Central nervous system stimulants and sport practice

Central nervous system (CNS) stimulants were originally used by athletes to improve performance on the day of competition. Although there was evidence that these drugs might be linked with sudden collapse or death, usually from cardiac or respiratory arrest, particularly during competition, the long term side effects of addiction and physiological damage to the body were regarded as minor or were not mentioned.). These substances are either prohibited or monitored, previously by the International Olympic Committee (IOC) and now by the World Anti-Doping Agency (WADA), and are screened for daily by accredited laboratories (table 1).

Table 1 Annual statistics for drug testing by IOC accredited laboratories

*Data from WADA, [dagger]data from IOC.

Year	Total A samples analysed	Number of positive samples with stimulants	% Positive samples with stimulants
2004*	169187	382	0.23
2003*	151210	516	0.35
2002[dagger]	131373	392	0.30
2001[dagger]	125701	352	0.28
2000[dagger]	117314	453	0.39
1999[dagger]	118243	532	0.45
1998[dagger]	105250	412	0.39
1997[dagger]	106561	356	0.33
1996[dagger]	96454	281	0.29
1995[dagger]	93938	310	0.33
1994[dagger]	93680	347	0.37
1993[dagger]	89166	331	0.37
1992[dagger]	87808	277	0.32
1991[dagger]	84088	221	0.26
1990[dagger]	71941	340	0.47
1989[dagger]	52371	508	0.97
1988*	47069	420	0.89

Chemical structure of amfetamine, ephedrine, and cocaine.

Caffeine is the pharmacologically active substance found in tea, coffee, and cola. The amount of caffeine present varies according to the type of drink and the way it has been prepared. Caffeine may also be a constituent of some common medicines such as cold preparations and pain relief treatments, usually in quantities of less than 100 mg per dose. Caffeine produces mild CNS stimulation, similar to that of amfetamines, reducing fatigue and increasing concentration and alertness. Physiological effects include increased heart rate and output, metabolic rate, and urine production. High doses can cause anxiety, insomnia, and nervousness. In 2004 caffeine was removed from the list of prohibited substances and is now part of the monitoring programme.

Amfetamines are controlled substances under general drugs legislation, although they have been prescribed as appetite suppressants and for the treatment of narcolepsy. They are known to produce dependence, often in increasing doses. Athletes are likely to use amfetamines to sharpen reflexes and reduce tiredness. However, athletes have died as a result of amfetamine misuse, since the...