Minerals, Vitamins and Supplements

Most of the creatine found in the body is in skeletal muscle where it exists mostly as creatine phosphate (51), an important storage form of energy that buffers ATP and thus serves to maintain the bioenergetic state of exercising muscle. The average dietary intake is about 2 g/d in omnivores (51) and negligible amounts in vegetarians since it is found primarily in muscle tissue. Even though creatine can be synthesized extra muscularly from amino acid precursors , serum and skeletal muscle creatine concentrations have been found to be lower in vegetarians compared to nonvegetarians. Thus there is some thought that vegetarian athletes in particular may benefit from creatine supplementation. Currently, however, little is known about long-term effects or training benefits of creatine supplementation (64). although this increase in lean mass was not statistically significant (52). In the authors practice over the past year increasing numbers of recreational and competitive athletes and coaches have shown interest in creatine supplementation. With adults one can review current the scientific data and the expense of supplementation, (as well as the benefits of eating a good diet) and let the athlete/coach make their own decision. With children and adolescents, a prudent approach would be to discourage supplementation.
In addition to creatine, athletes are likely to inquire about a number of other supplements and ergogenic aids. While only caffeine (53) and bicarbonate currently appear to have potential, other aids include citrate, phosphate(54), branched-chain amino acids (55), carnitine, choline (55), chromium (56) and DHEA (70). A discussion of these is beyond the scope of this article.

Nutrition Before, During and After Exercise

Pre-Event Meal. Nutritional intake in the meal before a competition or exercise session should increase fuel stores, provide adequate hydration and prevent both hunger and gastrointestinal distress. Studies have shown that consumption of between 1 and 5 g of CHO/kg BW one to four hours before endurance exercise has the potential to improve endurance performance by as much as 14% and is also thought to benefit high-intensity performance. concentrations towards the end of exercise , and may also confer an advantage by providing a slow-release source of glucose without an accompanying insulin surge(57). On the other hand, ingestion of a liquid CHO supplement immediately before exercise ( 5 min) is appropriate and has been found to improve performance during endurance (13) and resistance exercise (58).Specific pre-event food choices, however, may need to be individualized. Athletes sensitive to gastroesophageal reflux should avoid caffeine, chocolate, sulfur-containing vegetables and concentrated sources of fat. Those experiencing frequent nausea, cramps and vomiting should pay attention to meal timing and not eat within 3 or 4 hours before exercise(59).. Also, liquid meals are more easily digested and may be helpful for avoiding the pre-game nausea sometimes associated with solid foods (60). Guidelines for fluid consumption include consuming at least 2 cups fluid about 2 hours before exercise, followed by another 2 cups approximately 15-20 min before endurance exercise (19).
Supplementation During Exercise. Carbohydrate ingestion at levels between 45 and 75 g/h have been shown to benefit prolonged, moderate intensity exercise ( 2 h) and variable intensity exercise of shorter duration (11) presumably by maintaining blood glucose levels as endogenous glycogen stores become depleted. Ingestion of fluid replacement beverages easily provide CHO requirements while simultaneously meeting fluid needs.