Healthy VolunteersNCT07090421
Caffeine Dose: Performance and Recovery
A study testing Cellulose Powder, Caffeine 3 mg/kg Oral Powder and Caffeine 6 mg/kg Oral Powder in people with Healthy Volunteers and Caffeine, run by Ulaç Can YILDIRIM at 1 site in Turkey (Türkiye).
Trial 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. Read more about this study
- Who is it for?
- Ages 20 to 25 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteers, Caffeine, Sleep Quality
- What is being tested?
- Cellulose Powder, Caffeine 3 mg/kg Oral Powder and Caffeine 6 mg/kg Oral Powder
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 13 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 24 Jul 2022to 24 Aug 2022
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 20 to 25 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Sinop University Facility
Sinop, Centarl, 57100
About this study
Official title: Varying Doses of Evening Caffeine Ingestion Have Different Effects on Rowing Ergometer Performance, Sleep Quality and Wakefulness Scores
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.
Read more
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.
Read the detailed description
This double-blind, randomized crossover study examined the dose-dependent effects of evening caffeine ingestion on rowing performance, sleep quality, and daytime alertness in trained male university rowers. The rationale stems from increasing use of caffeine as a performance-enhancing supplement in evening training or competition settings, despite its known adverse effects on sleep and recovery. Thirteen participants completed four experimental trials (placebo, 3 mg/kg, 6 mg/kg, 9 mg/kg caffeine), each separated by a washout period, during which they performed a 2000-meter rowing time trial and were assessed for sleep quality and daytime sleepiness using validated scales. The study also recorded physiological responses and adverse events across conditions. By evaluating multiple doses, the design allowed for assessment of both efficacy and tolerability thresholds, supporting dose-optimization strategies. This study aims to inform practical guidelines for athletes and coaches balancing acute ergogenic benefits with potential recovery trade-offs when caffeine is used late in the day.
- Conditions
- Healthy Volunteers, Caffeine, Sleep Quality
- Being tested
- Cellulose Powder, Caffeine 3 mg/kg Oral Powder, Caffeine 6 mg/kg Oral Powder, Caffeine 9 mg/kg Oral Powder
- Keywords
- Caffeine, Dose-response, Rowing performance, Sleep quality, Wakefulness
- Medical subject headings
- Sleep Initiation and Maintenance Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Cellulose PowderDietary 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.
Caffeine 3 mg/kg Oral PowderDietary 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.
Caffeine 6 mg/kg Oral PowderDietary 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.
Caffeine 9 mg/kg Oral PowderDietary 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.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: 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. Receives: 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. Receives: Dietary Supplement: Caffeine 9 mg/kg Oral Powder |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Morning following each test day (approximately 10-12 hours post-dose)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Jul 2025
- Study start24 Jul 2022
- Primary completion24 Aug 2022
- Study completion24 Aug 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for Healthy VolunteersStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 13 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ulaç Can YILDIRIM
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Ulaç Can YILDIRIM, Sinop University
- Investigators
- Ulas C. Yildirim, pHd, Principal investigator, Sinop University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07090421
- Sponsor's protocol ID
- 2021/80
- Status last verified
- Jul 2025
- First submitted
- 4 Jul 2025
- Last updated
- 29 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data (IPD) underlying the results reported in the publication, including performance outcomes, sleep-related metrics, and adverse event reports, will be made available upon reasonable request to qualified researchers. Data will be de-identified to protect participant confidentiality. The data will become accessible after publication of the main results and will be available for up to five years. A data dictionary will also be provided to facilitate proper interpretation.
Publications
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.
PubMed 25700100Anderson 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.
PubMed 11099373Bonnar 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.
PubMed 29352373Chen 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.
PubMed 38836626de 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.
PubMed 35380245Drapeau 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.
