Key words: METHYLXANTHINES, REPEATED SPRINT ABILITY, INTERMITTENT EXERCISE, ERGOGENIC, FATIGUE

Purpose: The aim of this study was to examine the effects of caffeine supplementation on multiple sprint running performance. Methods: Using a randomised double-blind research design, 21 physically active men ingested a gelatine capsule containing either caffeine (5 mgkg body mass -1 ) or placebo (maltodextrin) one hour before completing an indoor multiple sprint running trial (12  30 m; repeated at 35 s intervals). Venous blood samples were drawn to evaluate plasma caffeine and primary metabolite concentrations. Sprint times were recorded via twin-beam photocells and earlobe blood samples were drawn to evaluate pre and post-test lactate concentrations. Heart rate was monitored continuously throughout the tests with ratings of perceived exertion (RPE) recorded after every third sprint. Results: Relative to placebo, caffeine supplementation resulted in a 0.06 s (1.4%) reduction in fastest sprint time (95% likely range: 0.04 to 0.09 s), which corresponded with a 1.2% increase in fatigue (95% likely range: 0.3 to 2.2%). Caffeine supplementation also resulted in a 3.4 bmin -1 increase in mean heart rate (95% likely range: 0.1 to 6.6 bmin -1 ), and elevations in pre (+ 0.7 mmolL -1 ; 95% likely range: 0.1 to 1.3 mmolL -1 ) and post-test (+ 1.8 mmolL -1 ; 95% likely range: 0.3 to 3.2 mmolL -1 ) blood lactate concentrations. In contrast, there was no significant effect of caffeine supplementation on RPE. Conclusion: Although the effect of recovery duration on caffeine-induced responses to multiple sprint work requires further investigation, the results of the present study show that caffeine has ergogenic properties with the potential to benefit performance in both single and multiple sprint sports.