Caffeine Dose: Performance and Recovery

NCT07090421 | Completed

• 1 other identifier: 2021/80
• Study Type: interventional
• Target: 13
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn how different doses of caffeine taken in the evening affect rowing performance, sleep quality, and daytime alertness in trained male university rowers. The main questions it aims to answer are: Does a low, moderate, or high caffeine dose improve rowing performance? How do these doses affect sleep and recovery after evening exercise? Participants completed four rowing tests after consuming either a placebo, low (3 mg/kg), moderate (6 mg/kg), or high (9 mg/kg) dose of caffeine. Researchers measured rowing time, power, heart rate, sleep quality, and daytime sleepiness. The study found that moderate and high caffeine doses improved rowing performance the most. However, these same doses made it harder for participants to sleep well and feel alert the next day. Headaches and stomach issues were also more common with the high dose. The low dose gave smaller performance gains but caused fewer side effects. This study shows that evening caffeine can boost performance but may hurt recovery and sleep. Athletes and coaches should weigh these trade-offs when using caffeine for late-day training or competition.

Conditions

Healthy Volunteers; Caffeine; Sleep Quality

Keywords

Caffeine; Dose-response; Rowing performance; Sleep quality; Wakefulness

Outcome Measures

Primary Outcomes (4)

• Change in 2000-meter Rowing Ergometer Completion Time (seconds) Following Varying Doses of Evening Caffeine Ingestion

  The time in seconds required to complete a 2000-meter rowing ergometer trial was recorded under four separate conditions: placebo, and caffeine doses of 3 mg/kg, 6 mg/kg, and 9 mg/kg. Each participant completed one trial per condition in a randomized, double-blind, crossover design. Performance was measured using a Concept2 rowing ergometer with integrated time-tracking software. Trials were conducted in the evening (between 6:00 PM and 9:00 PM), approximately 60 minutes after ingestion of the assigned supplement. A lower time indicates better performance.

  Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)

• Subjective Sleep Quality Score (5-point Likert Scale)

  Participants rated their perceived sleep quality the morning after each trial using a 5-point Likert scale (1 = very poor, 5 = very good). Scores reflect subjective assessment of sleep quality following evening caffeine ingestion.

  Morning following each test day (approximately 10-12 hours post-dose)

• Mean Power Output (Watts) During 2000-meter Rowing Ergometer Trial

  Average power output (in watts) generated by participants during each 2000-meter rowing trial. Power was recorded via Concept2 ergometer's internal performance monitor, calculated over the full distance. A higher value indicates better performance.

  Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)

• Daytime Sleepiness Score (Epworth Sleepiness Scale)

  Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS), a validated questionnaire consisting of 8 items, each scored from 0 to 3. Total scores range from 0 (no sleepiness) to 24 (severe sleepiness). Higher scores indicate more sleepiness.

  Morning following each test day (approximately 10-12 hours post-dose)

Study Arms (4)

Placebo

PLACEBO COMPARATOR

Participants ingested an inert cellulose capsule containing no active substance approximately 60 minutes prior to performing a 2000-meter rowing ergometer time trial. This condition served as the control to compare the effects of caffeine ingestion at varying doses.

Dietary Supplement: Cellulose Powder

Low Dose Caffeine

EXPERIMENTAL

Participants ingested a caffeine capsule at a dosage of 3 mg per kg of body mass approximately 60 minutes before the 2000-meter rowing ergometer trial. This condition was included to evaluate the ergogenic and sleep-related effects of a low evening caffeine dose.

Dietary Supplement: Caffeine 3 mg/kg Oral Powder

Moderate Dose Caffeine

EXPERIMENTAL

Participants ingested a caffeine capsule at a dosage of 6 mg per kg of body mass approximately 60 minutes before performing the 2000-meter rowing ergometer test. This condition represented a commonly used moderate dose to examine its impact on performance and sleep parameters.

Dietary Supplement: Caffeine 6 mg/kg Oral Powder

High Dose Caffeine

EXPERIMENTAL

Participants ingested a caffeine capsule at a dosage of 9 mg per kg of body mass approximately 60 minutes prior to the rowing trial. This high-dose condition was used to assess the maximum ergogenic potential of caffeine and its possible detrimental effects on sleep quality and next-day recovery.

Dietary Supplement: Caffeine 9 mg/kg Oral Powder

Interventions

Cellulose Powder DIETARY_SUPPLEMENT

Participants consumed an inert cellulose powder dissolved in water, containing no active caffeine. The placebo was ingested orally 60 minutes prior to the rowing performance test. This condition served as the control and was administered once per session in a randomized, double-blind, crossover design.

Placebo

Caffeine 3 mg/kg Oral Powder DIETARY_SUPPLEMENT

Participants consumed caffeine in powder form at a dose of 3 milligrams per kilogram of body weight. The powder was dissolved in water and ingested orally approximately 60 minutes before the start of the 2000-meter rowing ergometer performance test. The intervention was administered once per session in a randomized, double-blind, crossover design.

