This randomized double-blind placebo-controlled trial will investigate the effects of multi-ingredient supplementation containing taurine, caffeine, and phosphatidylserine on physical performance, cognitive function, cognitive fatigue responses, recovery, sleep quality, and autonomic nervous system activity in elite male soccer players. Participants will complete a 14-day supplementation protocol and undergo football-specific performance, reaction-time, cognitive-fatigue, recovery, and sleep-related assessments before and after the intervention. The study aims to determine whether phosphatidylserine dose influences physical, cognitive, fatigue-related, and recovery-related outcomes when combined with taurine and caffeine.
The planned study will be a randomized, double-blind, placebo-controlled trial designed as a continuation and extension of previous research on multi-ingredient supplementation in professional football players. The primary aim will be to investigate the dose-dependent effects of phosphatidylserine combined with taurine and caffeine under standardized football-specific training conditions and acute cognitive-fatigue conditions. Approximately 80 professional male football players competing at national level will be randomly assigned to four groups: placebo, taurine + caffeine, taurine + caffeine + phosphatidylserine 300 mg, and taurine + caffeine + phosphatidylserine 600 mg. Importantly, caffeine and taurine doses will remain identical across all active supplementation groups in order to enable a more precise evaluation of the independent effects of phosphatidylserine. Participants will complete a 14-day supplementation protocol and undergo baseline and post-intervention assessments including 30 m sprint performance, reaction time, cognitive-fatigue responses, football-specific GPS monitoring, fatigue-related performance decline, recovery-related variables, sleep monitoring, and autonomic nervous system activity assessment. The study is expected to provide novel insights into the role of phosphatidylserine in football-specific performance, cognitive fatigue resistance, recovery, and neurophysiological responses in elite football players.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
97
Placebo capsules administered daily during the 14-day intervention period
Taurine supplementation administered daily during the 14-day intervention period.
Caffeine supplementation administered daily during the 14-day intervention period.
Phosphatidylserine supplementation administered daily during the 14-day intervention period.
Professional Football Training Center
Budapest, Hungary
Professional Football Training Center
Lodz, Poland
Professional Football Training Center
Warsaw, Poland
Professional Football Training Center
Wroclaw, Poland
Professional Football Training Center
Alicante, Spain
30 m sprint time
Time required to complete a 30 m sprint, measured using electronic timing gates. The best result from three maximal sprint trials will be used for analysis. Unit of Measure: seconds
Time frame: Baseline and after 14 days of supplementation
Change in sprint count between first and second half
Percentage decline in the number of sprints between the first and second half of the standardized football-specific training session. Sprint change will be calculated as: \[(second half value - first half value) / first half value\] × 100. Unit of Measure: percent
Time frame: After 14 days of supplementation, during the standardized football-specific training session
Visual reaction time
Mean response time to a visual stimulus, measured using a validated visual reaction time test.
Time frame: Baseline and after 14 days of supplementation
Auditory reaction time
Mean response time to an auditory stimulus, measured using a computerized auditory reaction time test.
Time frame: Baseline and after 14 days of supplementation
Total distance covered
Total distance covered during the standardized football-specific training session, measured using a 10-Hz GPS tracking system. Unit of Measure: meters
Time frame: After 14 days of supplementation, during the standardized football-specific training session
Relative distance
Distance covered per minute during the standardized football-specific training session, measured using a 10-Hz GPS tracking system. Unit of Measure: meters per minute
Time frame: After 14 days of supplementation, during the standardized football-specific training session
High-speed running distance
Description: Distance covered at running speeds above 19.8 km/h during the standardized football-specific training session, measured using a 10-Hz GPS tracking system. Unit of Measure: meters
Time frame: After 14 days of supplementation, during the standardized football-specific training session
Number of sprints
Total number of sprint efforts performed during the standardized football-specific training session. Sprinting will be defined as running speed above 25.0 km/h and measured using a 10-Hz GPS tracking system. Unit of Measure: number of sprints
Time frame: After 14 days of supplementation, during the standardized football-specific training session
Player Load
External training load during the standardized football-specific training session, measured using triaxial accelerometry integrated with the GPS tracking system. Unit of Measure: arbitrary units
Time frame: After 14 days of supplementation, during the standardized football-specific training session
Heart rate variability RMSSD
Resting heart rate variability assessed in the morning using the root mean square of successive differences between normal heartbeats. HRV will be measured using a heart rate sensor or wearable device under standardized resting conditions. Unit of Measure: milliseconds
Time frame: Daily during the 14-day supplementation period
Sleep duration
Total sleep duration assessed using wearable sleep monitoring. Unit of Measure: hours
Time frame: Daily during the 14-day supplementation period
Sleep efficiency
Percentage of time in bed spent asleep, assessed using wearable sleep monitoring. Unit of Measure: percent
Time frame: Daily during the 14-day supplementation period
Subjective fatigue
Subjective fatigue assessed using the fatigue item of the Hooper Index questionnaire on a 1-7 scale, where higher values indicate greater fatigue. Unit of Measure: score on a scale
Time frame: Daily during the 14-day supplementation period
Muscle soreness
Perceived lower-limb muscle soreness assessed using a 0-10 delayed onset muscle soreness scale, where higher values indicate greater soreness. Unit of Measure: score on a scale
Time frame: Daily during the 14-day supplementation period
Stroop task reaction time
Mean response time during a modified computerized Stroop task assessing cognitive fatigue, inhibitory control, sustained attention, and information processing speed. Unit of Measure: seconds
Time frame: Baseline and after 14 days of supplementation
Stroop task accuracy
Percentage of correct responses during a modified computerized Stroop task. Unit of Measure: percent
Time frame: Baseline and after 14 days of supplementation
Stroop task error rate
Number of incorrect responses during a modified computerized Stroop task. Unit of Measure: number of errors
Time frame: Baseline and after 14 days of supplementation
Perceived mental fatigue
Subjective perceived mental fatigue assessed using a 0-10 visual analogue scale, where higher values indicate greater perceived mental fatigue. Unit of Measure: score on a 0-10 scale
Time frame: Baseline and after 14 days of supplementation
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