Impact of Short-Term Caffeine Intake on Beta-Endorphin Levels, EEG Signals, and Exhausting Exercise

The current research aimed to determine the changes in beta-endorphin levels, electroencephalography (EEG) signals, the time to reach drowsiness after a period of short-term caffeine consumption, and a session of stimulant-inducing exercise.

This study was a semi-experimental type, the statistical population of which included female student-athletes of the Shahid Madani University of Azerbaijan, Iran with the age range of 18-24 years, of which 20 were selected purposefully and voluntarily. They were randomly divided into two groups of 10 people, including the athlete group and the placebo group. Both groups participated in the exercise activity and were given capsules—containing either 6 mg/kg of body weight of caffeine or starch—without knowing the contents, one hour before starting the exercise protocol. In both groups, Bruce's training protocol was performed to the point of exhaustion, with the treadmill's incline and speed adjusted in six to seven three-minute stages. Measurements of beta-endorphins, saliva glucose, and EEG activity were taken at three points: half an hour before caffeine consumption, one hour after caffeine consumption, and after completing the exercise test.

The results of this study showed that a session of restorative exercise along with short-term caffeine supplementation in athletes causes significant intra-group changes in the number of delta waves in the prefrontal area of the right hemisphere and the number of beta waves in the frontal area of the left hemisphere. In addition, short-term caffeine supplementation leads to an increase in beta-endorphin levels following a session of residual exercise activity.

Short-term caffeine supplementation by participating in a session of physical activity can improve EEG signals and responses of beta-endorphin values in athletes.