Caffeine increases high-intensity exercise performance! In the past year alone, research has shown that the consumption of just two cups of coffee can speed 1500-metre running performances by four seconds and increase kicking speeds at the ends of 1500-metre races by 3 per cent. Other investigations have indicated that caffeine can boost 100-metre swimming velocity and enhance sprinting ability on a bicycle. Finally, an interesting recent study demonstrated that caffeine - when taken DURING exercise - does not increase an athlete's risk of dehydration, as had been previously believed.

Now, a new piece of research shows that caffeine can enhance the quality of interval workouts. At the University of Guelph in Canada, 14 athletes completed two separate interval workouts, once under the influence of caffeine and once with a placebo. The actual pre-workout caffeine dosage was 6 milligrams per kilogram of body weight, or about the amount in three to four cups of strong coffee. The workout itself consisted of two minutes of exercise at 100% V02max (about the intensity of a two-mile running race), followed by six minutes of recovery, two minutes at 100% V02max, six minutes of recovery, and then a final interval at 100% V02max for as long as the athletes could continue exercising.

Following caffeine ingestion, the subjects were able to exercise for 20-per cent longer during the final interval (4.93 minutes versus 4.12 minutes). The reasons for the caffeine-related enhancement weren't exactly clear, although caffeine did boost blood adrenaline levels and also seemed to increase anaerobic energy production. Adrenaline can increase the power of muscle contractions, and a spike in anaerobic energy creation permits athletes to exercise at high levels for longer periods of time. It's also possible that caffeine may decrease mental fatigue during strenuous exertions.

When combined with other recent research, the Guelph study shows that our traditional notions about caffeine should be discarded. Once viewed as a drug which could boost endurance performances because of its possible ability to stimulate fat metabolism, caffeine has now emerged as a chemical which aids sprint - not endurance - performances. Sprint athletes must be very careful, however; ingesting the amount of caffeine in six or more cups of coffee can easily cause them to fail a doping test.

The bottom line? Endurance athletes can toss aside their pre-race cups of coffee and caffeine suppositories, but shott-distance competitors (those who compete in events lasting five minutes or less) who swill a couple of cups of brew about an hour before they race will probably perform at a higher level.