Now caffeine's legal�

The International Association of Athletics Federations (IAAF) has removed caffeine from its list of banned substances, and athletes can now swig coke and coffee to their hearts' content before key events. But will it enhance their performance? And are there any drawbacks?

Key points

1. There is plenty of evidence to suggest that caffeine offers a helpful boost to endurance performance;
2. By contrast, evidence for the effects of caffeine ingestion on sprint and power performance is limited and inconclusive;
3. Athletes who normally avoid caffeine may experience adverse effects � including anxiety, gastrointestinal disturbances, restlessness, insomnia and even heart arrhythmias � if they start using it as an ergogenic aid;
4. Conversely, those who use caffeine regularly may experience a �tolerance effect' and may need to shun caffeine in all its forms for a few days before an event to experience an ergogenic effect from supplementation;
5. Dosages higher than 5mg per kg of body mass do not elicit any greater performance effects and tend to raise the risk of unwanted side effects.