Abstract

The aim of this study was to assess the effect of caffeine ingestion on 8km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3mg kg71 body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8km performance time (P50.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI]¼13.1 to 34.5 s) in 8km performance time (1.2% improvement, 95% CI¼0.7 to 1.8%). In addition, a two-way (time6condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3min after exercise during the caffeine trial (P50.05). We conclude that ingestion of 3mg kg71 body mass of caffeine can improve absolute 8km run performance in an ecologically valid race setting. Verf.-Referat