Beyond beet juice: L-arginine also boosts endurance


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Andrew Jones, the man behind the beet juice fad of 2009, has more performance-enhancing revelations in a study just released online in the Journal of Applied Physiology. He found that taking the supplement L-arginine produced very similar effects to beet juice: by reducing the “oxygen cost of exercise,” it allowed subjects to last 20% longer in a ~10-minute cycle to exhaustion (11:47 versus 9:22 for controls) in a placebo-controlled double-blind trial. They estimate that’s equivalent to a boost of 1-2% in a fixed-distance race. (Abstract here, press release here.)

What’s significant here is that L-arginine acts in basically the same way as beet juice. Beet juice contains nitrate, which the body converts to nitric oxide, which has a number of effects such as dilating blood vessels and lowering blood pressure, ultimately allowing the body to perform more work from the same amount of oxygen. L-arginine is also converted by an enzyme to nitric oxide, producing the same cascade of effects — and, as the researchers note, the performance boosts observed in the two studies are very similar, giving them confidence that they really do understand what’s happening inside the body.

This is by no means the first L-arginine study — there have been a number of attempts to use it for performance enhancement, with conflicting results. Previous studies have generally given the supplement on a chronic basis — a little bit each day, or even several times a day. In this case, the researchers opted for one big dose, taken an hour before exercise, to make sure that nitric oxide availability really was elevated during the exercise bout. (They used 500mL of a drink called Ark 1, containing 6 g of L-arginine. There are no disclosures in the paper about who paid for the study.) This change may explain why they saw such a clear result compared to earlier studies.

So what’s next? According to the press release, “the researchers are hoping to find out whether combining the two methods could bring an even greater improvement in athletic performance.” In the meantime, perhaps L-arginine will prove to be a more user-friendly option than beet juice. Here’s what Amby Burfoot reported about one world-record-holder’s abortive try:

Two days before the ING New York City Marathon, I asked Paula Radcliffe if she actually drank beet juice. This moved her to stage one: silly giggles. And an embarrassing response. “I tried it once,” she said, “but most of it came out the other end.

9 Replies to “Beyond beet juice: L-arginine also boosts endurance”

  1. You have to be careful with beet juice – it can do strange things to you. Like Paula Radcliffe’s experience, it can also turn your urine or stool a dark red color. If you’re not expecting it, it’ll scare the hell out of you. But if you are expecting the color, it can be a fun start to your day.

  2. I would like to clarify that this study was an independent study. It was me that first approached Exeter with a proposal to research the supplement. No funding was provided to them by Arkworld or its distributors. All that was required was two free samples of the product.

    I would also like to add that no ‘strange things’ will happen to you while using the supplement, except you might go faster.

  3. Thanks for the clarification, Ian. I’m glad to hear it was an independent study. (I’ve only read the preprint of the paper — I assume the final published version will explicitly state the lack of conflict of interest.)

  4. @johan neve
    Hi Johan,

    Yes, the jury is still out on arginine, for sure. One thing to keep in mind, though, is that all the studies in the review looked at chronic supplementation (subjects took some arginine and aspartate every day for several weeks). The Andrew Jones study above was a single large dose taken just one hour before exercise. I don’t know if that’s enough to make a difference, but it’s one possibility.

    Anyway, if you (or anyone else) do try this, let us know how it turns out!

  5. My theory is that arginine will help lower heart rate during running and will help keep you in the aerobic zone longer – which will help increase endurance by allowing your body to burn fat longer. Good for marathoners like myself. A am personally testing this theory out. I always wear a heart monitor when I run so I know how my body behaves. Yesterday was interesting…for the first hour of running my usual route, my heart rate was noticeably lower by about 8 beats. I had a hard time getting it to elevate. Eventually it returned to my normal zones.

    Here is one study unrelated to running or performance that I found this morning. Heart rates were lowered – which is encouraging.

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