The effect of six days of dietary nitrate supplementation on performance in trained CrossFit athletes

Abstract

BackgroundWhile it is well established that dietary nitrate reduces the metabolic cost of exercise, recent evidence suggests this effect is maintained 24 h following the final nitrate dose when plasma nitrite levels have returned to baseline. In addition, acute dietary nitrate was recently reported to enhance peak power production. Our purpose was to examine whether chronic dietary nitrate supplementation enhanced peak power 24 h following the final dose and if this impacted performance in a heavily power-dependent sport.MethodsIn a double-blind, randomized, crossover design, maximal aerobic capacity, body composition, strength, maximal power (30 s Wingate), endurance (2 km rowing time trial), and CrossFit performance (Grace protocol) were assessed before and after six days of supplementation with nitrate (NO) (8 mmol·potassium nitrate·d−1) or a non-caloric placebo (PL). A 10-day washout period divided treatment conditions. Paired t-tests were utilized to assess changes over time and to compare changes between treatments.ResultsPeak Wingate power increased significantly over time with NO (889.17 ± 179.69 W to 948.08 ± 186.80 W; p = 0.01) but not PL (898.08 ± 183.24 W to 905.00 ± 157.23 W; p = 0.75). However, CrossFit performance was unchanged, and there were no changes in any other performance parameters.ConclusionConsuming dietary nitrate in the potassium nitrate salt form improved peak power during a Wingate test, but did not improve elements of strength or endurance in male CrossFit athletes.

Effects of Natural Nutritional Beverages on Anaerobic Exercise Performance

“…To compare the performance changes between the 30-s and 60-s tests, the percent change (∆) between the experimental and placebo supplements was calculated for the 30- In contrast to the findings of this study, Kramer et al, (2016) found an increase in peak power during a 30-s Wingate from pre-to post-supplementation with 8 mmol•day -1 potassium NO3-. Some key differences should be noted when comparing the present study to Kramer et al's (2016) work.…”

“…Peak power during a Wingate cycling test improved with 8 mmol KNO3 supplementation versus a control (948.08 ± 186.80 W vs. 889.17 ±179.69 W), with no differences in mean power (Kramer et al, 2016). These results suggest that not only can dietary NO3-possible enhance peak power, but it can be effective if taken 24 hours or more prior to an event.…”

“…Improvements have been seen during both aerobic and anaerobic exercise, but NO3-'s effects on the oxygen cost of exercise and exercise tolerance during aerobic work have been the focus of most of the research in this area. Current evidence suggests that shorter bouts of mostly anaerobic type activity may improve with NO3-supplementation, but the research in this area is scarce (Kramer et al, 2016;Rimer et al, 2015). As suggested by some, dietary NO3-'s ability to produce performance benefits during short duration, high power activity may be mechanistically different than the benefits yielded from NO3-supplementation with aerobic exercise (Thompson et al, 2015).…”

“…Recent studies have focused more specifically on isolated bouts of anaerobic activity, yielding preliminary evidence that NO3-supplementation can produce performance benefits during this type of exercise (Kramer et al, 2016;Rimer et al, 2015). Rimer et al (2015) examined the role of an acute dose of ~11.2 mmol of NO3-(beet juice) on maximal power (Pmax) and optimal pedaling (RPMoptimal) rate during short bouts (3-4 s) of maximal effort cycling.…”

“…A review of the evidence suggests that NO3-supplementation may improve anaerobic performance by increasing peak power output Kramer, Baur, Spicer, Vukovich & Ormsbee, 2016;Larsen et al, 2007;Rimer, Peterson, Coggan & Martin, 2015). Dietary NO3-'s effects on the 30-s Wingate test, specifically utilizing beets as the NO3-source, has not been studied.…”