PubMed 16704567
Study at a glance
From the registry record, last updated by the sponsor on 29 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Varying Doses of Evening Caffeine Ingestion Have Different Effects on Rowing Ergometer Performance, Sleep Quality and Wakefulness Scores
- ClinicalTrials.gov ID
- NCT07090421
- Acronym / sponsor ID
- 2021/80
- Conditions
- Healthy Volunteers, Caffeine, Sleep Quality
- Keywords
- Caffeine, Dose-response, Rowing performance, Sleep quality, Wakefulness
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 13 participants (actual)
- Lead sponsor
- Ulaç Can YILDIRIMUniversity, hospital or other
- Study start
- 24 Jul 2022 (actual)
- Primary completion
- 24 Aug 2022 (actual)
- Study completion
- 24 Aug 2022 (actual)
- First posted
- 29 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
This double-blind, randomized crossover study examined the dose-dependent effects of evening caffeine ingestion on rowing performance, sleep quality, and daytime alertness in trained male university rowers. The rationale stems from increasing use of caffeine as a performance-enhancing supplement in evening training or competition settings, despite its known adverse effects on sleep and recovery. Thirteen participants completed four experimental trials (placebo, 3 mg/kg, 6 mg/kg, 9 mg/kg caffeine), each separated by a washout period, during which they performed a 2000-meter rowing time trial and were assessed for sleep quality and daytime sleepiness using validated scales. The study also recorded physiological responses and adverse events across conditions. By evaluating multiple doses, the design allowed for assessment of both efficacy and tolerability thresholds, supporting dose-optimization strategies. This study aims to inform practical guidelines for athletes and coaches balancing acute ergogenic benefits with potential recovery trade-offs when caffeine is used late in the day.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Dietary Supplement: Cellulose PowderParticipants 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. |
| Low Dose Caffeine | Experimental | Dietary Supplement: Caffeine 3 mg/kg Oral PowderParticipants 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. |
| Moderate Dose Caffeine | Experimental | Dietary Supplement: Caffeine 6 mg/kg Oral PowderParticipants 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. |
| High Dose Caffeine | Experimental | Dietary Supplement: Caffeine 9 mg/kg Oral PowderParticipants 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. |
Who may qualify
- Ages
- 20 to 25 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- 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)
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Cellulose PowderParticipants 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. | Dietary supplement | Placebo |
| Caffeine 3 mg/kg Oral PowderParticipants 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. | Dietary supplement | Low Dose Caffeine |
| Caffeine 6 mg/kg Oral PowderParticipants 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. | Dietary supplement | Moderate Dose Caffeine |
| Caffeine 9 mg/kg Oral PowderA 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. | Dietary supplement | High Dose Caffeine |
Primary outcome
Change in 2000-meter Rowing Ergometer Completion Time (seconds) Following Varying Doses of Evening Caffeine Ingestion
Time frame: Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)
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.
Subjective Sleep Quality Score (5-point Likert Scale)
Time frame: Morning following each test day (approximately 10-12 hours post-dose)
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.
Mean Power Output (Watts) During 2000-meter Rowing Ergometer Trial
Time frame: Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)
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.
Daytime Sleepiness Score (Epworth Sleepiness Scale)
Time frame: Morning following each test day (approximately 10-12 hours post-dose)
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.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Jul 2025.
- Background: PubMed 25700100Ali 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.
- Background: PubMed 11099373Anderson 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.
- Background: PubMed 29352373Bonnar 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.
- Background: PubMed 38836626Chen 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.
- Background: PubMed 35380245de 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.
- Background: PubMed 16704567Drapeau 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.
- Individual participant dataSharing planned: Yes. Individual participant data (IPD) underlying the results reported in the publication, including performance outcomes, sleep-related metrics, and adverse event reports, will be made available upon reasonable request to qualified researchers. Data will be de-identified to protect participant confidentiality. The data will become accessible after publication of the main results and will be available for up to five years. A data dictionary will also be provided to facilitate proper interpretation.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Ulas C. Yildirim, pHd principal investigator
Sinop University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Cellulose Powder, Caffeine 3 mg/kg Oral Powder and Caffeine 6 mg/kg Oral Powder in people with Healthy Volunteers and Caffeine, run by Ulaç Can YILDIRIM at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in 2000-meter Rowing Ergometer Completion Time (seconds) Following Varying Doses of Evening Caffeine Ingestion (time frame: Approximately 60 minutes post-ingestion on each test day, during evening sessions (between 6:00 PM and 9:00 PM)). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07090421, which also lists 6 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Jul 2025.