Healthy Adult MaleNCT07596511
Acute Effects of Caffeine on Repeated Sprint Performance and Energy Distribution
A study testing Cycling Repeated Sprint Test (6 × 10 s), Breath-by-Breath VO₂ Monitoring - COSMED K5 and Capillary Blood Lactate Sampling (non-invasive) in people with Healthy Adult Male, run by Trabzon University at 1 site in Turkey (Türkiye).
Trial summary
The goal of this study is to learn if low-dose caffeinated coffee improves repeated sprint performance and affects energy system contributions in combat sports athletes. The main questions it aims to answer are: Does low-dose caffeinated coffee (1.5 or 3 mg·kg-¹) improve peak power, mean power, and fatigue index… Read more about this study
- Who is it for?
- Ages 18 to 25 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Healthy Adult Male
- What is being tested?
- Cycling Repeated Sprint Test (6 × 10 s), Breath-by-Breath VO₂ Monitoring - COSMED K5 and Capillary Blood Lactate Sampling (non-invasive)
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 15 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 15 Apr 2025to 30 May 2025
- 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 18 to 25 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Male combat sports athletes aged 18 to 25 years
- Minimum of five years of continuous structured training
- Competitive experience at both regional (state) and national levels
- Willingness to abstain from all caffeinated products for two weeks prior to and throughout the study period
- Ability to follow a standardized dietary protocol prescribed by an Olympic Preparation Center dietitian
- Provision of written informed consent
Who cannot join
- Age below 18 years
- Self-reported use of anabolic agents, hormonal modulators, or performance-influencing dietary supplements within the three months preceding enrollment
- Current use of narcotic, psychotropic, stimulant medications, or tobacco products during the assessment period
- Presence of any diagnosed medical condition (including cardiovascular, metabolic, neurological, respiratory, or musculoskeletal disorders) that may compromise safe participation
- Withdrawal from the study at the participant's own request
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Trabzon University Faculty of Sport Sciences
Trabzon, Akçaabat, 61300
About this study
Official title: Acute Effect of Caffeinated and Decaffeinated Coffee Consumption on Repeated Sprint Performance and Energy Contribution Distribution
The goal of this study is to learn if low-dose caffeinated coffee improves repeated sprint performance and affects energy system contributions in combat sports athletes.
The main questions it aims to answer are:
- Does low-dose caffeinated coffee (1.5 or 3 mg·kg-¹) improve peak power, mean power, and fatigue index during repeated sprint tests?
- What physiological responses (heart rate, blood lactate, perceived exertion, and energy system contributions) do participants have when consuming caffeinated coffee? Researchers compared caffeinated coffee at two doses (1.5 and 3 mg·kg-¹ body mass) to a placebo (decaffeinated coffee of identical taste and appearance) to see if low
Read the detailed description
This investigation examined whether acute ingestion of low-dose caffeine delivered through commercially available regular coffee would alter repeated sprint capacity and metabolic energy system dynamics in athletes who compete in combat disciplines. A within-subject, double-blind, placebo-controlled crossover framework was adopted to ensure methodological rigor and minimize order and expectation biases. Eligible participants were physically active male combat sports competitors (n = 15; aged 18-25 years) with a documented competitive history spanning at least five years at the regional and national levels. Volunteers were excluded if they reported recent use of performance-modifying agents, stimulant or psychotropic medications, tobacco products, or any diagnosed condition affecting cardiovascular, metabolic, or musculoskeletal function. To standardize caffeine baseline, all participants were instructed to abstain from caffeinated products for a minimum of two weeks prior to the study onset and throughout the entire data collection period.
