Dr. Allen Lim is a big believer in beet juice.

If you're like many serious (and even some not-so-serious) cyclists, the idea of legal athletic performance enhancement is intriguing. Who doesn't want to beat their buddies up the next hill, bag a Strava KoM, or just feel better on (and off) the bike?

Well, these days there is growing evidence that that boost might just be available via the juice. And no, we are not talking the kind of nefarious "juice" obtained from Alex Rodriguez's Biogenesis Lab. We're talking the good old fashion fruit and vegetable kind.

One study, first highlighted in this New York Times blog, claimed that cyclists who drank beetroot juice before a 10-mile time trial where 3 percent faster than when they didn't drink the juice. The folks from WebMD are also on board with beets, saying that, "a diet rich in beet juice may be a natural approach to help lower blood pressure and improve heart health," and that "beet juice can also have a positive effect on the body during exercise. A recent study showed six days of beet juice enhanced overall physical performance and heart functioning during exercise."

While it's not entirely clear what beet juice does to make athletes faster, one of the doctors involved in the study believes that the liquefied beetroot helps improve blood and oxygen flow to muscles, and also helps those muscles use the oxygen more efficiently.

Another concoction receiving attention is tart cherry juice, which some researches claim can help athletes during the all-important recovery process. Researchers at the Nicholas Institute of Sports Medicine and Athletic Trauma at Lenox Hill Hospital in Manhattan have found that the juice from sour-tasting Montmorency cherries helped "reduce muscle pain and weakness" after intense strength training and after running a marathon.

And even if it turns out that none of this is actually true, juicing is a great way to get the important nutrients and vitamins in our diets without turning to supplements or other less organic methods.

"Juicing is a great way for athletes to increase the nutrient density of the foods they eat without increasing the fiber load," explains Dr. Allen Lim, a sports physiologist Ph.D. who has worked as a nutritional consultant for a number of professional cycling teams and is the author of the Feed Zone Portables cookbook. "Fruits and vegetables contain a substantial amount of nutrition but also contain a lot of fiber. With a lot of the athletes I work with, they burn so many calories in a day and need to consume so much food to keep up with their nutritional needs that if they consumed all that nutrition in solid form, they would literally create a huge load on and in their gastrointestinal system because of all the fiber. So rather than fill them up with empty calories, I'd rather see them juice."

Here's Lim talking more about juicing:

httpv://www.youtube.com/watch?v=9uCXeDFUSxk

Lim recommends trying a variety of blends until you find something you like. He likes juicing fruits and vegetables that taste great in whole form, that are dense, and, that contain a decent amount of water. That includes foods like carrots, oranges, kale, beets, apples, cucumber, red peppers, cucumbers, spinach, celery, pineapples, blood oranges, arugula, tangerines, peaches, nectarines, plums, grapefruit, and green peppers, which can all make a great base for a juice. Ingredients like ginger, lemons, and limes can be a great flavor addition in small amounts, he adds.

As for timing, Lim recommends juicing in the morning, which normally means before a workout. "The rule of thumb is to limit the fiber load before the workout and maximize the fiber load after the workout," he says.

As for the athletes themselves, juicing is typically viewed as primarily a path to good health rather than a true performance booster. "I just think it's good for you," says Jake Wells, a pro cyclocross racer who also runs a coaching business. "You can get a lot of nutrition into a glass of juice versus eating a giant salad."

Wells favors beet juice mixed with apple juice for improved flavor. "I eat beets in all forms a lot," he adds. "They are good for recovery because all the iron acts as a blood builder."

Fellow pro bike racer Jeremy Powers sees similar benefits. "I definitely feel like I have more energy when I'm making different juices regularly," he says. "And it's good to know that I'm getting all of the different vitamins and minerals from them. But I guess we'll see this coming race season if it's had any real benefits."