Nitric Oxide (NO) is a supplement currently used by many athletes because it is a known vasodilator, which can increase blood flow, mitochondrial efficiency, and contractility of muscles. While there are a few different kinds of nitrate supplements, the most common comes in the form of beetroot juice. When ingested, the nitric oxide is easily broken down into nitrate, which can be used by the body to help increase efficiency of exercise. Multiple studies have been done regarding the effect of beetroot juice supplementation in both trained and untrained athletes; as well as by acute or long term dosing. Due to the nature of NO in exercise, it is generally used to supplement endurance activities, with only a few studies looking at shorter length, or strength exercise. Currently, there is data to suggest that beetroot juice has a more noticeable effect in untrained individuals than in trained athletes, which is not surprising. The trend normally seen in these studies is that acute doses of beetroot juice will lower VO2 during submaximal exercise, allowing individuals to exercise more efficiently. Another effect of nitrate is the increase in mitochondrial efficiency. This effect was tested through long term studies regarding beetroot juice supplementation. In low-moderately trained athletes it was also found that VO2 decreased at submaximal exercise, similar to acute dosing. Additionally, exercise tolerance was also increased by up to 16% after one week of supplementation. While this may be due to the effects of training it was a significant difference. In highly trained athletes, it was found that beetroot juice increased workload and reduced energy cost at exercise intensity. However, the variability in performance could have been the cause of this as noted by the authors of the study. Overall, while there is some evidence to support the use of beetroot juice as an ergonomic aid, there is also a large amount of data to suggest that it has very little to no effect of athletic performance.
Table of studies done to research the effects of acute nitrate supplementation in elite athletes
This topic relates to class in that it aims to determine what affect different training methods/supplements have on athletic performance. It seems that there are potential benefits to using beetroot juice or other nitrate supplements as a training tool in both acute and long-term doses. One of the issues seems to be in determining the proper dosage of beetroot juice. There were multiple studies where no benefit was seen with small doses and significant benefits were seen with a higher dose. Determining this value will be important in future studies to ensure that possible benefits are not being overlooked. Additionally, larger studies should be conducted as only one study referenced in the article had more than 20 subjects. This could be a potential major limitation given the large amount of variability in and between different athletes and sports. NO supplements also would seem to be more beneficial to endurance athletes than it would be to strength athletes during training. While there is only a small amount of evidence to support the claim that beetroot juice will improve athletic performance, there is no data to suggest that taking this supplement will have negative effects on performance so trying it in your next training cycle may be worth it.
References Andreas Zafeiridis. The Effects of Dietary Nitrate (Beetroot Juice) Supplementation on Exercise Performance: A Review. American Journal of Sports Science. Vol. 2, No. 4, 2014, pp. 97-110. doi: 10.11648/j.ajss.20140204.15
I wonder if consumption of NO on a regular basis would cause a hormonal imbalance. If the body is regularly being supplemented would it build a tolerance? We learned that norepinephrine and epinephrine are the hormones that cause vasodilation to occur. I’d be curious to see after long term usage of NO or other supplements to cause this type of effect on a person’s vasculature would inhibit the release of these hormones.
This is an interesting study, I wonder how beetroot juice affects the body during rest, or those with low blood pressure. As a vasodilator, I imagine consuming beetroot juice in high quantities could be dangerous for those with low blood pressure, increasing the risk of passing out. However maybe the effects are not that dramatic. Maybe I’ll try it next time I work out!
I agree with Margot in that supplementing with beetroot juice could be potentially harmful, particularly in those with already low blood pressure or even in those taking other vasodilators. I would like to see larger studies to help determine whether the noticeable decrease in VO2 and increase in exercise tolerance is a result of the supplementation or just a training effect.