Each participant attended the laboratory on four separate occasions. The initial visit served as a familiarization session and included anthropometric assessment. The subsequent three sessions were assigned in a randomized, counterbalanced order, with a minimum 48-hour recovery interval separating each visit. During these sessions, participants received one of three coded supplementation conditions - placebo (decaffeinated coffee), low-dose caffeine (1.5 mg·kg-¹ body mass), or moderate-low-dose caffeine (3 mg·kg-¹ body mass) - each dissolved in 250 mL of hot water and consumed over a 10-minute period. The caffeine content of both the caffeinated and decaffeinated coffee products (Nescafe Gold) was verified by an accredited food analysis laboratory. To maintain identical volume, appearance, and taste across all conditions, decaffeinated and caffeinated coffees were blended in varying proportions for each dose level. Supplementation was administered 60 minutes before the commencement of exercise testing. Performance testing comprised a standardized cycling-based repeated sprint protocol: six 10-second maximal effort sprints, each separated by a 30-second passive recovery period, performed on a mechanically braked cycle ergometer (Monark 894E) with resistance set at 10% of individual body mass. A structured warm-up preceded each testing bout. Primary performance variables derived from sprint testing included peak power output, mean power output, and fatigue index. Perceptual and physiological responses were documented via the Borg rating of perceived exertion scale, peak heart rate, and capillary blood lactate concentration measured at rest and immediately following the final sprint. Breath-by-breath oxygen uptake data were collected continuously using a portable metabolic system (COSMED K5) to facilitate estimation of energy system contributions. The relative and absolute contributions of the phosphocreatine (ATP-PCr), glycolytic, and oxidative metabolic pathways were quantified using established indirect methods. Excess post-exercise oxygen consumption (EPOC) kinetics were modeled with mono-exponential curve fitting to isolate the fast EPOC component, which served as a proxy for PCr resynthesis. Glycolytic contribution was estimated from the net change in blood lactate concentration, applying an established oxygen-equivalent conversion factor. Oxidative metabolism was derived from the net elevation in VO₂ above resting values during exercise. Total energy expenditure was computed as the cumulative sum of all three pathway contributions. To control for dietary and diurnal confounders, participants replicated identical pre-test meal patterns documented during the first testing session, and all laboratory visits were conducted between 08:00 and 11:00 h. Dietary adherence was verified through structured diet logs reviewed by the research team. Data were analyzed using one-way repeated-measures ANOVA with Bonferroni-adjusted pairwise comparisons, and partial eta squared (η²p) was reported as the measure of effect magnitude. The study received full ethical clearance from the Trabzon Eurasia University Ethics Committee and was conducted in accordance with the principles outlined in the Declaration of Helsinki. Informed consent form obtained from all the participants.
- Conditions
- Healthy Adult Male
- Being tested
- Cycling Repeated Sprint Test (6 × 10 s), Breath-by-Breath VO₂ Monitoring - COSMED K5, Capillary Blood Lactate Sampling (non-invasive), Heart Rate Monitoring
- Keywords
- basic science
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Cycling Repeated Sprint Test (6 × 10 s)Other
A standardized cycling-based repeated sprint protocol consisting of six 10-second maximal-effort sprints, each separated by a 30-second passive rest interval, performed on a mechanically braked cycle ergometer (Monark 894E, Vansbro, Sweden). Resistance was calibrated at 10% of the participant's individual body mass. The inertial momentum of the flywheel was excluded from power output calculations following the approach described by Bogdanis et al. (2008). Each session was preceded by a structured warm-up consisting of five 30-second bouts at 100 W, followed by a 5-minute seated rest before test commencement. Each participant initiated the protocol with their dominant leg to ensure procedural consistency across all sessions.
Breath-by-Breath VO₂ Monitoring - COSMED K5Other
Continuous breath-by-breath oxygen uptake (VO₂) data were collected throughout each testing session using the COSMED K5 portable metabolic system (Rome, Italy). Data were used to estimate the relative and absolute contributions of the three metabolic energy pathways. The fast component of excess post-exercise oxygen consumption (EPOC) was extracted and modeled using a mono-exponential function (OriginPro 8.0, OriginLab Corp.) to estimate phosphocreatine (PCr) resynthesis during recovery intervals and following the final sprint. Oxidative metabolism contribution was derived by subtracting resting VO₂ from exercise VO₂. Total energy demand was expressed in both liters of O₂ and kilojoules (caloric equivalent: 20.92 kJ·L-¹ O₂).
Capillary Blood Lactate Sampling (non-invasive)Other
Capillary blood samples were obtained at two time points per session: (1) resting lactate (LA_rest) - collected following a 20-minute passive rest period immediately before the sprint test, in accordance with published lactate clearance protocols; and (2) maximal post-exercise lactate (LA_max) - collected immediately upon completion of the final sprint repetition. Delta lactate (ΔLA) was calculated as the arithmetic difference between LA_max and LA_rest and expressed in mmol·L-¹. Delta lactate values were additionally used to estimate the glycolytic energy system contribution, applying a conversion factor of 3 mL O₂·kg-¹ body mass per 1 mmol·L-¹ increase in blood lactate concentration (Di Prampero \& Ferretti, 1999).
