In recent years elite Tour de France cyclists began supplementing with high dosages of concentrated beet root juices for the plant's endurance-enhancing effects. The reason for this is that beets contain nitrate, which gets converted to nitric oxide in the body. Nitric oxide causes vasodilation which increases blood flow. Increased blood flow results in a more efficient delivery of oxygen and nutrients to working skeletal muscles for improved performance.
A recent study wanted to observe if consuming a short-term high-nitrate diet could increase nitric oxide bio availability and performance. Find out what foods you need to eat to follow a high-nitrate diet and how to nitrate load similarly to the study to enhance exercise performance.
Seven male subjects participated in a randomized crossover study. They were tested before and after a six-day high-nitrate diet and a control nitrate diet (8.2 mmol per day vs 2.9 mmol per day, respectively). Plasma nitrate and nitrite concentrations were significantly higher in the high-nitrate diet group compared to the control group. The high-nitrate group also showed a significant reduction of oxygen consumption during moderate-intensity constant work rate cycling, a significantly higher total muscle work during fatiguing intermittent sub-maximal knee extension. and improved performance in repeated sprint ability test.
The findings from the study provide a feasible and effective strategy to improve exercise performance. A short-term, high-nitrate diet was able to reduce oxygen consumption during moderate-intensity exercise (improved endurance), increase work load during resistance training (muscular endurance) and improve repeat sprint ability. For team sport athletes these are all attributes that are highly correlated to success.
For athletes looking to implement nitrates into their diet prior to competition some quality sources include:
- Arugula (or Rucola or Rocket)
- Bok Choy
One thing to consider with dietary nitrate is that the exact content can vary depending on time of the year, soil conditions and storage methods. Vegetables are the highest source, although small amounts can also be found in items like water and cured meats.
The absolute bioavailability for dietary nitrate is 100 percent, and the peak plasma levels after dietary consumption are typically reached 1.5-1.8 hours post consumption. The European Food Safety Authority established an Acceptable Daily Intake for nitrate of 3.7 mg/kg daily (0.06 nmol/kg). For a 70kg adult this equates to about 260 mg/d (around 4.2 nmol). In the nitrate loading study, athletes had nearly double the plasma nitrate amount (8.2 nmol), equating to 1.95 times more or 7.2 mg/kg daily. For the same 70kg adult this would mean 505 mg daily.
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