Purpose: This study investigated the effects of chronic 3-day beetroot juice (BRJ) supplementation on maximum oxygen uptake (VO2max), velocity associated with VO2max(vVO2max), and peak velocity (Vpeak) in recreational runners.
Methods: Thirteen male recreational runners (age 28.2 ± 3.0 years, height 176.8 ± 0.1 cm, body mass 74.4 ± 9.5 kg) performed four tests on a treadmill in a randomized, double-blind, crossover design: two maximum incremental tests to determine VO2max and vVO2max, and two tests to determine Vpeak. Trials were performed following 3 days of supplementation of NO3--rich BRJ in natura (8.4 mmol NO3- day- 1) or BRJ NO3--depleted placebo (0.01 mmol NO3- day- 1), with the last dose being ingested 2 h before each test. During the tests, maximum heart rate (HRmax), maximal rating of perceived exertion (RPEmax), pre- and post-test glucose concentrations (Glucpre, Glucpost), and peak blood lactate concentration were determined.
Results: VO2max was higher following BRJ vs PLA (46.6 ± 6.4 vs 45.1 ± 5.8 mL kg- 1 min- 1; P = 0.022), as well as vVO2max (14.5 ± 0.8 vs 13.9 ± 1.0 km h- 1P = 0.024) and Vpeak (15.5 ± 1.1 vs 15.2 ± 1.2 km h- 1P = 0.038), with no differences in the other variables.
Conclusion: Consumption of NO3--rich BRJ in natura (8.4 mmol NO3- day- 1) once per day for 3 days improved VO2max, vVO2max and Vpeak in recreational runners without changing the other analyzed variables.
Keywords: Exercise nutritional science; Nitrate supplementation; Nitric oxide; Physical endurance; Running.