Heart Rate MonitoringOther
Continuous heart rate was recorded throughout each testing session via chest type radiotelemetry sensor integrated with COSMED K5. Peak heart rate (HR_peak, bpm) was defined as the highest value observed across the entire repeated sprint protocol and reported as a secondary physiological outcome.
| Study group | Role | What they receive |
|---|---|---|
| Placebo | Placebo comparator | Participants ingested decaffeinated coffee (Nescafe Gold, decaffeinated) at a dose equivalent to 3 mg·kg-¹ of body mass, dissolved in 250 mL of hot water and consumed over 10 minutes, administered 60 minutes before the exercise test. Receives: Other: Cycling Repeated Sprint Test (6 × 10 s); Other: Breath-by-Breath VO₂ Monitoring - COSMED K5; Other: Capillary Blood Lactate Sampling (non-invasive); Other: Heart Rate Monitoring |
| Low-Dose Caffeine - 1.5 mg·kg-¹ | Experimental | A blended preparation of caffeinated and decaffeinated (for the similar taste of intensity with 3 mg/kg intervention) Nescafe Gold coffee dissolved in 250 ml hot water was administered at a total dose corresponding to 1.5 mg·kg-¹ body mass of caffeine. Volume was equalized to the placebo condition through addition of decaffeinated coffee. Receives: Other: Cycling Repeated Sprint Test (6 × 10 s); Other: Breath-by-Breath VO₂ Monitoring - COSMED K5; Other: Capillary Blood Lactate Sampling (non-invasive); Other: Heart Rate Monitoring |
| Low-Dose Caffeine - 3 mg·kg-¹ | Experimental | Regular caffeinated Nescafe Gold coffee dissolved in 250 ml hot water was administered at a dose delivering 3 mg·kg-¹ body mass of caffeine. Receives: Other: Cycling Repeated Sprint Test (6 × 10 s); Other: Breath-by-Breath VO₂ Monitoring - COSMED K5; Other: Capillary Blood Lactate Sampling (non-invasive); Other: Heart Rate Monitoring |
What is being measured
The primary outcome is the main question the study is designed to answer.
Peak Power Output
Highest instantaneous power output (Watts) recorded across all six 10-second sprint bouts on the cycle ergometer (Monark 894E), with resistance set at 10% of body mass.
Measured: On 3 testing days with 48-hour interval
Mean Power Output
Average power output (Watts) calculated across all six sprint efforts, reflecting the athlete's overall capacity to sustain high-intensity output across the full protocol.
Measured: On 3 testing days with 48-hour interval
Fatigue Index
Quantified as: FI = 100 × (1 - total peak power / ideal peak power), where ideal peak power is the product of the highest single-sprint peak power and the total number of repetitions. Expressed as a percentage (%).
Measured: On 3 testing days with 48-hour interval
Secondary outcomes (7)
Total Energy Expenditure
Computed as the cumulative sum of ATP-PCr, glycolytic, and oxidative pathway contributions, expressed in kilojoules (kJ), using a caloric equivalent of 20.92 kJ per liter of O₂ consumed.
Measured: On 3 testing days with 48-hour interval
Energy System - Oxidative Contribution
Estimated absolute contributions (kJ) of each metabolic pathway. Oxidative contribution calculated as net VO₂ elevation above resting baseline. Breath-by-breath VO₂ data collected continuously via COSMED K5 portable metabolic system.
Measured: On 3 testing days with 48-hour interval
Energy System - ATP Contribution
ATP-PCr contribution derived from the fast component of EPOC kinetics modeled via mono-exponential curve fitting (OriginPro 8.0).
Measured: On 3 testing days with 48-hour interval
Energy System - Glycolytic Contribution
Glycolytic contribution estimated from net blood lactate rise (3 mL O₂·kg-¹ per 1 mmol·L-¹ increase).
Measured: On 3 testing days with 48-hour interval
Peak Heart Rate
Highest recorded heart rate (bpm) during the repeated sprint test.
Measured: On 3 testing days with 48-hour interval
Delta Blood Lactate Concentration
Difference between resting capillary blood lactate (measured after 20-minute passive rest prior to testing) and maximum post-exercise lactate (measured immediately following the final sprint). Expressed in mmol·L-¹.
