This study will examine whether a 28-day supplementation protocol containing taurine, caffeine, and phosphatidylserine can help professional male football players maintain physical performance, cognitive function, recovery-related readiness, and selected football-specific perceptual-cognitive performance. Participants will be randomly assigned to receive either placebo or a phosphatidylserine-containing multi-ingredient supplement.
Before and after the supplementation period, players will complete non-invasive assessments such as sprint testing, reaction-time testing, heart rate variability monitoring, wellness/readiness questionnaires, mental-fatigue measures, and selected football-specific perceptual-cognitive tasks where available.
The study is designed as an external validation and extension of responder profiles derived from previous randomized controlled trials. Data from previous trials and this validation cohort will be used to examine whether baseline physical, cognitive, autonomic, fatigue-related, recovery-related, or perceptual-cognitive characteristics can predict which players are most likely to benefit from phosphatidylserine-containing multi-ingredient supplementation.
Male professional or highly trained football players aged 18-37 years.
Regular participation in structured football training and team activities.
Minimum of 5 years of structured football training experience.
Regular involvement in club training during the study period.
Current musculoskeletal injury or illness preventing full participation in training or testing.
Musculoskeletal injury within the previous 3 months that may affect sprint, football-specific performance, or perceptual-cognitive testing.
Cardiovascular, metabolic, neurological, psychiatric, or other chronic disease that may affect safety or study outcomes.
Diagnosed sleep disorder.
Parallel
Placebo
Other interventionMatching placebo capsules administered orally once daily for 28 consecutive days. The placebo was matched to the active supplements in appearance, number, packaging, and administration schedule.
Taurine
Dietary supplementTaurine 1500 mg/day administered orally once daily in capsules for 28 consecutive days.
Caffeine
Dietary supplementAnhydrous caffeine 200 mg/day administered orally once daily in capsules for 28 consecutive days.
Phosphatidylserine
Dietary supplementPhosphatidylserine 600 mg/day administered orally once daily in capsules for 28 consecutive days.
Proportion of Participants Classified as Multidimensional Responders After 28 Days
Proportion of participants classified as multidimensional responders after 28 days of supplementation. A multidimensional responder will be defined as a participant meeting the predefined response criterion in at least two of four domains: physical performance/fatigue resistance, cognitive fatigue-related performance, recovery/readiness, and football-specific perceptual-cognitive performance. The outcome will be reported as the percentage of participants classified as multidimensional responders in each group. Unit of Measure: percentage of participants
Change in 30 m Sprint Time
Change in 30 m sprint performance from baseline to post-intervention testing. Sprint time will be measured using electronic timing gates. Participants will perform three maximal 30 m sprint trials separated by standardized recovery periods, and the best valid trial will be used for analysis.
Change in Cognitive Fatigue Task Reaction Time
Change in reaction time during the computerized cognitive fatigue task from baseline to post-intervention testing after 28 days of supplementation. Reaction time will be measured during the predefined cognitive task performed under cognitive load. The outcome will be reported as the mean change in reaction time from baseline to post-intervention testing. Lower values indicate faster cognitive responses. Unit of Measure: milliseconds
Change in Perceived Mental Fatigue VAS Score
Change in perceived mental fatigue from baseline to post-intervention testing after 28 days of supplementation. Perceived mental fatigue will be assessed using a 0-10 visual analogue scale, where 0 indicates no perceived mental fatigue and 10 indicates maximal perceived mental fatigue. The outcome will be reported as the mean change in score from baseline to post-intervention testing. Higher scores indicate greater perceived mental fatigue. Unit of Measure: points on a 0-10 scale
Change in Final 3-Day Mean LnRMSSD
Change in heart rate variability from baseline monitoring to the final 3 days of supplementation. Heart rate variability will be expressed as the natural logarithm of the root mean square of successive RR interval differences. Morning HRV will be recorded under standardized resting conditions. The outcome will be reported as the mean change in final 3-day mean LnRMSSD compared with the baseline monitoring period. Unit of Measure: ln(ms)
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