Lowings, S, Shannon, OM, Deighton, K et al. (2 more authors) (2017) Effect of Dietary Nitrate Supplementation on Swimming Performance in Trained Swimmers. International Journal of Sport Nutrition and Exercise Metabolism, 27 (4). pp. 377-384. ISSN 1526-484X
Abstract
Nitrate supplementation appears to be most ergogenic when oxygen availability is restricted and subsequently may be particularly beneficial for swimming performance due to the breath-hold element of this sport. This represents the first investigation of nitrate supplementation and swimming time-trial (TT) performance. In a randomized double-blind repeated-measures crossover study, ten (5 male, 5 female) trained swimmers ingested 140ml nitrate-rich (~12.5mmol nitrate) or nitrate-depleted (~0.01mmol nitrate) beetroot juice. Three hours later, subjects completed a maximal effort swim TT comprising 168m (8 × 21m lengths) backstroke. Preexercise fractional exhaled nitric oxide concentration was significantly elevated with nitrate compared with placebo, Mean (SD): 17 (9) vs. 7 (3)p.p.b., p = .008. Nitrate supplementation had a likely trivial effect on overall swim TT performance (mean difference 1.22s; 90% CI -0.18–2.6s; 0.93%; p = .144; d = 0.13; unlikely beneficial (22.6%), likely trivial (77.2%), most unlikely negative (0.2%)). The effects of nitrate supplementation during the first half of the TT were trivial (mean difference 0.29s; 90% CI -0.94–1.5s; 0.46%; p = .678; d = 0.05), but there was a possible beneficial effect of nitrate supplementation during the second half of the TT (mean difference 0.93s; 90% CI 0.13–1.70s; 1.36%; p = .062; d = 0.24; possibly beneficial (63.5%), possibly trivial (36.3%), most unlikely negative (0.2%)). The duration and speed of underwater swimming within the performance did not differ between nitrate and placebo (both p > .30). Nitrate supplementation increased nitric oxide bioavailability but did not benefit short-distance swimming performance or the underwater phases of the TT. Further investigation into the effects of nitrate supplementation during the second half of performance tests may be warranted.
Metadata
Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Human Kinetics, Inc. This is an accepted author manuscript version reprinted, by permission, from International Journal of Sport Nutrition and Exercise Metabolism, 2017, 27 (4): 377-384, https://doi.org/10.1123/ijsnem.2016-0251. |
Keywords: | beetroot, exercise performance, time trial, ergogenic aid |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Leeds Institute of Health Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 27 Mar 2018 11:55 |
Last Modified: | 27 Mar 2018 11:55 |
Status: | Published |
Publisher: | Human Kinetics |
Identification Number: | https://doi.org/10.1123/ijsnem.2016-0251 |