A pre-workout jolt
In a recent Australian study of both recreational and advanced runners, those who took about 95 milligrams of caffeine (about the equivalent of an eight-ounce cup of coffee) improved their 5K times by an average of 10 to 12 seconds.
Back in May 2008, Spanish researchers reported that hot, dehydrated cyclists who downed caffeine with their water and carbs could pedal harder for a longer time in steamy weatherthe first study to specifically simulate summertime temperatures. The scientists think caffeine stimulates muscles, thereby helping to offset heat-related fatigue.
Another Australian study found that glycogen, the muscle's primary fuel source during exercise, is replenished more quickly when athletes ingest both carbohydrate and caffeine following high-intensity workouts. Cyclists who drank large amounts of caffeine (five to six strong coffee cups worth!) along with carbs had 66% more glycogen in their muscles four hours after biking until exhausted, compared to when they consumed carbohydrate alone.
It seems that caffeine may speed up the blood's transportation of glucose to the muscles. Since that much caffeine can make you jittery and disrupt sleep, the authors don't recommend trying this at homebut they do hope to study the effects of lower doses in the future.
The truth about caffeine
But waitaren't we warned against consuming too many caffeinated beverages, especially when we're out in the heat? I've always heard that caffeine can be dehydrating, so I posed the question to Nancy Clark, RD, author of the Sports Nutrition Guidebook, Fourth Edition (2008).
"While once deemed true, we now know that coffee is not dehydrating," Clark tells me. "The truth is, a moderate intake of coffee, cola, and other caffeinated beverages do count toward fluid needs, particularly if you are accustomed to consuming caffeine as part of your daily diet."
Besides waking you up, caffeine also stimulates the brain and improves concentration; there's even evidence that drinking coffee may help you live longer, and even smelling it may relieve stress. But be careful just how much caffeine you're getting and where it's coming from: While black coffee and plain tea have no calories, extras like cream, sugar, and flavored syrupsespecially in large serving sizescan quickly counteract your fitness goals.
Plus, every person reacts to caffeine differently, regardless of dosage. "Don't just assume you will perform better with a caffeine boost: You might just end up nauseated, coping with a ‘coffee stomach,' or suffering from caffeine jitters at a time when you are already nervous and anxious," Clark warns. "Experiment during training to determine if a caffeinated beverage or plain water is your best bet."
A moderate caffeine intake is considered to be about 250 milligrams per day, or two to three cups of coffee daily; most experts agree that a cup or two of java or iced teaan hour before your daily walk, run, or workout sessioncan make the task seem easier.
Is coffee, cola, or tea part of your daily routine? Have you noticed whether caffeine helps fuel your workouts or recovery?
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