Hydration

• Water regulates your body temperature, is needed for energy metabolism and minimizes cardiovascular stress. A 2 percent loss in body weight from dehydration leads to a 10 percent decline in performance. Your body also needs fluids to recover properly. Dehydration can be chronic, so drink at least 50 fluid oz. a day plus extra water to replace sweat losses. Hydration also means maintaining the proper electrolyte balance. Consume sports drinks or electrolyte tablets to maintain electrolyte levels during long exercise sessions.
  
  

Carbohydrate Loading

• An athlete burns about 1 g of carbohydrate per minute through vigorous exercise. The more glycogen (carbohydrates stored in the muscles and liver) an athlete can store, the longer he can exercise before exhausting his supply. A trained athlete on a high-carbohydrate diet (deriving 75 percent of its calories from carbohydrates) stores about 880 g of carbohydrate--2.6 times what he would store on a standard 45 percent carbohydrate diet. To effectively saturate your liver and muscles with glycogen, consume a high-carbohydrate diet for three days before competition, along with plenty of water.
  
  

Caffeine

• Caffeine is a powerful supplement for endurance athletes. Your body derives much of its energy from fat, with the rest coming from muscle glycogen. Caffeine releases more fatty acids into the bloodstream for use as fuel. With more energy coming from fat, your stored glycogen is spared, prolonging time to exhaustion. Caffeine also reduces the rate of perceived exertion (makes exercise feel easier) for some athletes. Caffeine loses its effectiveness if you use it regularly, so cut back in the four days before competition. Also, caffeine is a diuretic, so it may interfere with hydration levels.
  
  

Creatine

• The body creates the amino acid creatine naturally, deriving the rest from food. Some athletes supplement creatine to increase power output and lean muscle mass to enhance performance for short, intense efforts. Using creatine in conjunction with carbohydrate increases the muscles' creatine uptake. Only take creatine in recommended doses, and never if you have high blood pressure or kidney or liver problems.
  
  

Banned Substances

• The World Anti-Doping Agency has banned several substances such as EPO and anabolic steroids because they are dangerous. Other synthetic substances that may appear in over-the-counter medications and supplements were banned because they provide an unethical performance advantage. It is the athlete's responsibility to know what is in her supplements and whether they are safe and legal. Never take banned substances that could ruin your career or your health just to gain an unfair competitive advantage.