Caffeine has a small effect on 5-km running performance of well-trained and recreational runners.

The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners. Using a double-blind placebo-controlled design, 15 well-trained and 15 recreational runners completed two randomized 5-km time-trials, after ingestion of either 5mgkg(-1) of caffeine or a placebo. Caffeine ingestion significantly improved 5-km running performance in both the well-trained and recreational runners.