Phosphatidylserine, Taurine, and Caffeine for Cognitive Fatigue in Professional Football Players

This randomized, double-blind, placebo-controlled, parallel-group trial will evaluate the effects of 14 days of taurine-caffeine supplementation with or without phosphatidylserine on neurocognitive fatigue resistance, visual search efficiency, and football-specific tactical decision-making in professional male football players. Sixty-two male outfield football players from two professional clubs will be randomized to placebo, taurine plus caffeine, or taurine plus caffeine plus phosphatidylserine. Laboratory and field-based outcomes will be assessed at baseline and after the supplementation period.

Inclusion Criteria: * Male professional outfield football players aged 18 to 37 years. * First-team players or selected U19 players aged 18 years or older who are regularly integrated into first-team training. * Regular participation in club training. * At least 5 years of systematic football training experience. * Free from injury or illness limiting full participation in training and testing. * Normal or corrected-to-normal vision. * Ability to complete the laboratory and field-based testing procedures. * Written informed consent provided before participation. Exclusion Criteria: * Goalkeepers. * Current injury or illness limiting full participation in testing. * Neurological disease. * Recent concussion or head trauma. * Uncorrected visual impairment. * Use of phosphatidylserine, nootropic agents, or strong stimulants during the previous 4 weeks. * Non-standard caffeine intake on testing days. * Failure to comply with pre-test standardization procedures. * Failed eye-tracker calibration. * Loss of more than 30% of gaze data during the football-specific decision-making task. * Withdrawal of consent.