Measured: On 3 testing days with 48-hour interval
Rating of Perceived Exertion
Subjective effort rating collected using the Borg scale (6-20) following the completion of the repeated sprint protocol.
Measured: On 3 testing days with 48-hour interval
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 May 2026
- Study start15 Apr 2025
- Primary completion30 May 2025
- Study completion30 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy Adult MaleStudies 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
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- Trabzon University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Abdulkadir Birol, Trabzon University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07596511
- Sponsor's protocol ID
- E-69268593-050.04-25025
- Status last verified
- May 2026
- First submitted
- 12 May 2026
- Last updated
- 19 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: All the data collected in this study anonymized and only will be used in the scope of academic paper publication.
Study at a glance
From the registry record, last updated by the sponsor on 19 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Acute Effect of Caffeinated and Decaffeinated Coffee Consumption on Repeated Sprint Performance and Energy Contribution Distribution
- ClinicalTrials.gov ID
- NCT07596511
- Acronym / sponsor ID
- E-69268593-050.04-25025
- Conditions
- Healthy Adult Male
- Keywords
- basic science
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 15 participants (actual)
- Lead sponsor
- Trabzon UniversityUniversity, hospital or other
- Study start
- 15 Apr 2025 (actual)
- Primary completion
- 30 May 2025 (actual)
- Study completion
- 30 May 2025 (actual)
- First posted
- 19 May 2026 (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 study is to learn if low-dose caffeinated coffee improves repeated sprint performance and affects energy system contributions in combat sports athletes.
The main questions it aims to answer are:
- Does low-dose caffeinated coffee (1.5 or 3 mg·kg-¹) improve peak power, mean power, and fatigue index during repeated sprint tests?
- What physiological responses (heart rate, blood lactate, perceived exertion, and energy system contributions) do participants have when consuming caffeinated coffee? Researchers compared caffeinated coffee at two doses (1.5 and 3 mg·kg-¹ body mass) to a placebo (decaffeinated coffee of identical taste and appearance) to see if low
Detailed description
This investigation examined whether acute ingestion of low-dose caffeine delivered through commercially available regular coffee would alter repeated sprint capacity and metabolic energy system dynamics in athletes who compete in combat disciplines. A within-subject, double-blind, placebo-controlled crossover framework was adopted to ensure methodological rigor and minimize order and expectation biases. Eligible participants were physically active male combat sports competitors (n = 15; aged 18-25 years) with a documented competitive history spanning at least five years at the regional and national levels. Volunteers were excluded if they reported recent use of performance-modifying agents, stimulant or psychotropic medications, tobacco products, or any diagnosed condition affecting cardiovascular, metabolic, or musculoskeletal function. To standardize caffeine baseline, all participants were instructed to abstain from caffeinated products for a minimum of two weeks prior to the study onset and throughout the entire data collection period.
Each participant attended the laboratory on four separate occasions. The initial visit served as a familiarization session and included anthropometric assessment. The subsequent three sessions were assigned in a randomized, counterbalanced order, with a minimum 48-hour recovery interval separating each visit. During these sessions, participants received one of three coded supplementation conditions - placebo (decaffeinated coffee), low-dose caffeine (1.5 mg·kg-¹ body mass), or moderate-low-dose caffeine (3 mg·kg-¹ body mass) - each dissolved in 250 mL of hot water and consumed over a 10-minute period. The caffeine content of both the caffeinated and decaffeinated coffee products (Nescafe Gold) was verified by an accredited food analysis laboratory. To maintain identical volume, appearance, and taste across all conditions, decaffeinated and caffeinated coffees were blended in varying proportions for each dose level. Supplementation was administered 60 minutes before the commencement of exercise testing. Performance testing comprised a standardized cycling-based repeated sprint protocol: six 10-second maximal effort sprints, each separated by a 30-second passive recovery period, performed on a mechanically braked cycle ergometer (Monark 894E) with resistance set at 10% of individual body