Low Dose Caffeine

Caffeine 6 mg/kg Oral Powder DIETARY_SUPPLEMENT

Participants ingested caffeine in powder form, dissolved in water, at a dose of 6 milligrams per kilogram of body mass. The solution was consumed orally 60 minutes prior to the 2000-meter rowing performance test. This intervention was administered once per session as part of a randomized, double-blind, crossover design.

Moderate Dose Caffeine

Caffeine 9 mg/kg Oral Powder DIETARY_SUPPLEMENT

A powdered caffeine dose of 9 milligrams per kilogram was dissolved in water and consumed orally by participants 60 minutes before a 2000-meter rowing ergometer trial. The intervention was administered once per session under a randomized, double-blind, crossover design.

High Dose Caffeine

Eligibility Criteria

• Age: 20 Years - 25 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Male university-level rowers
• Aged approximately 22 ± 2.2 years
• Minimum of 2 years of rowing training experience
• Free of any medical condition that impairs exercise participation
• Regular caffeine consumers (habitual daily intake recorded)
• Voluntarily signed informed consent form
• Available to attend all scheduled laboratory sessions

You may not qualify if:

• Any medical condition that could interfere with study participation or protocol adherence
• Use of prescription medications during the study period
• Known allergy to mannitol or other artificial sweeteners
• Diagnosed sleep disorders (e.g., insomnia, sleep apnea)
• Physician's advice to limit or avoid caffeine intake

Sponsors & Collaborators

• Ulaç Can YILDIRIM: lead

Study Sites (1)

Sinop University Facility

Sinop, Centarl, 57100, Turkey (Türkiye)

Location

Related Publications (6)

• Ali A, O'Donnell JM, Starck C, Rutherfurd-Markwick KJ. The Effect of Caffeine Ingestion during Evening Exercise on Subsequent Sleep Quality in Females. Int J Sports Med. 2015 Jun;36(6):433-9. doi: 10.1055/s-0034-1398580. Epub 2015 Feb 20.

  PMID: 25700100 BACKGROUND

• Anderson ME, Bruce CR, Fraser SF, Stepto NK, Klein R, Hopkins WG, Hawley JA. Improved 2000-meter rowing performance in competitive oarswomen after caffeine ingestion. Int J Sport Nutr Exerc Metab. 2000 Dec;10(4):464-75. doi: 10.1123/ijsnem.10.4.464.

  PMID: 11099373 BACKGROUND

• Bonnar D, Bartel K, Kakoschke N, Lang C. Sleep Interventions Designed to Improve Athletic Performance and Recovery: A Systematic Review of Current Approaches. Sports Med. 2018 Mar;48(3):683-703. doi: 10.1007/s40279-017-0832-x.

  PMID: 29352373 BACKGROUND

• Chen B, Ding L, Qin Q, Lei TH, Girard O, Cao Y. Effect of caffeine ingestion on time trial performance in cyclists: a systematic review and meta-analysis. J Int Soc Sports Nutr. 2024 Dec;21(1):2363789. doi: 10.1080/15502783.2024.2363789. Epub 2024 Jun 5.

  PMID: 38836626 BACKGROUND

• de Souza JG, Del Coso J, Fonseca FS, Silva BVC, de Souza DB, da Silva Gianoni RL, Filip-Stachnik A, Serrao JC, Claudino JG. Risk or benefit? Side effects of caffeine supplementation in sport: a systematic review. Eur J Nutr. 2022 Dec;61(8):3823-3834. doi: 10.1007/s00394-022-02874-3. Epub 2022 Apr 5.

  PMID: 35380245 BACKGROUND

• Drapeau C, Hamel-Hebert I, Robillard R, Selmaoui B, Filipini D, Carrier J. Challenging sleep in aging: the effects of 200 mg of caffeine during the evening in young and middle-aged moderate caffeine consumers. J Sleep Res. 2006 Jun;15(2):133-41. doi: 10.1111/j.1365-2869.2006.00518.x.

  PMID: 16704567 BACKGROUND

MeSH Terms

Conditions

Sleep Initiation and Maintenance Disorders

Interventions

Caffeine; Powders

Condition Hierarchy (Ancestors)

Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases; Mental Disorders

Intervention Hierarchy (Ancestors)

Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Dosage Forms; Pharmaceutical Preparations

Study Officials

• Ulas C. Yildirim, pHd

  Sinop University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Assoc. Prof.

Study Record Dates

• First Submitted: July 4, 2025
• First Posted: July 29, 2025
• Study Start: July 24, 2022
• Primary Completion: August 24, 2022
• Study Completion: August 24, 2022
• Last Updated: July 29, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Individual participant data (IPD) will be available beginning 6 months after publication of the study results and will be accessible for up to 5 years.
• Access Criteria: Qualified researchers who provide a methodologically sound proposal will be granted access to the deidentified individual participant data. Proposals should be submitted to \[your email address or institutional contact\]. Access will be granted for research purposes only and in accordance with data use agreements.

Locations

TU (1)