Dietary Nitrate Does Not Enhance Running Performance in Elite Cross-Country Skiers

PEACOCK, O., A. E. TJONNA, P. JAMES, U. WISLOFF, B. WELDE, N. BOHLKE, A. SMITH, K. STOKES, C. COOK, and O. SANDBAKK. Dietary Nitrate Does Not Enhance Running Performance in Elite Cross-Country Skiers. Med. Sci. Sports Exerc., Vol. 44, No. 11, pp. 2213-2219, 2012. Purpose: 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. Methods: Ten male junior cross-country skiers (V (over dot)O-2max approximate to 70 mL.kg(-1).min(-1)) 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(-1) (approximate to 55% of V (over dot)O-2max and 14 kmh(-1) (approximate to 75% of V (over dot)O-2max), followed by a 5-km running time trial on an indoor track. Results: Plasma nitrite concentrations were higher afler nitrate supplementation (325 +/- 95 nmol.L-1) compared with placebo (143 +/- 59 nmol.L-1, 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(-1) (both 2.84 +/- 0.34 L.min(-1)) and 14 km.h(-1) (3.89 +/- 0.39 vs. 3.77 +/- 0.62 L.min(-1)). Conclusions: 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.