Caffeine, a popular natural stimulant, has been consumed around the world for centuries, in the forms of tea and coffee and, more recently, in soft drinks and energy drinks. The average American consumes the equivalent of two to three cups of coffee per day. Scientific research has revealed some benefits of moderate caffeine consumption; some studies show that caffeine improves athletic performance.
Caffeine may increase athletic performance by delaying fatigue, according to a study published in the May 2010 issue of "European Journal of Applied Physiology." In the study, highly trained cyclists exercised to exhaustion after consuming 5 mg of caffeine per kilogram of body weight. Caffeine consumption resulted in significant increases in the length of time the cyclists were able to exercise. The amount of oxygen the athletes used was not increased, compared to exercising without caffeine; however, the researchers noted that levels of potassium were reduced by 13 percent with the caffeine consumption prior to exercising. They concluded that altered levels of potassium may have contributed to the improved endurance in the study participants.
Caffeine increases respiratory function and may have either a beneficial or detrimental effect on exercise performance, according to a study published in the December 2009 issue of "The Physician and Sportsmedicine." Caffeine has a strong stimulatory effect on the respiratory system in both trained and untrained people, increasing respiratory functions in endurance athletes and improving nervous system feedback in nonathletes. Its anti-inflammatory and bronchial protective effects make caffeine useful as a treatment for asthma, say the researchers, and its widespread use has increased its acceptance among international sports-doping-control agencies.
A study published in the January 2011 issue of "European Journal of Applied Physiology" found that caffeine, together with creatine, a supplement that improves energy supply in muscles, improved high-intensity sprint performance. In the study, cyclists took, for 5 days, 0.3 g of creatine per kilogram of body weight and 6 mg of caffeine per kilogram of body weight. The performance test consisted of six 10-second high-intensity sprints, separated by 1-minute rest periods. In the first two sprints, the creatine-with-caffeine group showed significantly higher maximal power than the creatine-only group. In most of the sprints, heart rates and blood sugar increased significantly with the combination supplement.
Consuming caffeine with carbohydrates improves cardiovascular performance in athletes, according to a study published in the June 2010 issue of "Journal of Sports Science." In the study, rugby players consumed 1.2 g of carbohydrate per kilogram of body weight and 4 mg of caffeine per kilogram of body weight prior to exercising. The test exercise consisted of a combination of activities that included high- and low-intensity exercises. Carbohydrate and caffeine together improved sprinting time and motor skills. The athletes' ratings of their perceived effort was lower in the combination supplement group. The researchers concluded that carbohydrate with caffeine improved performance, including cardiovascular function, in rugby players.