Caffeine is a popular preexercise energizer and is known to help athletes train harder and longer. Caffeine stimulates the brain and contributes to clearer thinking and greater concentration. There are many good studies on the use of caffeine for both endurance exercise, such as long runs and bike rides, and short-term, higher-intensity exercise, such as soccer. The vast majority of the studies conclude that caffeine does indeed enhance performance (by about 11 percent) and makes the effort seem easier (by about 6 percent). Endurance athletes notice more benefits than those who do shorter bouts of exercise (Doherty and Smith 2005).
If you rarely drink coffee, you may notice a dramatic caffeine boost because you are not tolerant to caffeine's stimulant effect. A study comparing regular caffeine users to nonusers reports that the nonusers lasted eight and a half minutes longer when biking very hard to exhaustion, as compared with when they had no preexercise caffeine. The regular caffeine users exercised for only four minutes longer when they had the caffeine fix (Bell and McLellan 2002).
Because each person responds differently to caffeine, do not 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. And be forewarned: Although a morning cup of coffee can assist with a desirable bowel movement, a precompetition mugful might lead to transit troubles. Experiment during training to determine if a caffeinated beverage or plain water is your best bet.
But doesn't caffeine have a dehydrating effect? According to Dr. Larry Armstrong, an exercise physiologist at the University of Connecticut, caffeine does not contribute to excessive water loss and is OK for athletes, even in hot weather (Armstrong 2002). The military became intensely interested in the physiological effects of caffeine on hydration among soldiers enduring extreme heat. They researched the effects of moderate (approximately 200 mg) and high (approximately 400 mg) doses of caffeine on hydration in soldiers who habitually consumed only one 6-ounce (175 ml) cup of brewed coffee (100 mg caffeine per day). They found no detrimental effects of caffeine. By day's end, the 24-hour urine losses were similar (Armstrong et al. 2005). In another study testing endurance in hot weather (100 degrees Fahrenheit; 37.7 degrees Celsius), the subjects who consumed about 225 milligrams of caffeine—the equivalent of a 12-ounce (355 ml) mug of coffee—exercised for 11 minutes longer (86 versus 75 minutes) compared with the group who had no caffeine (Roti et al. 2006).
Although a cup or two of coffee before exercise may be a helpful ener-gizer, more may be of little value. A 1995 study (Pasman et al. 1995) showed that well-trained cyclists performed equally well with about 350 milligrams of caffeine as they did with 850 milligrams. So if you're tempted to jazz yourself up with a second mugful, think again. You may find that the second mug will do you in with the caffeine jitters. Small doses of caffeine (such as taken socially) may enhance performance, whereas high doses can be counterproductive to performance. A target dose is about 1.5 milligrams per pound (3 milligrams per kilogram)
(Doherty and Smith 2005). For a 150-pound (68 kg) athlete, this comes to about 225 milligrams of caffeine. Table 9.1 lists the caffeine amounts in some common perk-me-ups.
Table 9.1 Caffeine Sources
Brewed, drip method, generic 265 (200-400)
Starbucks brewed, grande 320
Dunkin' Donuts 200
Decaffeinated 10 (6-24) Other beverages
Starbucks espresso, doppio (6.5 oz) 150
Starbucks Tazo Chai Tea Latte, 16 oz (480 ml) 100
Snapple Lemon Tea, 16 oz (480 ml) 42
Snapple Peach Tea, 16 oz (480 ml) 42
Snapple Plain Tea, 16 oz (480 ml) 18 Soft drink, 12 oz (360 ml) can*
Mountain Dew, regular or diet 71
Pepsi One 54
Mello Yello, regular or diet 53
Diet Pepsi 36
Coca-Cola, classic or diet 35
Barq's Root Beer 23 Energy drinks
Rockstar Energy Drink, 8 oz (240 ml) 80 Caffeinated sports supplements
Jolt gum, 1 piece 35
NoDoz, maximum strength, 1 tablet 200
Dexatrim, 1 tablet 80
Excedrin, 1 tablet 65
Anacin, 1 tablet 32
*Small children who drink a can of cola can receive the equivalent in caffeine to an adult who drinks a cup of coffee. Copyright CSPI 2007. Adapted from Nutrition Action Healthletter. www.cspinet.org
Many people drink a warm mug of coffee not for an energy boost but because a warm liquid promotes regular bowel movements and helps empty them out before they exercise. This may be the most justifiable reason for some people to include this brew in their preexercise diet. After all, if you are so tired that you seek coffee for its stimulant effect, you should probably be resting and not dragging yourself through a workout. Be sure no trouble is brewing in your desire for caffeine!
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