mass. A structured warm-up preceded each testing bout. Primary performance variables derived from sprint testing included peak power output, mean power output, and fatigue index. Perceptual and physiological responses were documented via the Borg rating of perceived exertion scale, peak heart rate, and capillary blood lactate concentration measured at rest and immediately following the final sprint. Breath-by-breath oxygen uptake data were collected continuously using a portable metabolic system (COSMED K5) to facilitate estimation of energy system contributions. The relative and absolute contributions of the phosphocreatine (ATP-PCr), glycolytic, and oxidative metabolic pathways were quantified using established indirect methods. Excess post-exercise oxygen consumption (EPOC) kinetics were modeled with mono-exponential curve fitting to isolate the fast EPOC component, which served as a proxy for PCr resynthesis. Glycolytic contribution was estimated from the net change in blood lactate concentration, applying an established oxygen-equivalent conversion factor. Oxidative metabolism was derived from the net elevation in VO₂ above resting values during exercise. Total energy expenditure was computed as the cumulative sum of all three pathway contributions. To control for dietary and diurnal confounders, participants replicated identical pre-test meal patterns documented during the first testing session, and all laboratory visits were conducted between 08:00 and 11:00 h. Dietary adherence was verified through structured diet logs reviewed by the research team. Data were analyzed using one-way repeated-measures ANOVA with Bonferroni-adjusted pairwise comparisons, and partial eta squared (η²p) was reported as the measure of effect magnitude. The study received full ethical clearance from the Trabzon Eurasia University Ethics Committee and was conducted in accordance with the principles outlined in the Declaration of Helsinki. Informed consent form obtained from all the participants.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Other: Cycling Repeated Sprint Test (6 × 10 s), Other: Breath-by-Breath VO₂ Monitoring - COSMED K5, Other: Capillary Blood Lactate Sampling (non-invasive), Other: Heart Rate MonitoringParticipants ingested decaffeinated coffee (Nescafe Gold, decaffeinated) at a dose equivalent to 3 mg·kg-¹ of body mass, dissolved in 250 mL of hot water and consumed over 10 minutes, administered 60 minutes before the exercise test. |
| Low-Dose Caffeine - 1.5 mg·kg-¹ | Experimental | Other: Cycling Repeated Sprint Test (6 × 10 s), Other: Breath-by-Breath VO₂ Monitoring - COSMED K5, Other: Capillary Blood Lactate Sampling (non-invasive), Other: Heart Rate MonitoringA blended preparation of caffeinated and decaffeinated (for the similar taste of intensity with 3 mg/kg intervention) Nescafe Gold coffee dissolved in 250 ml hot water was administered at a total dose corresponding to 1.5 mg·kg-¹ body mass of caffeine. Volume was equalized to the placebo condition through addition of decaffeinated coffee. |
| Low-Dose Caffeine - 3 mg·kg-¹ | Experimental | Other: Cycling Repeated Sprint Test (6 × 10 s), Other: Breath-by-Breath VO₂ Monitoring - COSMED K5, Other: Capillary Blood Lactate Sampling (non-invasive), Other: Heart Rate MonitoringRegular caffeinated Nescafe Gold coffee dissolved in 250 ml hot water was administered at a dose delivering 3 mg·kg-¹ body mass of caffeine. |
Who may qualify
- Ages
- 18 to 25 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Male combat sports athletes aged 18 to 25 years
- Minimum of five years of continuous structured training
- Competitive experience at both regional (state) and national levels
- Willingness to abstain from all caffeinated products for two weeks prior to and throughout the study period
- Ability to follow a standardized dietary protocol prescribed by an Olympic Preparation Center dietitian
Key exclusion criteria (5 listed)
- Age below 18 years
- Self-reported use of anabolic agents, hormonal modulators, or performance-influencing dietary supplements within the three months preceding enrollment
- Current use of narcotic, psychotropic, stimulant medications, or tobacco products during the assessment period
- Presence of any diagnosed medical condition (including cardiovascular, metabolic, neurological, respiratory, or musculoskeletal disorders) that may compromise safe participation
- Withdrawal from the study at the participant's own request
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 |
|---|---|---|
