Effects of caffeine supplementation and time trial protocol on cognitive function and exercise performance
Pollow, Dennis Paul, Jr.
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Background. Evidence suggests that caffeine can act as an ergogenic aid during endurance exercise. While caffeine ingestion has been shown to improve cycling performance times in time trial races and exhaustive exercise, few studies have measured for cognitive function improvements during these tests. Purpose. (1) To determine if caffeine ingestion can affect cognitive function and exercise performance outcomes during prolonged intense cycling and (2) To determine if the type of exercise trial can alter the effects of caffeine. Methods. Seven well-trained cyclists and triathletes completed two 50k time trials and two trials to exhaustion at 90% VO 2 peak on a computrainer pro cycle ergometer, one hour after consuming a carbohydrateelectrolyte beverage (5ml/kg, 6.3% CHO, 18mmol/l sodium) and a capsule containing 6 mg/kg caffeine (CAF) or placebo (PLA). Cognitive function was measured before and after exercise by a computerized ANAM® test and a Stroop word-color test (also conducted during exercise). Results. ANAM thruput scores significantly improved with all exercise trials, but were not altered by the addition of caffeine (P < 0.001). Subjects were significantly faster after exercise on the Stroop word-color test, with no trade-off in accuracy (P < 0.0001). CAF did not significantly change exercise performance in the 50k time trial or time to exhaustion trials. However, subjects were able to cycle significantly farther during their second TTE trial compared to the first (P < 0.001). Conclusion. In well trained athletes, high intensity endurance exercise can significantly improve simple and complex cognitive function, but is not enhanced with the addition of caffeine. The type of exercise trial does not alter the exercise-induced changes in cognitive function.