There are a large number of products available which claim to help sports performance in some way. These are known as ergogenic aids. The range of nutritional substances used as ergogenic aids in sport is huge and includes amino acid supplements, ginseng and bee pollen.
For many of these supplements there is little scientific evidence for their effectiveness. Moreover, undesirable side-effects can occur and the implications for long-term health have not been fully tested. Ergogenic aids are not a substitute for a healthy, balanced diet, regular training and adequate rest.
Two ergogenic aids which have received much research attention in recent years are caffeine and creatine.
Creatine has been of particular interest as an ergogenic aid because of the role that creatine phosphate plays in energy production. During the first few seconds of exercise creatine phosphate is broken down to produce ATP. This is an extremely fast method of energy production yet the muscle only has very limited creatine stores. The use of creatine supplements attempts to maximise muscle stores and thereby enhance energy production. Results to date are equivocal but are most supportive of a beneficial effect of creatine in events involving bouts of high intensity exercise with only short recovery periods in between, such as football. There have been no studies on the long-term safety of creatine.
There is evidence for a positive effect of caffeine on performance during prolonged endurance events. The ergogenic effect may be related to its stimulant properties, particularly to the effect of caffeine in mobilising fatty acids, which can then be used as a fuel, sparing glycogen stores (see above). A caffeine level in the urine above 12mg/l is not permitted under international doping regulations (a level achieved by taking approximately 500mg caffeine, equivalent to 6-8 cups of coffee, in a single sitting). However, ergogenic effects are produced at lower levels than this.