No Effect of Beetroot Juice Supplementation on 100-m and 200-m Swimming Performance in Moderately-Trained Swimmers.

Abstract

Dietary nitrate supplementation has been reported to improve performance in kayaking and rowing exercise which mandate significant recruitment of the upper body musculature. Since the effect of dietary nitrate supplementation on swimming performance is unclear, the purpose of this study was to assess the effect of dietary nitrate supplementation on 100-m and 200-m swimming freestyle time-trial (TT) performance. In a double blind, randomized crossover design, ten moderately-trained swimmers underwent two separate 3-day supplementation periods, with a daily dose of either 140 mL nitrate-rich (BRJ; ~800 mg/d nitrate) or nitrate-depleted (PLA) BRJ. Following blood sampling on day 3, the swimmers performed both 200-m and 100-m freestyle swimming TTs, with 30 min recovery between trials. Plasma nitrite concentrations was greater after BRJ relative to PLA consumption (432 ± 203 nmol/L, 111 ± 56 nmol/L, respectively, p = 0.001). Systolic BP was lowered after BRJ compared to PLA supplementation (114 ± 10, 120 ± 10 mmHg, respectively p = 0.001), but time to complete the 200-m (BRJ: 152.6 ± 14.1 s, PLA: 152.5 ± 14.1 s) and 100-m (BRJ: 69.5 ± 7.2 s, PLA: 69.4 ± 7.4 s) freestyle swimming TTs were not different between BRJ and PLA (p > 0.05). While 3 days of BRJ supplementation increased plasma nitrite concentration and lowered blood pressure, it did not improve 100-m and 200-m swimming TT performance. These results do not support an ergogenic effect of nitrate supplementation in moderately-trained swimmers, at least for 100-m and 200-m freestyle swimming performance.