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 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.

Study Overview

• Status: Not yet 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 a taurine-caffeine supplementation strategy supports attentional control, efficient visual search, and accurate tactical decision-making under acute neurocognitive load in professional male football players.

Participants will complete familiarization, baseline laboratory testing, baseline field testing, 14 days of supplementation, post-intervention laboratory testing, and post-intervention field testing. The laboratory protocol will include a high-load Stroop/Flanker task followed by a football-specific video decision-making task with screen-based eye-tracking. The video task will include offensive and transitional football situations requiring players to select the most appropriate tactical option under time pressure. Some clips will require inhibition of an immediately attractive but suboptimal forward action.

The primary outcome will be the change in tactical inhibitory decision accuracy under neurocognitive load from baseline to post-intervention. Secondary outcomes will include overall decision accuracy, decision time, impulsive tactical errors, mental fatigue, Stroop/Flanker reaction-time variability, time to first fixation on the optimal option, dwell time on the optimal option, situational awareness accuracy, and field-based reactive passing decision performance. Field-based transfer will be assessed using a Reactive Passing Decision Test, the Loughborough Soccer Passing Test, and standardized small-sided games.

• Study Type: Interventional
• Enrollment (Estimated): 62
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Krzysztof Maciej Mizera, PhD; Phone Number: +48508356718; Email: krzysztofmizera@o2.pl

Study Locations

• Poland
  • Lodz, Poland
    • Professional Football Training Center
    • Contact: Krzysztof Mizera; Phone Number: +48508356718; Email: krzysztofmizera@o2.pl
  • Warsaw, Poland
    • Professional Football Training Center
    • Contact: Krzysztof Mizera, PhD; Phone Number: +48508356718; Email: krzysztofmizera@o2.pl

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 14 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 14 days.
Active Comparator: Taurine Plus Caffeine; Participants randomized to this arm will receive taurine 1500 mg/day plus caffeine 200 mg/day for 14 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 14 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 14 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 14 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
Change in 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 14 days of supplementation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Overall Football-Specific Decision Accuracy	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 14 days of supplementation
Change in 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 14 days of supplementation
Change in Impulsive Tactical Errors	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 14 days of supplementation
Change in Stroop/Flanker Reaction-Time Variability	Reaction-time variability will be assessed during the high-load Stroop/Flanker task used to induce neurocognitive load. The task will assess attentional control, response inhibition, conflict monitoring, and reaction-time stability. The outcome will be expressed in milliseconds.	Baseline and 14 days of supplementation
Change in Post-Task Mental Fatigue	Mental fatigue will be assessed immediately after the neurocognitive load task using a visual analogue scale. The scale will range from 0 to 10, with higher scores indicating greater perceived mental fatigue.	Baseline and 14 days of supplementation
Change in Time to First Fixation on the Optimal Tactical Option	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 14 days of supplementation
Change in Dwell Time on the Optimal Tactical Option	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 14 days of supplementation
Change in 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 14 days of supplementation
Change in Reactive Passing Decision Test 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 14 days of supplementation

Collaborators and Investigators

• Sponsor: Vizja University in Warsaw

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): August 1, 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): July 13, 2026
• Last Update Submitted That Met QC Criteria: July 9, 2026
• Last Verified: July 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