Caffeine ingestion and performance of a 1,500-metre swim

Effect of caffeinated drinks on substrate metabolism, caffeine excretion, and performance

The effect of addition of different dosages of caffeine (Caf) to a carbohydrate-electrolyte solution (CES) on metabolism, Caf excretion, and performance was examined. Subjects (n = 15) ingested 8 ml/kg of water placebo (Pla-W), 7% CES (Pla-CES), or 7% CES with 150, 225, and 320 mg/l Caf (CES-150, CES-225, and CES-320, respectively) during a warm-up protocol (20 min) and 3 ml/kg at one-third and two-thirds of a 1-h time trial. Performance was improved with Caf supplementation: 62.5 +/- 1.3, 61.5 +/- 1.1, 60.4 +/- 1.0, 58.9 +/- 1.0, and 58.9 +/- 1.2 min for Pla-W, Pla-CES, CES-150, CES-225, and CES-320, respectively. The postexercise urinary Caf concentration (range 1.3-2.5 microg/ml) was dose dependent and always far below the doping level of the International Olympic Committee (12 microg/ml) in all subjects. Sweat Caf excretion during exercise exceeded postexercise early-void urinary Caf excretion. Caffeinated CES did not enhance free fatty acid availability, ruling out the fact that performance improvement resulted from enhanced fat oxidation. It is concluded that addition of relatively low amounts of Caf to CES improves performance and that postexercise urinary Caf concentration remained low.

Caffeine toxicity in a bodybuilder

Substance abuse is well documented among bodybuilders and weight lifters keen to enhance their performance. A case is described of abuse of caffeine to toxic levels by an amateur bodybuilder and is believed to be the first documented case of such recreational abuse.

Nutrition for improved sports performance. Current issues on ergogenic aids

Several nutritional modifications have been used by athletes to improve performance. Recent attention has focused on high fat diets, branched-chain amino acids, creatine, carnitine, bicarbonate and phosphate loading, and caffeine. Of these, only caffeine, which is present in food but has no known nutritional value, appears on the list of substances banned by the International Olympic Committee (IOC). While there is a theoretical basis for each of these diet manipulations to enhance performance, there are insufficient data to state unequivocally that high fat diets, branched-chain amino acids, carnitine or phosphate loading are effective. Caffeine has been found to enhance endurance performance, while creatine and bicarbonate loading were generally found to benefit short term strenuous exercise. Acute ingestion of these diet manipulations appears safe, although some, like caffeine and bicarbonate, can cause gastrointestinal disturbances or other problems in certain individuals. Long term use of high fat diets may have negative consequences on health. The safety of long term use of these diet manipulations has not been established.