By Anne Guzman, PCG Nutritionist
Several studies have now confirmed the effects of nitrates on athletic performance including a study done at the University of Exerter’s School of Sport and Health Sciences, using beet juice. The study looked at 8 male cyclists consuming half a liter (500ml) of beet juice (approx. 2 cups), containing nearly 700 mg of naturally occurring nitrate, for six days. The control group with the placebo drank 500 ml of black currant cordial containing very minimal nitrates for the same amount of time. The cyclists completed a series of ‘stepped’ moderate-intensity and severe-intensity exercise tests on a cycling ergometer during the last three days of this period. On the fourth day of supplementation, subjects completed two bouts of moderate cycling, while on days five and six the subjects completed one bout of moderate cycling and one bout of severe cycling. In the severe cycling test, the loading was increased by 30 watts per minute until the subject could no long continue. After this six-day period, subjects underwent a 10-day ‘washout’ period during which neither beetroot juice nor cordial were consumed, then the supplement protocol was reversed (those who had taken beetroot took cordial and vice-versa). Throughout this time, all subjects refrained from eating any high-nitrate foods to ensure that any differences were due to the beetroot juice.
The beet juice group was able to cycle an average of 16% longer. The men also had lower resting blood pressure after consuming the beet juice compared to the currant juice. The author, Professor Andy Jones, noted: “Our study is the first to show that nitrate-rich food can increase exercise endurance. We were amazed by the effect of beet juice on oxygen uptake because these effects cannot be achieved by any other known means, including training.”
The results from the study are as follows;
• As the exercise intensity increased, the extra oxygen demand to provide this increased power output rose more slowly in those taking beetroot juice (the beetroot condition required an extra 8.6 mL of oxygen per minute per additional watt of power output whereas the placebo required an extra 10.8mL per minute per additional watt);
• The time-to-exhaustion in the ‘severe test’ was significantly extended when beetroot juice was taken compared to placebo (675 seconds vs. 583 seconds, an increase of 16%!);
• The ‘slow component’ of oxygen uptake (you can think of this as the ‘lag’ in the aerobic system while oxygen supply catches up with demand) was reduced by about 0.2 L per minute in the severe test when beetroot juice was taken, indicating that the aerobic system was more efficient at getting up to speed during intense exercise:
Whether you are a professional athlete or a fitness enthusiast, these significant findings are great news! Who doesn’t want to naturally boost their performance? The performance boost, researchers say, is due to the high levels of nitrates in beetroot juice. While it's not totally clear how it works, the authors suspect that when dietary nitrate turns into nitric oxide in the body, it reduces the amount of oxygen required to perform exercise. Nitric oxide has many functions in the body, one of the key ones is that it facilitates vasodilation or widening in blood vessels, which promotes increased blood flow and regulates blood pressure. Nitrates also function to help with muscle contractility, glucose and calcium homeostasis and mitochondrial respiration. More research needs to be done in order to understand exactly how nitrates are producing these results, however the results are significant and so far they are worth juicing for!
With regards to blood pressure, a study published online in the American Heart Association Journal --Hypertension, found that blood pressure was lowered within 24 hours in people who took nitrate tablets, and people who drank beetroot juice. This was a follow up to a previous study that wanted to isolate nitrates as the cause for the blood pressure reduction.
Study author Amrita Ahluwalia, Professor of Vascular Biology at Queen Mary's William Harvey Research Institute notes, "We showed that beetroot and nitrate capsules are equally effective in lowering blood pressure indicating that it is the nitrate content of beetroot juice that underlies its potential to reduce blood pressure. We also found that only a small amount of juice is needed -- just 250 mL -- to have this effect, and that the higher the blood pressure at the start of the study the greater the decrease caused by the nitrate.”
This is a great sign if it is any indication of where heart health remedies could be heading, as it may offer a more natural approach to reducing blood pressure than taking drugs. More studies need to be done in the elderly populations with other risk factors; however researchers believe that the results should be consistent. I am sure there will be more studies coming in the near future.
The Practical Beet
A few notes on juicing beets. If you have tried this you will know that the taste is not necessarily appealing on its own; unless of course you enjoy the taste of the earth? You can cut the taste by mixing in some juiced apples or carrots and a bit of ginger. Spinach is also very high in nitrates however it may not really improve the taste that much. (My favorite juicing combo is beets, apples, carrots and ginger!) Some people may react to beetroot juice with hives or headaches. I recommend that you experiment well before competition day, as you don’t want to undermine all of your hard training with a negative physical reaction. I generally would never try something new on race day. Some people will have red urine or stools from beet juice so don’t be alarmed! This is very normal. No need to get out the will!
Beside the performance enhancement and blood pressure reduction, beets offer great nutritional value; Betalains, which are what give beets their red/violet pigment, function as antioxidants and anti-inflammatory molecules. Betalains are sensitive to heat from cooking. To preserve the nutrients in the beets cut them into quarters and steam, keeping cooking time under 15 minutes. Store beets in a cool place and leave the greens on if possible while cooking to keep in more of the nutrients. Peeling beets is easier once they are cooked. If you have not cooked with beets before, I will fore warn you that they do stain! I would recommend gloves and no white t-shirts☺. Beets are a great way to add color and nutrients to any meal, and a good way to get the edge on the competition!
Tour De France competitors have been drinking beet juice for a few years now. When we are talking about professional and amateur athletes, any legal edge they can get can make the difference between first and second place. And as we know races like the TDF can be won by mere seconds. In fact, recently the 2012 Giro D’Italia came down to a fierce battle! (If you didn’t watch it…you should!) I’m guessing Ryder had his beet juice that morning ;).
(Pregnant women should not drink beet juice without first consulting their doctor. This article is not meant to replace any medical advice. People with high blood pressure, heart problems, or who are on medication should consult with their doctors to be sure that beet juice will not interact with any medications or cause any negative reactions.)
1. Beetroot Juice Boosts Stamina, New Study Shows Science Daily (Aug. 6, 2009)
2. Andrew M. Jones et al. “Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.”
3. Dr. Richard E Klabunde. Cardiovascular Physiology concepts; Nitric Oxide. Online Article (Sept.23, 2008)
4. Nitrate in Beetroot Juice Lowers Blood Pressure, Study Finds; Science Daily (June 28, 2010)
This article has been reprinted from Pez Cycling News Online. Anne Guzman is a regular contributor to Pez Cycling News Online.
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