Effects of L-Tyrosine and Caffeine on Performance in Elite Boxers
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Placebo, L-Tyrosine, Caffeine, L-tyrosine + Caffeine.
- Who it may be relevant to
- Registry conditions: Sports Performance. Basic parameters: from 18 years · Male.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Turkey (Türkiye)
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Effects of L-Tyrosine and Caffeine Supplementation on Cognitive, Physical, and Physiological Parameters in Elite Boxers: A Randomized Double-Blind Placebo-Controlled Crossover Study
Overview
Participants will complete six sessions, including one familiarization and baseline session followed by five experimental conditions: control (no supplementation), placebo, L-tyrosine, caffeine, and combined L-tyrosine plus caffeine. The experimental conditions will be performed in a randomized, counterbalanced crossover design with a washout period of at least 72 hours between sessions. Resting physiological and cognitive assessments will be performed during the familiarization session, while biochemical, cognitive, and boxing-specific performance assessments will be conducted before and after each experimental session.
Detailed description
Participants will attend six sessions in total. The first session will be used for familiarization and baseline assessments, including anthropometric measurements, resting physiological measurements, and cognitive performance testing. The remaining five sessions will consist of one control condition (no supplementation) and four randomized experimental conditions (placebo, L-tyrosine, caffeine, and combined L-tyrosine plus caffeine) administered in a randomized, counterbalanced crossover design.
Each experimental session will be separated by a washout period of at least 72 hours. During the placebo, L-tyrosine, caffeine, and combined supplementation conditions, the assigned intervention will be administered 60 minutes before exercise. No supplement will be administered during the control condition.
Before and immediately after each experimental session, venous blood samples will be collected to assess brain-derived neurotrophic factor (BDNF) and oxidative stress biomarkers, including total antioxidant status (TAS), total oxidant status (TOS), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx). Cognitive performance will be evaluated using the computerized Stroop test, and boxing-specific physical performance will be assessed using a standardized boxing simulation protocol. Heart rate and rating of perceived exertion (RPE) will also be recorded during the exercise protocol.
Interventions
- Dietary supplement Placebo
Placebo solution matched in taste and volume to active supplements. - Dietary supplement L-Tyrosine
L-tyrosine at 150 mg/kg body weight administered 60 minutes before exercise. - Dietary supplement Caffeine
Caffeine at 5 mg/kg body weight administered 60 minutes before exercise. - Dietary supplement L-tyrosine + Caffeine
Combined L-tyrosine (150 mg/kg) and caffeine (5 mg/kg) administered 60 minutes before exercise.
Primary outcome measures
- Stroop Test Performance [Time frame: up to 12 weeks]
Secondary outcome measures (2)
- BDNF Levels [Time frame: up to 12 weeks]
- Oxidative Stress Markers [Time frame: up to 12 weeks]
Eligibility criteria
Inclusion criteria
Male elite boxers aged ≥18 years At least 8 years of boxing training experience Active participation in national or international competitions Regular training schedule No injury or illness affecting performance
Exclusion criteria
Use of nutritional supplements or stimulants within the last 4 weeks Any cardiovascular, metabolic, or neurological disorder Current injury or musculoskeletal limitation Smoking or excessive caffeine intake Failure to comply with study procedures
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Double blind
- Primary purpose
- Basic science
Study locations
Turkey (Türkiye) · 1 center
- Ataturk University Faculty of Sport Sciences — Erzurum
Identifiers
NCT: NCT07530185 · UcarPhD2026