Caffeine Does Not Affect Improvements in Cognition During Prolonged High-Intensity Exercise in Alert Well-Trained Individuals

Abstract

Background:

Recent research has demonstrated improvements in cognitive function during bouts of high-intensity endurance exercise. Caffeine, the most commonly used ergogenic aid in the world, can improve cognition both at rest and during exercise and can also improve exercise performance during simulated cycling races.

Purpose:

To determine if caffeine ingestion in conjunction with prolonged high-intensity exercise can synergistically improve cognitive function, and whether the type of exercise trial affects the cognitive response.

Methods:

Seven well-trained cyclists and triathletes (26.9 ± 3.9 years, VO₂ peak 67.7 ± 10.3 mL/kg/h) completed two trials to exhaustion (TTE) at 90% VO₂ peak and two 50 km time trials (TTD), 1 hour after consuming a carbohydrate–electrolyte beverage (5 mL/kg, 6.3% CHO, 18 mM sodium) and a capsule containing either 6 mg/kg of caffeine or a placebo (double-blind crossover design). A second CHO beverage was consumed at the onset of each trial. Cognitive function was measured before and after exercise using a computerized ANAM^® test and Stroop word–color test (also conducted during exercise).

Results:

Average wakefulness scores at baseline indicated that subjects were at near peak alertness. Caffeine ingestion did not influence exercise performance, ANAM thruput scores, or Stroop word–color test response times in either trial type. However, exercise significantly improved ANAM and Stroop cognitive results, regardless of exercise trial.

Conclusion:

In alert well-trained athletes, high-intensity endurance exercise can significantly improve tests of simple and complex cognitive function. Neither exercise trial type nor caffeine ingestion impacts the exercise-induced changes in cognitive function.