CYP1A2 PolymorphismNCT06610110
Caffeine, CYPA12 and Resistance Exercise
A study testing Caffeine in people with CYP1A2 Polymorphism and Caffeine and Resistance Exercise, run by Alberto Pérez-López at 2 sites in Spain.
Trial summary
Introduction: Several studies have evaluated and confirmed the ergogenic effect of acute caffeine intake on sports performance, specifically on strength and power performance. However, it remains to be elucidated how CYP1A2 polymorphism influences the acute effects of caffeine on this type of exercise. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- CYP1A2 Polymorphism, Caffeine and Resistance Exercise
- What is being tested?
- Caffeine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 60 participants
- Where
- 2 sitesSpain
- Study dates
- 1 Apr 2024to 30 Jul 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 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age between ≥ 18 and ≤ 35 years.
- Body mass index (BMI) lower than 25 kg/m².
- Physically active subjects (≥150 min/week of moderate exercise).
- Healthy men and women without neurological, cardiometabolic, immunological, or physical conditions that prevent them from performing physical exercise.
- Participants capable of performing the tests.
Who cannot join
- History of neuromuscular, cardiac, or diseases that could affect liver or muscle metabolism.
- Use of drugs or other stimulants that interfere with caffeine intake and intestinal absorption during the tests and study.
- Body mass index (BMI) ≥ 25 kg/m².
- Having undergone prolonged periods of forced physical inactivity during the 6 months prior to the study.
- Performing strenuous exercise within 48 hours prior to the tests.
- Failing to replicate the same food intake on the two experimental days.
- Consuming caffeine after 6 PM on the day prior to training or testing.
Trial locations and contacts
2 sites in 1 country.
Spain2 sites
Facultad de Medicina y Ciencias de la Salud. Universidad de Alcalá
Alcalá de Henares, Madrid, 28805
Facultad de Medicina y Ciencias de la Salud. Universidad de Alcalá
Alcalá de Henares, Madrid
About this study
Official title: Influence of CYP1A2 on the Acute Effect of Caffeine Intake on Resistance Exercise
Introduction: Several studies have evaluated and confirmed the ergogenic effect of acute caffeine intake on sports performance, specifically on strength and power performance. However, it remains to be elucidated how CYP1A2 polymorphism influences the acute effects of caffeine on this type of exercise.
Objectives: The present study aims to analyze the effects of acute caffeine intake on muscular strength, power, and endurance performance according to CYP1A2 polymorphism in men and women.
- Being tested
- Caffeine, Placebo
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CaffeineDietary supplement
Acute caffeine intake (3 mg/kg)
PlaceboDietary supplement
Placebo (3 mg/kg maltodextrin)
| Study group | Role | What they receive |
|---|---|---|
| Genotype AA - Male - Caffeine | Experimental | Not described Receives: Dietary Supplement: Caffeine |
| Genotype AC or CC - Male - Caffeine | Experimental | Not described Receives: Dietary Supplement: Caffeine |
| Genotype AA - Male - Placebo | Placebo comparator | Not described Receives: Dietary Supplement: Placebo |
| Genotype AC or CC - Male - Placebo | Placebo comparator | Not described Receives: Dietary Supplement: Placebo |
| Genotype AA - Female - Caffeine | Experimental | Not described Receives: Dietary Supplement: Caffeine |
| Genotype AC or CC - Female - Caffeine | Experimental | Not described Receives: Dietary Supplement: Caffeine |
| Genotype AA - Female - Placebo | Placebo comparator | Not described Receives: Dietary Supplement: Placebo |
| Genotype AC or CC - Female - Placebo | Placebo comparator | Not described Receives: Dietary Supplement: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
cyp1a2 polymorphism
Using saliva sample and PCR
Measured: Before the beginning of the trial
Mean velocity at different %1RM
Measuring bar mean velocity desplacement during bench press and back squat exercises.
Measured: Through study completion, an average of 2 weeks
Peak velocity at different %1RM
Measuring bar peak velocity and time to reach peak velocity of bar desplacement during bench press and back squat exercises.
Measured: Through study completion, an average of 2 weeks
Mean power output at different %1RM
Measuring during bench press and back squat exercises.
Measured: Through study completion, an average of 2 weeks
Peak power output and time to reach peak power output at different %1RM
Measuring during bench press and back squat exercises.
Measured: Through study completion, an average of 2 weeks
Number of repetitions performed in 1 set at 65%1RM until task failure
In bench press and back squat exercises
Measured: Through study completion, an average of 2 weeks
Bar velocity deplacement performed in 1 set at 65%1RM until task failure
In bench press and back squat exercises
Measured: Through study completion, an average of 2 weeks
Power output generated in 1 set at 65%1RM until task failure
In bench press and back squat exercise
Measured: Through study completion, an average of 2 weeks
Maximal Fat Oxidation Rate (MFO)
g/min (MFO) using a metabolic chart.
Measured: Through study completion, an average of 2 weeks
Resting Metabolic Rate (RMR)
Kcal at rest (RMR) using a metabolic chart.
Measured: Through study completion, an average of 2 weeks
Secondary outcomes (5)
Mood state (tension, depression, anger, vigor, fatigue and confusion)
Participants graded a set of 29 items related to the mood on a Likert scale from 0 (not at all) to 4 (extremely) in reply to the question: How do you feel at this moment? to assess six scales: tension, depression, anger, vigor, fatigue and confusion.
Measured: Through study completion, an average of 2 weeks
Adverse effects
perception of power, endurance, energy and exertion, as well as heart, muscular and gastrointestinal discomfort
Measured: Through study completion, an average of 2 weeks
handgrip and isometric mid-thigh pull tests
N generated
Measured: Through study completion, an average of 2 weeks
Vertical Jump (cm)
Measured: Through study completion, an average of 2 weeks
Vertical Jump (power)
Measured: Through study completion, an average of 2 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Sep 2024
- Study start1 Apr 2024
- Primary completion30 Jul 2025
- Study completion30 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CYP1A2 PolymorphismStudies 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
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Lead sponsor
- Alberto Pérez-López
- Sponsor type
- University, hospital or other
- Collaborators
- University of Alcala
- Responsible party
- Sponsor-investigator, Alberto Pérez-López, University of Alcala
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06610110
- