THE JOLT IS LEGIT
The performance boost you get from caffeine is a result of how it hot-wires your central nervous system, says Matthew Ganio, PhD, an exercise physiologist at the Institute for Exercise and Environmental Medicine in Dallas.
"Caffeine crowds out a calming brain chemical called adenosine," he says. You become more alert, you react faster, and you don't feel like you're working as hard, all of which add up to training or competing at a higher intensity for a longer period of time and being more agile in a pack.
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IT WILL NOT DEHYDRATE YOU
"In reasonable doses, caffeine alone won't lead to more bathroom breaks during a ride or a greater risk of dehydration," says Mindy Millard-Stafford, PhD, former president of the American College of Sports Medicine. The upshot, she says, is that regardless of whether you supplement with caffeine, you don't need additional fluid to avoid performance-sapping dehydration during a ride. The long-held belief that caffeine can muck with your body's ability to regulate heat during exercise in hot weather has also been muted by science.
IT AFFECTS EVERYONE DIFFERENTLY
Before breaking out a venti on event day, Ganio suggests testing what caffeine does to you during hard training sessions. "If you feel jittery, anxious, or notice your heart racing, dial back the amount you take in before a ride," says Ganio. "If you can't find a caffeine level that leaves you feeling comfortable, skip it. Side effects can impair performance."
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YOU CAN DEVELOP A TOLERANCE
Your body eventually adapts to the effects of caffeine, limiting the performance benefit. If you regularly drink more than five daily cups of coffee, Ganio recommends tapering your intake by a half cup a day for several days prior to a big ride, saving higher amounts of caffeine for before and during actual events.
TIMING IS EVERYTHING
It takes 60 minutes for caffeine to start affecting the body, so imbibe one hour before a ride. "For rides lasting two hours or more, take half of your caffeine before and the other half in divided amounts during the ride," says Ganio, "making sure to consume the remainder when there is more than an hour left in your ride." Say you plan to take 200mg of caffeine for a three-hour ride: Aim for 100mg one hour before you get on the bike, and 50mg at the beginning of each hour thereafter.
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TRAINING TRUMPS IT
"While caffeine can boost performance by 3 to 5 percent, training can bring about improvements by upwards of 50 percent," Ganio says. There's also the possibility of getting over-amped and going out too hard too soon, leaving you with nothing in the tank well before the ride's end. Bottom line: No amount of caffeine will turn a donkey into a thoroughbred.
The Facts on the Fix
WHAT YOU NEED
It takes about three to six milligrams of caffeine per kilogram of body weight (190 to 380mg for a 140-pound rider) for most people to notice a performance benefit, says Millard-Stafford. "Higher doses are more likely to cause side effects," she says, "and there's no evidence that extra caffeine provides additional performance benefits." During training, start at the lower end of the dose recommendation and work up to the level that's best for you.
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