Phosphatidylserine, Taurine, and Caffeine for Cognitive Fatigue in Professional Football Players (TCPS-Foot)

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

This randomized, double-blind, placebo-controlled, parallel-group trial will evaluate 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-two male outfield football players from two professional clubs will be randomized to placebo, taurine plus caffeine, or taurine plus caffeine plus phosphatidylserine. Neurocognitive fatigue resistance will be evaluated during a standardized high-load Stroop/Flanker task, while football-specific tactical decision-making, visual-search behavior, and field-based reactive decision performance will be assessed at baseline and after 28 days of supplementation.

Study Overview

• Status: Active, not recruiting
• Conditions: Mental Fatigue; Athletic Performance; Cognitive Performance; Decision Making; Soccer Performance
• Intervention / Treatment: Dietary supplement: Placebo; Dietary supplement: Taurine Plus Caffeine; Dietary supplement: Taurine, Caffeine, and Phosphatidylserine

Detailed Description

This study is 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 will complete familiarization procedures, baseline laboratory and field testing, 28 days of supplementation, and post-intervention laboratory and field testing. Neurocognitive fatigue resistance will be assessed using a standardized high-load Stroop/Flanker protocol. Football-specific decision-making will be 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 will be assessed using screen-based eye tracking during the football-specific decision task. Field-based reactive decision performance will be evaluated using a standardized football-specific test requiring perception of an external stimulus followed by an appropriate movement response. Outcome assessments will be conducted before and after the 28-day supplementation period under standardized testing conditions.

• Study Type: Interventional
• Enrollment (Estimated): 65
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Poland
  • Lodz, Poland
    • Professional Football Training Center
  • Warsaw, Poland
    • Professional Football Training Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo; Participants randomized to this arm will receive an inert placebo for 28 days. The placebo will be provided in identical coded packs matched for appearance, number of units, and packaging with the active supplements.	Dietary supplement: Placebo; Inert placebo matched with the active supplements for appearance, number of units, and packaging. The placebo will be administered for 28 days.
Active Comparator: Taurine Plus Caffeine; Participants randomized to this arm will receive taurine 1500 mg/day plus caffeine 200 mg/day 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.	Dietary supplement: Taurine Plus Caffeine; 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.
Experimental: Taurine, Caffeine, and Phosphatidylserine; Participants randomized to this arm will receive taurine 1500 mg/day plus caffeine 200 mg/day plus phosphatidylserine 600 mg/day 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.	Dietary supplement: Taurine, Caffeine, and Phosphatidylserine; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tactical Inhibitory Decision Accuracy Under Neurocognitive Load	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.	Baseline and 28 days of supplementation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Football-Specific Optimal Decision Rate	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.	Baseline and 28 days of supplementation
Football-Specific Decision Time	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.	Baseline and 28 days of supplementation
Impulsive Tactical Error Rate	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.	Baseline and 28 days of supplementation
Stroop/Flanker Time-on-Task Reaction-Time Trajectory	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.	Baseline and 28 days of supplementation
Stroop/Flanker Reaction-Time Variability	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.	Baseline and 28 days of supplementation
Post-Task Mental Fatigue	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.	Baseline and 28 days of supplementation
Time to First Fixation on the Optimal Tactical Area of Interest	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.	Baseline and 28 days of supplementation
Dwell Time on the Optimal Tactical Area of Interest	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.	Baseline and 28 days of supplementation
Situational-Awareness Accuracy	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.	Baseline and 28 days of supplementation
Reactive Passing Decision-Selection Accuracy	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.	Baseline and 28 days of supplementation

Collaborators and Investigators

• Sponsor: Vizja University in Warsaw
• Collaborators: Józef Piłsudski University of Physical Education

Study record dates

Study Major Dates

• Study Start (Actual): August 6, 2026
• Primary Completion (Actual): August 10, 2026
• Study Completion (Estimated): September 7, 2026

Study Registration Dates

• First Submitted: July 5, 2026
• First Submitted That Met QC Criteria: July 5, 2026
• First Posted (Actual): July 10, 2026

Study Record Updates

• Last Update Posted (Actual): September 9, 2026
• Last Update Submitted That Met QC Criteria: September 2, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Keywords: Soccer; Phosphatidylserine; Caffeine; Eye Tracking; Taurine; Visual Search; Football Players; Sports Nutrition; Neurocognitive Load; Tactical Decision-Making; Stroop Flanker Task; Reactive Passing Decision Test
• Additional Relevant MeSH Terms: Behavioral Symptoms; Fatigue; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Mental Fatigue; Sulfur Compounds; Organic Chemicals; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Lipids; Hydrocarbons, Acyclic; Hydrocarbons; Alkaloids; Purinones; Purines; Alkanes; Alkanesulfonic Acids; Sulfonic Acids; Sulfur Acids; Membrane Lipids; Xanthines; Glycerophospholipids; Phosphatidic Acids; Glycerophosphates; Phospholipids; Caffeine; Taurine; Phosphatidylserines
• Other Study ID Numbers: MIZERA -4-TCPS-FOOT-2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No individual participant data will be shared because the study includes a small sample of professional football players from a limited number of clubs, which may increase the risk of indirect participant identification. Only aggregated and anonymized study results will be reported.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No