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18/10/2022
Many products containing diverse substances aiming at improving sports performance are available on the market. Some do not have any significant performance benefits and only rely on the placebo effect to possibly improve performance. Others have many benefits but are harmful and illegal. Only a few substances were found to be beneficial for sports performance after conducting rigorous studies. For decades, extensive research investigating the effect of dietary nitrates on sports performance was undertaken, with many showing benefits in some situations and at specific doses.
To understand the potential role of dietary nitrates in improving sports performance, it is important to understand how the body works to produce energy when taking part in endurance events such as a 10k running race or a cycling time trial. When we are exercising for a long time, we cannot reach and maintain the highest intensities. As a result, we need to exercise at a lower intensity, which is called sub-maximal. At this intensity, energy is mainly generated through the aerobic system, which means that the energy for the muscles to work is generated using oxygen. This mechanism allows our body to utilise glycogen and fat stores and maintain the effort over a long duration. However, compared to the anaerobic system, this way of producing energy is slower. This is why the sustainable intensity is lower.
According to the previous point, it is therefore essential to maintain an important quantity of oxygen delivered to the muscles to achieve optimal performance. Oxygen is transported through the blood and is then delivered to the muscles through diffusion from the blood capillaries to the surrounding muscle fibres. Numerous solutions exist to improve oxygen delivery to the muscles. However, to understand the effects of nitrates, we will focus on vasodilation (increased diameter of the blood vessels) which increases blood flow. When dietary nitrates are ingested, they are reduced in nitrite, and then in nitric oxide. Studies found that nitric oxide plays an important role in blood flow as well as muscle contractions and cellular respiration. Results from studies show that the ingestion of nitrates decreases oxygen cost during endurance performance at a sub-maximal intensity. This means that energy production is more efficient, which allows someone to run faster at the same intensity.
After discussing the performance benefits and the mechanisms of action of dietary nitrates, it is now time to touch upon where to find nitrates in our diet. Most leafy greens hold important concentrations of nitrates such as spinach, lettuce, or pak choi. Other vegetables such as carrots or beetroots contain a good amount of nitrates and participate in their daily consumption. However, their concentration varies substantially depending on the environmental conditions in which the food was produced, as well as the time spent since they have been harvested. You should also be careful with added nitrates in processed food (salami, bacon, or cured ham more generally) as they do not have the same benefits as natural nitrates and need to be avoided. As a result of many positive findings found by research about performance improvement with nitrates ingestion, many sports products containing nitrates were made. It is now possible to buy beetroot shots holding an important amount of nitrates, as well as sports powders containing nitrates to facilitate their ingestion for people not consuming natural products containing them or for those who do not have access to them. However, it should be noted that natural foods would benefit an individual more compared to the isolated supplement form due to the presence of many vitamins and the whole food matrix.
We will now be discussing doses and timing. Several studies found performance improvements when nitrates were ingested on multiple days whereas others found improvement with single ingestion. For the best results with ingestion only on the competition day, studies found that 5-9mmol (around 310-560mg) 2-3h before the effort was optimal. A similar intake every day for more than 3 days was found to be effective in elite athletes that would not benefit from a single dose.
However, it is important to find, in the recommended range, the maximal dose that each individual can handle as an excessive intake may lead to gastrointestinal distress. As for all nutritional strategies, it is essential to try it during the training before implementing it for an event as the body may react badly and eliminate any chance of great performance. Tolerance to the nitrate dose can also be trained. By starting from a low dose and increasing it little by little, it is possible to increase the maximal dose that someone can handle without feeling any discomfort. However, increasing the dose does not always lead to improved performance. There is a limit after which no further improvement is observed, and it seems to be 9mmol.
It should also be noted that it is important not to use mouthwash before ingesting nitrates as it removes all the bacteria needed to reduce nitrate into nitrite and nitric oxide which negates all the potential positive effects.
To conclude, nitrates can be beneficial to endurance sports performance by improving energy production from the aerobic system by making it more efficient. Nitrates can be found in leafy greens as well as other vegetables such as beetroots and carrots. Nowadays, several sports products such as beetroot shots and sports powders contain optimal nitrate intakes to improve sports performance. The recommended dose is 5-9mmol 2-3h before the effort or a similar dose every day for more than 3 days for elite athletes who do not observe any significant benefits from the single-day intake. As for every nutritional strategy, time is needed to practice it and improve it during training. In terms of sports products containing nitrates, make sure to buy products that have the lowest risk of containing doping substances, through the appearance of the “Informed Sport” logo on the packaging for example.
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