RESUMO
PURPOSE: The purpose of this study was to determine whether caffeine gum improves the performance of recreational runners completing parkruns (weekly, 5 km, mass participant running events). METHODS: Thirty-six recreational runners (M = 31, F = 5; age 33.7 ± 10.7 y; BMI 23.1 ± 2.4 kg/m2) capable of running 5 km in < 25 min were recruited to a study at the Sheffield Hallam parkrun, UK. Runners were block randomized into one of three double-blind, placebo-controlled, cross-over intervention trials with caffeine gum as the treatment (n = 6 per intervention trial) or into one of three non-intervention trials that ran concurrently with the intervention trials (n = 6 per non-intervention trial). Changes in conditions across different parkruns were adjusted for using data from the non-intervention trials. Runners in the randomized cross-over intervention trials chewed gum supplying 300 mg of caffeine or a placebo gum for 5 min, starting 30 min before each parkrun. RESULTS: Caffeine gum improved 5 km parkrun performance by a mean of 17.28 s (95% CI 4.19, 30.37; P = 0.01). Adjustment for environmental conditions using data from the non-intervention trials attenuated the statistical significance (P = 0.04). Caffeine gum also decreased RPE by 1.21 (95% CI 0.30, 2.13; P = 0·01) units relative to placebo. CONCLUSIONS: A 300 mg dose of caffeine supplied in chewing gum improved the performance of recreational runners completing 5 km parkruns by an average of 17 s. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov: NCT02473575 before recruitment commenced.