Porcelli, S., Pugliese, L., Rejc, E., Pavei, G., Bonato, M., La Torre, A., Marzorati, M., & Marconi, C. (2012). Did Popeyeİ know something about nitrates? Presentation 1823 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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This study investigated if nitrates supplementation enhances muscle strength and anaerobic performance. Males (N = 7) were tested before and after six days of 0.5 l/day spinach juice (5.5 mol/day nitrates or placebo. Tests were a) maximal voluntary isometric contraction of knee extensors; b) fatiguing, intermittent sub-maximal (75% MVC) isometric knee extensions; c) Wingate 30s test; and d) Repeated Sprint Ability Test (RSA) comprising one set of 5 × 6-secs maximal sprints with 24 seconds of passive recovery between repetitions. During the isometric exercises, the EMGs of the vastus lateralis and biceps femoris were recorded. Blood lactate was obtained at rest and after exercise on a mechanically braked cycle ergometer.

The placebo condition produced no significant differences. In the spinach juice versus placebo comparisons: a) Maximal voluntary torque of knee extensors was not significantly different; total muscle work, estimated as the sum of impulses generated during the fatiguing sub-maximal contractions, was significantly higher in the spinach juice condition; and b) during the Wingate test, mean power was significantly higher and the fatigue index was significantly lower in the spinach-juice group. Peak lactate was not significantly different. In the Repeated Sprint Ability Test, peak power was significantly higher during the 3rd, 4th and 5th repetitions.

Implication. A moderate dietary dose of nitrates (spinach juice) significantly enhances variables of anaerobic performance.

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