No Differences Between Beetroot Juice and Placebo on Competitive 5-km Running Performance: A Double-Blind, Placebo-Controlled Trial

Philip Hurst ^[1] ; Samantha Saunders ^[2] ; Damian Coleman ^[1]
1. [1] Canterbury Christ Church University
  
  Canterbury Christ Church University
  
  City of Canterbury, Reino Unido
2. [2] Defence Science and Technology Laboratory DSTL. Salisbury, Reino Unido
Localización: International journal of sport nutrition and exercise metabolism, ISSN 1526-484X, ISSN-e 1543-2742, Vol. 30, Nº. 4, 2020, págs. 295-300
Idioma: inglés
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Resumen
- The authors examine the effect of an acute dose of beetroot juice on endurance running performance in “real-world” competitive settings. In total, 70 recreational runners (mean ± SD: age = 33.3 ± 12.3 years, training history = 11.9 ± 8.1 years, and hours per week training = 5.9 ± 3.5) completed a quasi-randomized, double-blind, placebo-controlled study of 5-km competitive time trials. Participants performed four trials separated by 1 week in the order of prebaseline, two experimental, and one postbaseline. 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 hr prior to time trials. Time to complete 5 km was recorded for each trial. No differences were shown between pre- and postbaseline (p = .128, coefficient variation = 2.66%). The average of these two trials is therefore used as baseline. Compared with baseline, participants ran faster with beetroot juice (mean differences = 22.2 ± 5.0 s, p < .001, d = 0.08) and placebo (22.9 ± 4.5 s, p < .001, d = 0.09). No differences in times were shown between beetroot juice and placebo (0.8 ± 5.7 s, p < .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 with placebo.