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Completed

NCT Number: NCT07696052

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

This randomized, double-blind, placebo-controlled, parallel-group trial evaluated neurocognitive fatigue resistance and football-specific decision-making following 28 days of taurine-caffeine supplementation with or without phosphatidylserine in professional male football players. Sixty-five male outfield football players from two professional clubs were randomized to placebo, taurine plus caffeine, or taurine plus caffeine plus phosphatidylserine. Neurocognitive fatigue resistance was evaluated during a standardized high-load Stroop/Flanker task, while football-specific tactical decision-making, visual-search behavior, and field-based reactive decision performance were assessed at baseline and after 28 days of supplementation.

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Key information

Conditions

Mental Fatigue Athletic Performance Behavior Behavioral Symptoms Cognitive Performance Decision Making Fatigue Pathological Conditions, Signs and Symptoms Signs and Symptoms Soccer Performance

Age range

18 year–37 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Professional Football Training Center, Lodz, Poland

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About this study

This study was designed to determine whether adding phosphatidylserine to taurine-caffeine supplementation improves neurocognitive fatigue resistance and football-specific decision-making in professional male football players. Participants completed familiarization procedures, baseline laboratory and field testing, 28 days of supplementation, and post-intervention laboratory and field testing. Neurocognitive fatigue resistance was assessed using a standardized high-load Stroop/Flanker protocol. Football-specific decision-making was evaluated using video-based tactical decision tasks incorporating offensive and transitional match situations and requiring rapid selection of the most appropriate tactical response. Visual-search behavior was assessed using screen-based eye tracking during the football-specific decision task. Field-based reactive decision performance was evaluated using a standardized Reactive Passing Decision Test requiring perception of an external visual stimulus followed by selection and execution of the appropriate passing response. Outcome assessments were conducted before and after the 28-day supplementation period under standardized testing conditions.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Placebo

Dietary Supplement

Inert placebo matched with the active supplements for appearance, number of units, and packaging. The placebo will be administered for 28 days.

Taurine Plus Caffeine

Dietary Supplement

Taurine 1500 mg/day plus caffeine 200 mg/day administered for 28 days. On training and testing days, the supplement will be consumed approximately 60 minutes before the main training session or testing procedure. On non-training days, it will be consumed at a consistent morning time.

Taurine, Caffeine, and Phosphatidylserine

Dietary Supplement

Taurine 1500 mg/day plus caffeine 200 mg/day plus phosphatidylserine 600 mg/day administered for 28 days. On training and testing days, the supplement will be consumed approximately 60 minutes before the main training session or testing procedure. On non-training days, it will be consumed at a consistent morning time.

Primary outcomes

  1. Tactical Inhibitory Decision Accuracy Under Neurocognitive Load

    Time frame: Baseline and 28 days of supplementation

    Tactical inhibitory decision accuracy will be assessed using football-specific video clips requiring inhibition of an immediately attractive but suboptimal tactical action. Responses will be scored as 1 point for an optimal decision, 0.5 points for an acceptable decision, and 0 points for an incorrect decision. The outcome will be calculated as the mean score across inhibitory tactical clips. The score ranges from 0 to 1, with higher values indicating better tactical inhibitory decision accuracy.

Secondary outcomes

  1. Overall Football-Specific Optimal Decision Rate

    Time frame: Baseline and 28 days of supplementation

    Overall football-specific decision accuracy will be assessed using video-based offensive and transitional football situations. Players will select the most appropriate tactical option under time pressure. The outcome will be expressed as the percentage of correct or expert-rated optimal decisions, with higher values indicating better decision-making accuracy.

  2. Football-Specific Decision Time

    Time frame: Baseline and 28 days of supplementation

    Decision time will be assessed during the football-specific video decision-making task. It will be measured as the time taken to select a tactical response after the critical decision point. The outcome will be expressed in milliseconds, with lower values indicating faster decision-making.

  3. Impulsive Tactical Error Rate

    Time frame: Baseline and 28 days of supplementation

    Impulsive tactical errors will be assessed during football-specific video clips. These errors will include selections of immediately attractive but suboptimal tactical options, such as inappropriate forward actions, low-quality shots, or forced progressive decisions when a safer or more appropriate option is available.

  4. Stroop/Flanker Time-on-Task Reaction-Time Trajectory

    Time frame: Baseline and 28 days of supplementation

    Correct-trial reaction time will be assessed across six consecutive 5-minute epochs of the 30-minute high-load Stroop/Flanker task. Time-on-task performance decrement will be quantified from the within-session trajectory of reaction time across successive epochs, with a greater increase in reaction time indicating greater neurocognitive performance deterioration and a smaller increase indicating greater neurocognitive fatigue resistance. Response accuracy across epochs will be reported as a complementary measure.

  5. Stroop/Flanker Reaction-Time Variability

    Time frame: Baseline and 28 days of supplementation

    Reaction-time variability will be assessed during the 30-minute high-load Stroop/Flanker task. It will be quantified from valid correct-trial reaction times as a within-participant measure of response-time variability and expressed in milliseconds, with greater variability indicating lower response stability.

  6. Post-Task Mental Fatigue

    Time frame: Baseline and 28 days of supplementation

    Perceived mental fatigue will be assessed immediately before and immediately after the 30-minute neurocognitive-load task using a 0-10 numerical rating scale, with higher scores indicating greater perceived mental fatigue. The registered outcome will be the post-task mental-fatigue score assessed at baseline and after 28 days of supplementation. The acute pre-to-post task change will additionally be used as a manipulation check of the neurocognitive-load protocol.

  7. Time to First Fixation on the Optimal Tactical Area of Interest

    Time frame: Baseline and 28 days of supplementation

    Time to first fixation on the optimal tactical option will be assessed using screen-based eye-tracking during the football-specific video decision-making task. The outcome will be expressed in milliseconds and will reflect how quickly the player visually orients toward the expert-defined optimal option.

  8. Dwell Time on the Optimal Tactical Area of Interest

    Time frame: Baseline and 28 days of supplementation

    Dwell time on the optimal tactical option will be assessed using screen-based eye-tracking during the football-specific video decision-making task. The outcome will be expressed as the percentage of total viewing time spent fixating on the expert-defined optimal tactical option.

  9. Situational-Awareness Accuracy

    Time frame: Baseline and 28 days of supplementation

    Situational awareness accuracy will be assessed using probes presented after selected football-specific video clips. These probes will evaluate whether players correctly identified key tactical information, including available space, pressure location, number of defenders, teammate positioning, and defensive-line configuration.

  10. Reactive Passing Decision-Selection Accuracy

    Time frame: Baseline and 28 days of supplementation

    Reactive Passing Decision Test accuracy will be assessed during a field-based football-specific task. Players will dribble into a decision zone and respond to a late visual or situational cue by selecting and executing the optimal passing option. The outcome will be expressed as the percentage of accurate decisions.

Sponsors and collaborators

Lead sponsor

Vizja University in Warsaw

Other

Collaborators

  • Józef Piłsudski University of Physical Education

Registry information

Official study title

Neurocognitive Fatigue Resistance, Visual Search Efficiency, and Tactical Decision-Making After Phosphatidylserine-Containing Taurine-Caffeine Supplementation in Professional Male Football Players

Acronym: TCPS-Foot

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jul 10, 2026
Registry last updated
Sep 14, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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