I stopped drinking coffee regularly about a year ago. The result is that now, whenever I sip even the tiniest cup, I feel a dramatic bounce in my step. Tea has the same effect. A year's worth of deprivation might not be worth it for everyone, but I can't recommend it enough for giving a boost to the workout regimen on those days when you want to improve on your personal best.
When I am racing, I want to be as sensitive to the caffeine as possible. I choose decaf on a daily basis when I am training, and then, on race day, drink a cup of the real thing. Double-blind studies show that coffee decreases the amount of time it takes to run 1,500 metres, and decreases perceived exertion. It also increases the speed of the "finishing burst" at the end of a sprint and improves recovery times. It's a wonder it hasn't been banned in professional sports as a performance enhancer.
But do the positive effects of caffeine - that jolt of energy and reduced lactate build-up in the muscles - outweigh the negative effects? If you drink too much of it and your body's not used to it, you may experience an increase in dehydration and an upset stomach, especially if it is consumed on an empty stomach. There is also the dependence issue, if, for example, one started to think that every day was worthy of race-day results.
I've found that the dose is important, and it's easier to control with tea bags. Lightly steeped tea gives a gentler boost to the nervous system than a shot of espresso. Caffeine is an agent chemically similar to one used in asthma treatments. In some cases, it can help improve short-term lung function. A recent study by researchers at Indiana University showed that drinking caffeine within an hour of exercise was as effective as using an albuterol inhaler to reduce symptoms of exercise-induced asthma. The most effective dose was nine milligrams of caffeine per kilogram of body weight - that's about 610mg for someone weighing 68kg, which is a very large dose. That would be equivalent to drinking seven Red Bulls or six shots of espresso. Smaller amounts of caffeine, for example 3mg per kilogram of body weight, also reduced the wheezing and coughing. That's about three cups of tea - more manageable, but still likely to send my heart rate through the roof.
Researchers have been investigating the efficacy of a number of nutritional factors on exercise-induced asthma, and found that a diet high in fish oil and antioxidants and low in salt can also reduce symptoms. Since there is growing concern about the potential side effects of long-term inhaled corticosteroid use, finding new solutions is an important undertaking.