�����ԹϺ���

IN 2010, OLYMPIC marathoner Ryan Hall boldly predicted that he was going to be the first American in nearly 30 years to win the . A month before the event, however, he not only dropped the race from his competition schedule, but he was forced to cancel his entire season due to extreme fatigue. Afterward, he broke with his coaches, then regrouped and examined every aspect of his running to figure out what had gone wrong, eventually targeting a few crucial aspects of his training and nutrition regimen. One of the more unusual new tactics he incorporated was chasing each run with eight ounces of an unappetizing-sounding drink: beet juice.

The strategy isn’t as odd as it sounds. In 2009,  done at England’s caught the attention of the fitness world. Researchers discovered that competitive cyclists who drank half a liter (about 16 ounces) of beet juice right before they got on their bikes were able to ride 16 percent longer—a massive gain in a sport where only a few percentage points of improvement can be the difference between first place and fifteenth.

Last June, a larger Exeter study backed up this rather unusual protocol: cyclists who drank half a liter of beet juice for six days were 11 seconds faster over a 2.5-mile course and 45 seconds faster over a 10-mile course. The reason: more oxygen was getting to the athletes’ muscles, thanks to molecules in the juice called nitrates. “The oxygen cost of exercising at a given speed is basically fixed,” says , a professor of applied physiology at Exeter and lead author of both studies. “Only nitrate ingestion appears to improve efficiency. These effects cannot be achieved by any other known means, including training.” 

It works like this: Our bodies convert nitrates into nitric oxide, a gas that causes blood vessels to relax and widen, by a process known as vasodilation. This allows more oxygen-rich blood to flow through the body—and the more oxygen reaches the muscles, the longer they’re able to perform at high intensity. Athletes have tried to trigger vasodilation with various banned substances, including hypertension drugs and erectile-dysfunction medication, for years. It now appears that simply consuming large amounts of vegetables that are high in nitrates, such as spinach, carrots, radishes, and beets—the last of which pack the biggest punch, a whopping 310 grams per 16 ounces of juice—can offer the same performance boost.

Of course, loading up on nitrates isn’t without its risks. Synthetically produced nitrates, which are sold at places like and permitted by guidelines, have become a multimillion-dollar industry. But a published in the Journal of the International Society of Sports Nutrition noted that, because extended vasodilation causes blood pressure to drop, overconsumption “can lead to cardiovascular collapse, coma, and death.” And according to , a sports physiologist and nutritionist at , there are also long-term negative effects associated with synthetic nitrates. “Continued use causes the body to stop making nitric oxide, which our bodies produce naturally to regulate blood pressure,” she says. “And that will cause high-blood-pressure issues down the road.”

Is the quantity of nitrates in a glass of beet juice enough to create these kinds of problems? No, according to Allen Lim, a sports physiologist best known for helping train professional cyclists like Lance Armstrong and Taylor Phinney. Lim liberally doles out fresh beet juice to his athletes. Sims is more cautious. “Natural nitrates found in whole foods are safer,” she says. “But even ingesting too much of those could be bad for you.” Instead, Sims, who works with several world-class athletes, prescribes 3,000 to 6,000 milligrams of another natural vasodilator, beta-alanine. The amino acid, found in foods like poultry, pork, beef, and fish, can be taken in powder or pill form and produces only about one-eighth the amount of nitric oxide that nitrates yield. But it also slows down production of lactic acid in muscles during exercise, and that can help prevent fatigue. A done at England’s found that cyclists who took beta-alanine were able to increase the amount of time they spent riding at maximum wattage by 12 percent. “And it’s safe,” says Sims. “No study has ever found that it’s not safe.”

For Hall, adding beet juice to his routine seems to be paying off, and not just on race day: nitrates may have increased his ability to train harder longer, a critical factor for an elite runner who once suffered from fatigue. Last year, Hall ran the , finishing fourth in Boston. In January, he qualified for the London Olympics, and he’s considered a legitimate contender for a medal. “I can’t say it was all thanks to beet juice,” he says. “But I’m running well, so I’m going to keep drinking it.”

How Much Beet Juice Is Too Much?

The jury is still out on dosage guidelines for nitrates and beta-alanine, but here are recommendations from two top nutritionists

Allen Lim: “Beet juice is 100 percent natural, and there are nutritional benefits beyond the nitrates, like antioxidants. I’ve seen some of the best real-world performances from athletes who make it part of their diet.”
Dosage: Eight ounces (two juiced beets) three times a week. Blend with eight ounces of sweeter fruit juices, like apple, carrot, or tangerine, to improve the taste. 

Stacy Sims Says: “The immediate benefit of beta-alanine is that it increases carnosine, and higher carnosine levels have been shown to improve performance by helping to buffer acidosis and increase nitric oxide.”
Dosage: Three to six grams orally per day (about four ) for four to eight weeks. The most dramatic increases will occur in weeks three and four, but carnosine levels can remain elevated for months, so cycle in beta-alanine every 12 weeks to maximize effectiveness.