No differences between beetroot juice and placebo on competitive 5-km running performance: A double-blind, placebo-controlled trial

We examined the effect of beetroot juice on endurance running performance in “real-world” competitive settings. One-hundred recreational runners (54% male; mean ± standard deviation, age = 33.3 ± 12.3 years, training history = 11.9 ± 8.1 years, hours per week training = 5.9 ± 3.5) completed a quasi-randomised, double-blind, placebo-controlled study of 5-km competitive time-trials. Participants performed four trials separated by one week in the order of pre-baseline, two experimental, and one post-baseline. Experimental trials consisted of the administration of 70-mL nitrate rich beetroot juice (containing ~4.1 mmol of nitrate, Beet It Sport®) or nitrate depleted placebo (containing ~0.04 mmol of nitrate, Beet It Sport®) 2.5 hours prior to time-trials. Time to complete 5-km was recorded for each trial. No differences were shown between pre- and post-baseline (P = 0.128, CV = 2.66%). The average of these two trials is therefore used as baseline. Compared to baseline, participants ran faster with beetroot juice (mean differences = 22.2 ± 5.0 s, P < 0.001, d = 0.08) and placebo (22.9 ± 4.5 s, P < 0.001, d = 0.09). No differences in times were shown between beetroot juice or placebo (0.8 ± 5.7 s, P < 0.875, d = 0.00). These results indicate that an acute dose of beetroot juice does not improve competitive 5-km time-trial performance in recreational runners compared to placebo.