T Nation

Beetroot Boosts Stamina


#1

Interesting findings on beetroot juice

http://www.news.com.au/story/0,27574,25899980-23109,00.html

Beetroot juice 'boosts sports stamina'

A GLASS of beetroot juice boosts endurance by reducing the amount of oxygen needed during physical exercise, a study says.
Subjects who drank the juice easily outperformed a control group in tests and were able to exercise at the same intensity for up to 16 per cent longer.

The findings, published in the US-based Journal of Applied Physiology, will be of keen interest to endurance athletes but may also prove helpful to people with cardiovascular, respiratory or metabolic diseases as well as the elderly, the researchers said.

There are essentially two ways to enhance physical performance in relation to oxygen intake.
One is to raise the "VO2-max" level, which is an individual's highest possible rate of oxygen consumption during all-out exercise.

The V02-max ceiling varies from person to person. It is partly genetic but it can be increased through training or the use of EPO, the oxygen-boosting drug that has plagued the Tour de France cycling competition as well as other professional sports.

"But there is an alternative," explained Andy Jones, a professor at the University of Exeter in Britain and lead author of the study.

"If you can reduce the energy cost" - the amount of oxygen used - "that can be beneficial too," he said.

That's where beetroots come in.

In experiments, Prof Jones and colleagues asked two groups of people to exercise at a fixed, high-intensity work rate for as long as they possibly could.

The group that drank a red-coloured placebo held out on average for nine or ten minutes. Those who drank beetroot, however, went 11 or 12 minutes.

"They were exercising at exactly the same work rate. The improvement in performance was not because the V02-max had changed but simply because the efficiency had been enhanced," Prof Jones said.

"We were amazed by the effects on oxygen uptake because these effects cannot be achieved by any other known means."

Whether the juice will also work over several hours of less intense exercise - equivalent to long-distance running or cycling - remains to be shown but seems likely, Prof Jones added.

The researchers are not sure exactly how the ruby-red elixir works but they do have an educated guess.

Like lettuce and spinach, beetroot is rich in nitrate, which the body converts into nitrite. This, in turn, is a chemical trigger for another compound, nitric oxide.

Nitric oxide can dilate blood vessels and thus provide more oxygen to muscles. "But we think the key is that it seems to do a lot of weird and wonderful things within the muscle cells' mitochondria, where oxidated energy is produced," Prof Jones said.

Earlier laboratory studies confirm the link between nitric oxide and increased energy output but further experiments are needed to see whether this truly is the magic ingredient.

Another study, published last year in the US journal Hypertension, found that beetroot juice reduces blood pressure too


#2

It is impossible really to give substantive, detailed commentary on this because I can find online nothing but this popular-press account of a study. Neither Pubmed nor Google Scholar turns up anything.

A general commentary is this: While it is commonly believed that if statistical calculation assigns a p value of less than or equal to 0.05, this means that the apparent effect probably was from actual effect rather than just from chance, actually it does not mean this at all.

If a proposition is unlikely in the first place, the p value can 0.05 while the probability, given information available, of real effect having caused it may be thousands or millions to one against.

For example, suppose that rats are tested to see if they live longer if their water bottles are filled with water that had been swirled to the right before being filled, vs being swirled to the left or unswirled.

Now going into this thing, we would estimate that the likelihood of there being an actual longevity-enhancing effect from the water swirling should be considered as essentially zero.

We have 10 rats in each group, and simply by randomness some rats live longer or shorter than others.

However, the average lifespan for the right-swirled-water group wound up being substantially longer than for the other groups. And the statistics give a p value of 0.05: the actual meaning of this is that if we were generating the numbers randomly with the variation seen, only 5% of the time would chance alone produce an effect as big as was seen.

It is no commentary on whether in this actual case the cause was an actual effect, or chance alone.

In fact, if 100 experiments that all have no actual effect are done, 5% of the time there will be an apparent result that meets the p <= 0.05 standard. And needless to say a lot more than 100 experiments are done per year.

Any rational person would conclude that regardless of the p = 0.05 value, he should not conclude that swirling the water to the right makes rats live longer. The proposition was too unlikely to begin with. One shouldn't take the idea seriously until the p value is way, way, way lower than that. The more unlikely the proposition, the lower the p value one should demand.

In this case, the entire concept that the same work can be performed with markedly less oxygen by ingesting some substance is one that should be considered very unlikely in the first place.

Thus, if the p value was only p <= 0.01 or something like that, the most likely explanation is chance alone, or systematic experimental error.

Secondly, the nitric oxide explanation seems completely silly at explaining, or attempting to explain, same work done with less oxygen.

Lastly, it doesn't seem to me that Professor Jones' explanation of enhanced oxygen efficiency is necessary to explain the results stated in the article. Now if we had the data maybe we could see where he is getting that from, but it doesn't follow from what the above article says.

Interesting conclusions, but I think dubious (for the above reasons.)

Simply extending duration of work at same output and oxygen consumption, and there's nothing in the above article that states oxygen consumption was measured as less for same work, is not new, though their finding a new way to do it, if they did, is interesting.


#3

Placebo... containing an equal amount of carbohydrate?