Tag Archives: competition

Does beetroot juice work for you?

Drinking beetroot juice before a race has become very popular, as it can make you go faster. However, a new study suggests that beetroot juice will not help you if you are already very fit.2631746551_ba1338f5b7

Studies have shown that a single intake or a short term (3-6 days) supplementation of beetroot juice shortens your time on a time-trial event and allows you to tolerate high intensity exercise much better. This is because beetroot contains nitrates (NO3-).

Your body absorbs NO3- and secretes it into your saliva, where your mouth bacteria transform it into NO2-, which is then taken up by your stomach as you swallow. (That is why beetroot has no effect if you use antibacterial mouthwashes.) NO2- becomes NO in tissues which are in need of oxygen, such as working muscles.

NO dilates blood vessels and makes your body more efficient at using oxygen to produce energy. It also improves the contractibility of your muscle fibres.
This is great news, not only for athletes, but also for the elderly who have a reduced aerobic capacity, and for people suffering from hypertension as it will lower their blood pressure.
However, there is a problem. Most studies showing a benefit have been done on sedentary or moderately fit people. Studies on elite athletes on the other hand, are rather disappointing.

To try to understand this better, Simone Porcelli and her colleagues have studied the effect of beetroot juice on 21 young men of different aerobic fitness levels. The VO2 max values of the participants ranged from 28.2 ml/kg/min (sedentary people) to 81.7 ml/kg/min (elite level).
The researchers tested their fitness by a run to exhaustion, a series of 6-min sub-maximal runs on the treadmill, and a 3 km time trial. All the participants performed the tests twice, once after taking 500 ml/day beetroot juice for 6 days and once after drinking the same amount of a placebo for the same time.

There was an inverse relationship between the VO2max of the participants and the benefits of taking beetroot juice. In other words: the participants with the highest VO2max showed the least benefits, while those with the lowest VO2max benefitted most. The researchers also measured the blood levels of NO3- and NO2- of the participants, and noted that the fitter ones showed a smaller increase after drinking beetroot juice.

These results are not easy to explain, and Simone Porcelli and her colleagues have come up with 3 possibilities:

1) NO2- is mainly transformed into NO when tissues need oxygen. Elite athletes will have more blood vessels in their muscles due to many years of training, and it is therefore possible that the right conditions to form NO happen only rarely.

2) Athletes might take in much more nitrates with their normal diets, as they are likely to eat more than sedentary people. In this case the supplements would not matter anymore, and could just end up in their urine. Unfortunately, the researchers did not check the urine levels.

3) Our bodies can also make NO via a completely different pathway, without the need of any dietary NO3-. It is possible that many years of training have optimised this system and fine-tuned the athletes’ metabolism, making nitrate supplements superfluous.

The researchers noticed a higher NO3- and NO2- blood level in the fittest participants before taking any juice, which makes one of the two last possibilities (or both) more likely than the first one.

Whatever the reasons, if beetroot juice does not work for you, you should be happy!

photo credit: <a href=”http://www.flickr.com/photos/24987280@N00/2631746551″>Beetroot</a&gt; via <a href=”http://photopin.com”>photopin</a&gt; <a href=”https://creativecommons.org/licenses/by-sa/2.0/”>(license)</a&gt;

 

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Altitude training for endurance athletes

© Ichtor | Dreamstime Stock Photos
© Ichtor | Dreamstime Stock Photos

There is no doubt that if you want to compete at altitude, you will first have to acclimatize to the lack of oxygen. If not, you will probably not perform as well as you could and you will certainly put your health at risk. However, does training at altitude help you to perform better at sea level? The jury is still out…

Lorenzo Pugliese and colleagues have published the latest article about this question in the September issue of the Journal of Sports Science & Medicine. It is an observational study of two elite endurance athletes, a race walker and a marathon runner, who used altitude training as part of their preparation for the Athens Olympic Games (2004). As both of them obtained gold medals, it must have worked for them, even though we do not know for sure what would have happened if they had stayed at sea level.

Even though altitude training is popular between endurance athletes and coaches, it is still controversial between scientists. In theory it should work of course: as the air pressure is lower at altitude, your body learns how to use oxygen more effectively, what then allows you to perform better when you are back at sea level. The best known effect is an increase in red blood cells, and thus in haemoglobin mass, although there are also adaptations at the level of the muscles and the mitochondria. This increase is triggered by the hormone erythropoietin or EPO, which is produced by the kidneys. However, some people produce less EPO than others and there are therefore important inter-individual differences between the effects of altitude on athletes.

Training hard and altitude

If you want to win endurance races, you need to be able to train at fast paces. Running fast for a long distance is difficult to do at altitude when you are not used to it, as your muscles need more oxygen than you can deliver to them. This is even more so for elite athletes, whose muscles are trained to perform at an optimal level. If you do not train intensively enough for a period of a time, your muscles become detrained, and anything you might have gained by improving your oxygen metabolism will be useless.

While you are acclimatizing, you will face some other problems:

  • Sleeping can be difficult as you are short of breath.
  • As soon as you arrive at altitude, your plasma volume (=the water part of your blood) will decrease, as your body wants to increase the red blood cell concentration and producing new red blood cells takes some time.
  • The air is colder and drier which can easily lead to dehydration.
  • As your muscles cannot extract as much oxygen from your blood as they do at sea level, your VO2max is in effect reduced. Running at the same speed as at sea level will therefore mean working at a higher level of your VO2max, which will feel harder.
  • You are more vulnerable to infections.

All these factors will make it difficult to train at the required level during the acclimatization. Once you are used to the altitude the situation will improve, but in the meanwhile you might have lost valuable time and your legs might have lost speed.

Athletes and coaches have therefore developed live-high-and-train-low camps, whereby they live at altitude and train at lower level. Alternatively, they might do live-low-and-train high camps, whereby they perform some of their sessions at altitude to have an additional training stimulus.

 Olga Vasilkova | Dreamstime Stock Photos
Olga Vasilkova | Dreamstime Stock Photos

Reasons for the controversy

Studies about altitude training contradict each other, whatever formula they use (live-high-and-train-high, live-high-and-train-low or live-low-and-train-high). It is of course possible that athletes and coaches have noted some benefits that are too small to be measured by scientists. As major championships are won or lost by seconds, such very small benefits can make a big difference indeed.

It more likely that the controversy is due to a lack of control groups: in a good study you would compare similar athletes doing the same training at altitude as at sea level, and you would take into account that some people do not react as well as others. In practise such a study is very difficult and expensive to conduct. To complicate matters even further, there could be a placebo effect, as most athletes believe that altitude training is beneficial.

Lorenzo Pugliese’s athletes followed a live-high-and-train-high program. However, they were able to train at the same running/walking pace as at sea level and, according to Pugliese, this is the reason why the camp worked so well for them. Both of them had extensive altitude training experience and that might well have been the reason for their success. Maybe a three week camp so now and then is simply not enough, and you might need to live for a long time at altitude to reap the benefits? This would explain why so many top endurance athletes are born and/or live at altitude. Bad news for all of us who live at sea level though…

References

D M Bailey and B Davies. Physiological implications of altitude training for endurance performance at sea level: a review. Br J Sports Med. 1997; 31:183-190.

L Pugliese, FR Serpiello, GP Millet et al. Training dairies during altitude training camp in two Olympic champions: an observational case study. J Sports Sci Med. 2014; 13(3):666-672. eCollection 2014.