Loading phase increases performance improvement by nitrates
Athletes who take a portion of nitrates 2-3 hours before training or competition - in the form of spinach, beetroot or potassium nitrate - perform better. The same athletes will perform even better if they take such a dose of nitrates every day for 2 weeks. Researchers from California State Polytechnic University come to this conclusion in a human study, published in the Journal of Strength and Conditioning Research.
The researchers divided 29 recreational athletes aged 18-29 into 2 groups. Both groups rode a time trial of 8 kilometers, and did this again after 15 days.
One group took a placebo every day during the experiment. On the last day, 2 hours before the time trial, the athletes received a supplement with "100 mg or vitamin C, 200 mg or magnesium, and a 1,300 mg blend or potassium nitrate, quercetin, beet powder, grape extract, and spinach powder". The supplement contained half a gram of nitrate. That's the same as 8 millimoles.
The other group took the supplement itself every day during the experiment. The test subjects in this group also received a supplement on the last day, 2 hours before they rode the time trial.
The researchers used a product from the the American company Shaklee. [shaklee.com] Shaklee does not market this product as a sports supplement, but as a blood pressure reducer. Shaklee did not sponsor the study.
After the one-time intake of nitrates, the test subjects completed the 8-kilometer time trial 0.4 minutes faster than before. However, that difference was not statistically significant.
The subjects who had taken extra nitrates for 15 days did become significantly faster. The supplementation with nitrates made them a full minute faster.
"On the basis of the current findings, 15 days of nitrate supplementation at 8 mmol (500 mg) per day may enhance relatively high intensity cycling performance in recreationally trained individuals", write the researchers.
"Collectively, long-term dietary nitrate intake, whether through food or supplementation, represents a promising and novel ergogenic strategy although optimum procedures and conditions have yet to be precisely identified."
J Strength Cond Res. 2019 Jan;33(1):217-24.
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