| Cycling Repeated Sprint Test (6 × 10 s)A standardized cycling-based repeated sprint protocol consisting of six 10-second maximal-effort sprints, each separated by a 30-second passive rest interval, performed on a mechanically braked cycle ergometer (Monark 894E, Vansbro, Sweden). Resistance was calibrated at 10% of the participant's individual body mass. The inertial momentum of the flywheel was excluded from power output calculations following the approach described by Bogdanis et al. (2008). Each session was preceded by a structured warm-up consisting of five 30-second bouts at 100 W, followed by a 5-minute seated rest before test commencement. Each participant initiated the protocol with their dominant leg to ensure procedural consistency across all sessions. | Other | Low-Dose Caffeine - 1.5 mg·kg-¹, Low-Dose Caffeine - 3 mg·kg-¹, Placebo |
| Breath-by-Breath VO₂ Monitoring - COSMED K5Continuous breath-by-breath oxygen uptake (VO₂) data were collected throughout each testing session using the COSMED K5 portable metabolic system (Rome, Italy). Data were used to estimate the relative and absolute contributions of the three metabolic energy pathways. The fast component of excess post-exercise oxygen consumption (EPOC) was extracted and modeled using a mono-exponential function (OriginPro 8.0, OriginLab Corp.) to estimate phosphocreatine (PCr) resynthesis during recovery intervals and following the final sprint. Oxidative metabolism contribution was derived by subtracting resting VO₂ from exercise VO₂. Total energy demand was expressed in both liters of O₂ and kilojoules (caloric equivalent: 20.92 kJ·L-¹ O₂). | Other | Low-Dose Caffeine - 1.5 mg·kg-¹, Low-Dose Caffeine - 3 mg·kg-¹, Placebo |
| Capillary Blood Lactate Sampling (non-invasive)Capillary blood samples were obtained at two time points per session: (1) resting lactate (LA_rest) - collected following a 20-minute passive rest period immediately before the sprint test, in accordance with published lactate clearance protocols; and (2) maximal post-exercise lactate (LA_max) - collected immediately upon completion of the final sprint repetition. Delta lactate (ΔLA) was calculated as the arithmetic difference between LA_max and LA_rest and expressed in mmol·L-¹. Delta lactate values were additionally used to estimate the glycolytic energy system contribution, applying a conversion factor of 3 mL O₂·kg-¹ body mass per 1 mmol·L-¹ increase in blood lactate concentration (Di Prampero \& Ferretti, 1999). | Other | Low-Dose Caffeine - 1.5 mg·kg-¹, Low-Dose Caffeine - 3 mg·kg-¹, Placebo |
| Heart Rate MonitoringContinuous heart rate was recorded throughout each testing session via chest type radiotelemetry sensor integrated with COSMED K5. Peak heart rate (HR_peak, bpm) was defined as the highest value observed across the entire repeated sprint protocol and reported as a secondary physiological outcome. | Other | Low-Dose Caffeine - 1.5 mg·kg-¹, Low-Dose Caffeine - 3 mg·kg-¹, Placebo |
Primary outcome
Peak Power Output
Time frame: On 3 testing days with 48-hour interval
Highest instantaneous power output (Watts) recorded across all six 10-second sprint bouts on the cycle ergometer (Monark 894E), with resistance set at 10% of body mass.
Mean Power Output
Time frame: On 3 testing days with 48-hour interval
Average power output (Watts) calculated across all six sprint efforts, reflecting the athlete's overall capacity to sustain high-intensity output across the full protocol.
Fatigue Index
Time frame: On 3 testing days with 48-hour interval
Quantified as: FI = 100 × (1 - total peak power / ideal peak power), where ideal peak power is the product of the highest single-sprint peak power and the total number of repetitions. Expressed as a percentage (%).
7 secondary outcomes
Total Energy Expenditure
Time frame: On 3 testing days with 48-hour interval
Energy System - Oxidative Contribution
Time frame: On 3 testing days with 48-hour interval
Energy System - ATP Contribution
Time frame: On 3 testing days with 48-hour interval
Energy System - Glycolytic Contribution
Time frame: On 3 testing days with 48-hour interval
Peak Heart Rate
Time frame: On 3 testing days with 48-hour interval
Delta Blood Lactate Concentration
Time frame: On 3 testing days with 48-hour interval
Rating of Perceived Exertion
Time frame: On 3 testing days with 48-hour interval
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 19 May 2026.
- Individual participant dataSharing planned: No. All the data collected in this study anonymized and only will be used in the scope of academic paper publication.
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Cycling Repeated Sprint Test (6 × 10 s), Breath-by-Breath VO₂ Monitoring - COSMED K5 and Capillary Blood Lactate Sampling (non-invasive) in people with Healthy Adult Male, run by Trabzon University 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 6 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 19 May 2026. 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?
Peak Power Output (time frame: On 3 testing days with 48-hour interval). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 19 May 2026.