Caffeine intake improves time to exhaustion in runners – meta-analysis

Caffeine is a common ingredient used in sports nutrition, with companies using it as a sports nutrition ingredient for endurance and strength training​.

Writing in Nutrients, ​researchers from Beijing Sport University and Rey Juan Carlos University studied 21 randomised placebo-controlled trials involving 254 participants for this particular meta-analysis.

These studies were sieved out from Medline, Scopus, Web of Science, and SportDiscus and were published as of October last year.  

Out of the 21 studies, 18 provided caffeine in liquid or capsule form, with doses normalised by participants’ body mass, which were between three and nine mg/kg.

The other three studies provided absolute doses of caffeine in the form of caffeine powder, gum, and oral strips, with doses ranging from 200 to 300 mg.

Two-thirds of the trials also studied the effects of caffeine in time trial runs, while the remaining ones looked at caffeine’s effects on time-to-exhaustion runs.

Between the two, time trials offer a better scenario to study the effect of caffeine on endurance running performance, as runners’ performance is more reproducible in time-trial runs than in running to exhaustion events, the researchers said.

Effects on runners

Caffeine intake has shown to prolong the time to exhaustion as compared with the placebo in both recreational runners and trained runners.  

Among the intervention groups, caffeine intake has overall increased time to exhaustion by 16.97 ± 14.65 per cent.  

“Caffeine promotes the production of ß-endorphins and dopamine, which can lessen perceived effort and discomfort.