Team sport athletes should not expect caffeine to enhance their sprint performance: that's the conclusion of a New Zealand study comparing the effects of caffeine and placebo on performance in a test designed to simulate the repeated brief sprints of team sports.

While numerous studies have established that caffeine improves endurance performance, there have been few studies of its effects on short-term performance. Those which have been done suggest that caffeine produces an enhanced performance of a single 30secs sprint that would be worthwhile for a track-and-field athlete.

However, when fatigue develops during repeated sprints, caffeine appears to make it worse. Repeated sprints are the norm in team and court sports, but each sprint generally lasts only a few seconds and the effect of caffeine on such sprints is therefore unclear.

In this double-blind study, 16 male sport-science students, all competitive team-sport athletes in basketball, hockey or rugby, were tested in a temperature-controlled gym on two occasions 2-3 days apart. Sixty minutes before each test each subject ingested a capsule containing either caffeine or a glucose placebo in a dose of 6mg/kg of body mass.

The test consisted of 10 20m sprints, each completed within 10 seconds, followed by a rest for the remainder of the 10 seconds.

The results were as follows:

l. In comparison with placebo, ingestion of caffeine resulted in a 0.1% increase in mean time to complete the 10 sprints, although individual variation ranged from a 2.7% decrease to a 2.9% increase.

2. Fatigue was apparent as an increase in time for each sprint. But while the increase in time over the 10 sprints was 14% with placebo, it was 0.7% higher with caffeine.

'Neither of these effects was large enough to be of any practical significance for a team-sport player,' comment the authors, 'but the confidence limits allow for the possibility that the true effect on mean performance could be small and beneficial or small and harmful. The true effect on fatigue could also be small and beneficial, but there is more likelihood of a larger harmful effect.'

'Further research with a larger sample, more trials or a more reliable performance measure would give more precise estimates of these effects.'
'In conclusion, the observed effects of caffeine on mean sprint performance and on fatigue over 10 sprints were negligible for the average team-sport athlete and the true effects are unlikely to be anything more than small.'
Med Sci Sports Exerc 2001 May 33(5) p822-5

Isabel Walker