Effects of Dietary Nitrate, Caffeine, and Their Combination on 20-km Cycling Time Trial Performance

Abstract

The aim of this study was to examine the acute supplementation effects of dietary nitrate, caffeine, and their combination on 20 km cycling time-trial performance. Using a randomized, counterbalanced, double-blind, Latin-square design, 14 competitive, female cyclists (age: 31  7 years; height: 1.69  0.07 m; body mass: 61.6  6.0 kg) completed four 20 km time-trials on a racing bicycle fitted to a turbo-trainer. 2.5 hours before each trial, subjects consumed a 70 ml dose of concentrated beetroot juice containing either 0.45 g of dietary nitrate, or with the nitrate content removed (placebo). 1 hour before each trial, subjects consumed a capsule containing either 5 mgkg There were no effects (p ≥ 0.05) of supplementation on cycling cadence, ratings of perceived exertion, V O 2 , or integrated electromyographic activity. The results of this study support the well-established beneficial effects of caffeine supplementation on endurance performance. In contrast, acute supplementation with dietary nitrate appears to have no effect on endurance performance and adds nothing to the benefits afforded by caffeine supplementation.

Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

“…This may be explained by the elevated baseline plasma [NO 3 − ] and [NO 2 − ] in this cohort (Vassalle et al 2003), although multiple other factors may also be important (Jones 2014). It is therefore unclear whether the reduced effects of NO 3 − supplementation reported during longer vs. shorter duration exercise tests are related to the exercise duration (and requisite work rate) or the high training status of subjects in these investigations (Bescós et al 2012;Wilkerson et al 2012;Cermak et al 2012b;Lane et al 2014;Glaister et al 2015). Direct comparison between the effects of NO 3 − supplementation on short and longer duration (< or >30 min) exercise performance where other methodological variables are fixed is necessary, yet presently scarce.…”

“…Notably, Lansley et al (2011) reported a significant and comparable improvement in 4 km (TT duration: ~6 min; performance improvement: 2.8%) and 16.1 km (TT duration: ~ 28 min; performance improvement: 2.7%) cycle ergometry TT performance in moderately trained males (VO 2max ~56 ml kg −1 min −1 ) consequent to NO 3 − ingestion. Conversely, NO 3 − supplementation has been reported to have a minimal effect on performance during longer duration (>30 min) exercise tests, which mandate a lower work rate (Bescós et al 2012;Wilkerson et al 2012;Cermak et al 2012b;Lane et al 2014;Glaister et al 2015).…”

The Effect of Ergogenic Supplements and Mediterranean Diet on Cycling Performance. Differences According to Duration and Intensity.

“…There are many studies suggesting that caffeine improves power and endurance compared to placebo or other supplements [26,29,35,54,57,81]. A moderate dose of caffeine significantly improves performance DOI 10.18502/ajne.v2i1.1242…”

Potential Benefits of Caffeine Alone or in Combination with Nitrate Supplementation in Blood Pressure Control in the Elderly

“…23 NO action peak occurs, on average, between two to three hours after inorganic nitrate consumption. 24,25 Inorganic nitrate consumption may promote a 2.5 to 6.4mmHg decrease in systolic BP and a 0.4 to 3.0mmHg decrease in diastolic BP. 26 Inorganic nitrate peak effect on BP occurs 2.5-3 hours following ingestion (coinciding with nitrite plasma levels) and its half-life is between 5 and 8 h. 20 Although there are few studies which approach inorganic nitrate supplementation for the elderly population, the results are positive regarding BP control (or its decrease), using dietary sources of nitrate.…”

“…24,25 Inorganic nitrate consumption may promote a 2.5 to 6.4mmHg decrease in systolic BP and a 0.4 to 3.0mmHg decrease in diastolic BP. 26 Inorganic nitrate peak effect on BP occurs 2.5-3 hours following ingestion (coinciding with nitrite plasma levels) and its half-life is between 5 and 8 h.…”