (juice, desserts, sweets). Complex carbohydrates provide the best source of energy for the weekend warrior or competitive athlete. Complex carbohydrates also have important nutrients that are not available from other food sources or groups, and they are the most important for peak athletic performance. Carbohydrates are stored in the muscle and liver as glycogen. Glycogen stored in the liver is used mainly for blood-sugar control, while glycogen stored in the muscle is used for energy during exercise. A diet that is 60 to 65 percent carbohydrates is necessary to maintain the glycogen stored in your muscles. If you are engaged in heavy athletic activity or competition on successive days, you should maintain a diet of 65 to 70 percent of carbohydrates. Glycogen stored in muscle is important because it gives you the needed energy reserve during exercise. This is what allows you to perform at maximum levels. Glycogen can last for up to two hours of nonstop exercise, but will depend on your physical condition. As exercise continues, and glycogen stored in muscle is used up, a greater amount of energy will be generated from fat stores. Our muscles need both fat and glucose to function, so as glycogen stores diminish, we are subject to fatigue.
The body's most concentrated source of energy comes from fat. Fat contains nine calories per gram, whereas carbohydrates and protein have only four calories per gram. Since carbohydrates are only available in a limited amount during exercise, the most important function of fat is to provide extra calories to the body. Increasing your dietary intake of fat during exercise will not improve the use of fat as a fuel. It is the fat already stored in your body, coupled with general conditioning that will improve the use of fat as a fuel to drive your peak athletic performance. Therefore, it is important to maintain some level of fat in your body through your diet. And furthermore, good general conditioning will help you to use fat as fuel. Some of the more usual sources of fat are oil, butter, margarine, salad dressing, sauces, fried foods, and gravy.
Protein has four calories per gram and is made up of subunits called amino acids. The average person requires .8 grams of protein per kilogram of body weight each day. For athletic people and those engaged in competitive activities, it is recommended to have 1.5 to 2.0 grams of protein per kilogram of body weight. The increase in protein requirements is mainly a result of increased caloric needs due to the increase in activity level of the athlete. Protein drinks, protein bars, and other related supplements are not usually necessary to increase protein. Most diets can easily meet increased needs without supplementation. Increasing protein beyond what the body needs will not contribute to athletic performance or increased muscle mass. Extra protein cannot be stored. Additionally, too much protein also increases the risk of dehydration because when it is used as energy, its byproduct-urea-must be eliminated from the body through the urine.
Vitamins and Minerals
Deficiencies in certain vitamins can hinge upon peak athletic performance. If a wide variety of nutritional foods are included in the diet and the increased energy intake of the athlete is met, then vitamin and mineral requirements will most likely be met. Iron is a mineral that needs special attention, as it plays a role in the transport of oxygen to active muscle. Iron deficiency anemia can affect athletic performance. Women tend to be at higher risk of iron deficiency due to menstruation. Vegetarian athletes also need to be aware of iron levels, since most good sources of iron are in meat and poultry. Sports anemia, sometimes found in early stages of training, is not related to iron deficiency and appears to be the body's adaptation to exercise. Sports anemia is a pseudoanemia that is sometimes experienced by athletes in the early stages of training as a result of an increase in plasma volume. It is not caused by a deficiency of dietary iron-unlike anemia of iron deficiency, the number of red blood cells is normal. An increase in blood volume causes a dilution of red blood-cell concentration. There is no treatment for sports anemia and it will not affect athletic performance. Calcium intake in conjunction with weight-bearing activities, such as lifting weights, will reduce the risk of developing osteoporosis. Estrogen levels in the female, alcohol and caffeine intake, as well as family history are other factors influencing the risk of osteoporosis.
During exercise, we sweat due to an increase in heat production. Water or other fluids serve to cool down our body. If we do not replace fluids fast enough to offset the fluids lost through perspiration, we will become dehydrated. Dehydration will result in decreased performance, and if not resolved in a timely manner, could result in a host of medical problems. Those engaging in exercise or competition-from the weekend warrior to the competitive athlete, cannot depend on thirst for fluid replacement and should, therefore, force themselves to drink even if they're not thirsty. Commercial sports beverages that contain electrolytes may enhance absorption and will also provide a carbohydrate source. Cold water will also be absorbed more rapidly and will decrease body temperature. It is recommended to use a sports beverage in an extended competition such as a marathon or vigorous workout that lasts for more than one hour. Water is fine for shorter competitions or workouts.
Pre-Workout or Competition
Research shows that proper food and fluid intake prior to working out or engaging in a competition will improve endurance. Results also show that athletes who eat prior to exercise feel better and find the activity less rigorous than those who choose to fast. The athlete who risks eating and drinking too close to a competition or workout may suffer from gastrointestinal distress such as nausea and cramping.
Replacing carbohydrates and fluids during exercise that is more than an hour in length can delay fatigue and enhance endurance by maintaining muscle glycogen stores. Fatigue can be delayed by consuming 30 to 60 grams of carbohydrates per hour (120 to 240 calories from carbohydrates). Carbohydrates are best provided at regular intervals.
The immediate goal after a workout or competition should be the replenishment of glycogen stores. Additionally, carbohydrate ingestion should begin as soon as possible, with the ingestion of 30 grams of carbohydrate, or 120 calories, within thirty minutes. Carbohydrate intake should continue at two-hour intervals for up to four hours. If this does not occur, then glycogen repletion and endurance will be impaired. The equivalent of two cups (one pint) of fluid should be ingested for each pound of body weight lost. If exercise or competition is in excess of one hour, your body is at risk for excessive sodium and potassium loss. While most electrolytes are replaced at the post-workout or competition meal, sports beverages will be beneficial if the athlete is not hungry or unable to have an appropriate meal.