Oliveira, M., Hogervorst, E., Gleeson, M., Bandelow, S., & Schmitt, J. (2008). The effects of caffeine on cognitive performance during and following prolonged exercise to exhaustion. ACSM 55th Annual Meeting Indianapolis, Presentation Number 2041.

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This study investigated the effects of ingesting a cereal bar containing caffeine before and during cycling exercise on physical and cognitive performance. Well-trained cyclists (N = 24) consumed supplements: 1) a cereal bar containing 45 g carbohydrate, 3 g fat, 5 g protein, and 4 g fiber with 100 mg caffeine, 2) an isocaloric non caffeine cereal bar control, or 3) 300 ml of placebo beverage at rest and performed 2.5 hours of exercise at 60%VO2max. Additional supplements were taken after 55 and 115 minutes of exercise. During exercise, measurements of respiratory gas exchange, heart rate, rating of perceived exertion, and blood glucose were made every 20 minutes. Cognitive function measures (computerized Stroop and Rapid Visual Information Processing tests) were performed at rest, before exercise, and at 70 and 140 minutes in the exercise. At the end of the 2.5 hours of exercise, Ss were given a 5-minute break, immediately followed by a time-to-exhaustion trial at 75%VO2max. The same physiological and cognitive measurements were obtained five minutes after completing the exhaustion ride.

Ss were significantly faster after caffeine when compared to the control condition on the computerized complex information processing tests, particularly after 140 minutes of exercise and after the exhaustion-ride. For the placebo beverage trial, performance was significantly slower than after the other treatments. The exhaustion ride was longer after caffeine consumption compared with the control and beverage trials and longer after the control condition than after the beverage condition. No differences were found in the RPE, mean heart rate, and relative exercise intensity. Blood glucose concentration was lower in the beverage trial compared to both caffeine and control trials.

Implication. Caffeine in a cereal bar can significantly improve complex cognitive ability during and after strenuous exercise. These effects are strong after exercise to fatigue and may be important for sports performance in which concentration plays a major role.

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