What should I know about sports nutrition?
Athletes often ask us what they should be taking to improve performance. As with many such questions, the answers depend on the athlete's age, the sport, co-existing medical conditions, and dietary habits.
At the very least, most supplements marketed to athletes to improve performance essentially are worthless! The only supplements proven to enhance performance are caffeine and creatine, bt each of these has its own problems and dangers.

Caffeine
Caffeine is a legal stimulant and can enhance performance in certain sports involving speed. But, it can hinder performance in such sports as archery and shooting, where fine motor control and a steady hand are essential.

Creatine
Creatine can boost strength and power but it does so at the expense of increased weight gain. Creatine may be helpful for sports such as weight lifting, body building, baseball and football linemen. However, because it increases body weight it can hinder performance in sports where maintaining lean body weight is critical. Creatine should also be avoided in teenagers and younger athletes because of increased physiologic load placed on the kidneys and the lack of long-term studies investigating its safety in these age groups.

Make sure you buy your creatine from a reputable supplier. Many companies either "cut" their creatine with other powders or they add other supplements to the creatine, some of which may be banned substances by the NCAA or US Anti-doping Agency or may be harmful. You should only use pure creatine monohydrate.

The correct way to take creatine is by "cycling." Mix 5 grams of pure creatine monohydrate in juice and take it once daily for one month. Then stop for at least a month to allow a "washout" period. Higher loading doses used to be recommended, but that approach has fallen out of favor since it does not appear to be necessary and puts an unnecessary load on the kidneys.

Protein Supplements
Proteins are the building blocks of the body and amino acids are the building blocks of proteins. There are 9 "essential" amino acids or amino acids that are not synthesized in the body and need to be obtained through diet. Protein builds muscle and it rebuilds and repairs muscle after exercise. During exercise up to 15% of the energy needs are generated from protein breakdown into glucose.

Protein supplements have long been used by athletes to improve performance. However, there is no scientific support for protein supplementation as a performance enhancer. Protein shakes and bars have gained popularity with the rise of high protein - low carbohydrate diets. Most athletes need less protein than they think and they need more carbohydrates than they believe. A healthy balanced diet provides the protein needs for most athletes. Athletes in certain sports, such as weight training and throwing field events may benefit from a small amount of protein supplementation. Too much protein though puts a large burden on the kidneys, which have to filter the excess protein and amino acids from the blood.

According to the American Society of Exercise Physiologists (ASEP), the protein requirement for general fitness/nutrition is about 1.0 gram of protein per kilogram body weight per day. For moderate-to-high intensity athletic training, recommended protein requirements are 1.0-1.5 grams per kilogram body weight per day. For intense athletic training, approximately 2.1 grams of protein per kilogram body weight per day of protein is suggested.
Be careful when choosing "protein bars" as many are just glorified candy bars. They are high in fat and carbohydrates and should not be used for protein supplementation. Read the labels carefully.

Carbohydrates & Fats
The advent of low-carb diets has cast an undeserved bad shadow on carbs. Carbs are the mainstay of sports nutrition. These are not the enemy! Carbs provide the necessary quick fuel and energy for actively contracting muscles. They also provide a sort of "flame" that helps break down fats more efficiently, providing energy for endurance events. Stored carbohydrate is referred to as "muscle glycogen" (MG). During aerobic exercise, it is important to have sufficient MG stores in order to reduce the amount of protein breakdown occurring during activity.

The key is carb selection. Avoid simple carbs and instead choose complex carbs such as fruits and vegetables. Certain pasta manufacturers, such as Barilla and Hodgson Mills, are now selling high-protein whole grain pastas. During endurance exercise, however, simple carbs provide immediate fuel for sustained activity. Sports drinks such as Gatorade or Powerade or easy-to-carry fruits such as bananas or orange slices can provide quick carbohydrates.

Likewise, fats are necessary and can provide a source of energy for sustained endurance activities. Fat is also essential for the utilization of fat-soluble vitamins. Unsaturated fats, such as olive oil and canola oil, preferred over saturated fats such as butter. Approximately 30% of dietary calories should be in the form of fat, with most of that being mono-unsaturated fats.

Growth Hormone Promoters
Numerous manufacturers have been marketing products claiming to stimulate release of growth hormone within the body. Such claims are completely unfounded. These products break down in the stomach and have no proven effect on growth hormone production. Growth hormone levels need to be measured by blood tests and the only way to increase growth hormone levels is by injection.

Vitamin Supplements
Because of the increased of oxidative stress and the formation of free radical molecules, athletes should at least be taking a multivitamin and women should add iron. Additional antioxidants, such as vitamin C, coenzyme Q-10 and omega-3 fish oil should be added.