Effects of L-Tyrosine and Caffeine on Performance in Elite Boxers

NCT07530185 | Not Yet Recruiting

• 1 other identifier: UcarPhD2026
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

Participants will complete five sessions, including one familiarization and baseline session and four experimental conditions (placebo, L-tyrosine, caffeine, and combined supplementation). The baseline session will include resting measurements. The experimental conditions will be performed in a randomized, counterbalanced crossover design with a washout period of at least 72 hours between sessions.

Conditions

Sports Performance

Keywords

L-tyrosine; Caffeine; Boxing; BDNF; Cognitive performance; Anaerobic performance

Outcome Measures

Primary Outcomes (1)

• Stroop Test Performance

  Cognitive performance assessed using the Stroop test, including reaction time and accuracy.

  up to 12 weeks

Secondary Outcomes (2)

• BDNF Levels

  up to 12 weeks

• Oxidative Stress Markers

  up to 12 weeks

Study Arms (4)

Placebo

PLACEBO COMPARATOR

Participants receive placebo condition.

Dietary Supplement: Placebo

L-tyrosine

EXPERIMENTAL

Participants receive L-tyrosine condition.

Dietary Supplement: L-Tyrosine

Caffeine

EXPERIMENTAL

Participants receive caffeine condition.

Dietary Supplement: Caffeine

Combined

EXPERIMENTAL

Participants receive combined supplementation condition.

Dietary Supplement: L-tyrosine + Caffeine

Interventions

Placebo DIETARY_SUPPLEMENT

Placebo solution matched in taste and volume to active supplements.

Placebo

L-Tyrosine DIETARY_SUPPLEMENT

L-tyrosine at 150 mg/kg body weight administered 60 minutes before exercise.

L-tyrosine

Caffeine DIETARY_SUPPLEMENT

Caffeine at 5 mg/kg body weight administered 60 minutes before exercise.

Caffeine

L-tyrosine + Caffeine DIETARY_SUPPLEMENT

Combined L-tyrosine (150 mg/kg) and caffeine (5 mg/kg) administered 60 minutes before exercise.

Combined

Eligibility Criteria

• Age: 18 Years+
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Inonu University: lead
• Ataturk University: collaborator

Study Sites (1)

Ataturk University Faculty of Sport Sciences

Erzurum, Turkey (Türkiye)

Location

MeSH Terms

Interventions

Tyrosine; Caffeine

Intervention Hierarchy (Ancestors)

Amino Acids, Aromatic; Amino Acids, Cyclic; Amino Acids; Amino Acids, Peptides, and Proteins; Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring

Central Study Contacts

Halil UÇAR

CONTACT

+90 5462921133; halil.ucar@inonu.edu.tr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: Both participants and investigators are blinded to the supplementation conditions. Supplements are prepared and coded by an independent researcher to ensure double-blind conditions.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research Assistant and PhD Student

Model Details: Participants will complete four experimental conditions (placebo, L-tyrosine, caffeine, and combined supplementation) in a randomized, counterbalanced crossover design with a washout period of at least 72 hours between sessions.

Study Record Dates

• First Submitted: April 1, 2026
• First Posted: April 15, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): March 1, 2027
• Last Updated: April 15, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)