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Dietary nitrate does not enhance running performance in elite cross-country skiers.

Medicine and science in sports and exercise (2012-08-10)
Oliver Peacock, Arnt Erik Tjønna, Philip James, Ulrik Wisløff, Boye Welde, Nikolai Böhlke, Alan Smith, Keith Stokes, Christian Cook, Oyvind Sandbakk
ABSTRACT

The objective of this study is to examine the effects of acute ingestion of dietary nitrate on endurance running performance in highly trained cross-country skiers. Dietary nitrate has been shown to reduce the oxygen cost of submaximal exercise and improve tolerance of high-intensity exercise, but it is not known if this holds true for highly trained endurance athletes. Ten male junior cross-country skiers (V˙O(2max)) ≈ 70 mL·kg·min) each completed two trials in a randomized, double-blind design. Participants ingested potassium nitrate (614-mg nitrate) or a nitrate-free placebo 2.5 h before two 5-min submaximal tests on a treadmill at 10 km·h (≈55% of V˙O(2max)) and 14 km·h (≈75% of V˙O(2max)), followed by a 5-km running time trial on an indoor track. Plasma nitrite concentrations were higher after nitrate supplementation (325 ± 95 nmol·L) compared with placebo (143 ± 59 nmol·L, P < 0.001). There was no significant difference in 5-km time-trial performance between nitrate (1005 ± 53 s) and placebo treatments (996 ± 49 s, P = 0.12). The oxygen cost of submaximal running was not significantly different between placebo and nitrate trials at 10 km·h (both 2.84 ± 0.34 L·min) and 14 km·h (3.89 ± 0.39 vs. 3.77 ± 0.62 L·min). Acute ingestion of dietary nitrate may not represent an effective strategy for reducing the oxygen cost of submaximal exercise or for enhancing endurance exercise performance in highly trained cross-country skiers.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Potassium nitrate, 99.99% trace metals basis
Supelco
Nitrate ion standard solution, 0.01 M NO3-, for ion-selective electrodes
Sigma-Aldrich
Potassium nitrate, 99.999% trace metals basis
Sigma-Aldrich
Potassium nitrate, BioReagent, suitable for cell culture, suitable for plant cell culture
Sigma-Aldrich
Potassium nitrate, BioXtra, ≥99.0%
Sigma-Aldrich
Potassium nitrate, ReagentPlus®, ≥99.0%
Sigma-Aldrich
Potassium nitrate, puriss., meets analytical specification of Ph Eur, BP, USP, FCC, E252, 99.0-100.5%
Sigma-Aldrich
Potassium nitrate, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99%
Sigma-Aldrich
Potassium nitrate, ACS reagent, ≥99.0%
Supelco
Mettler-Toledo Calibration substance ME 51143095, Potassium nitrate, traceable to primary standards (LGC)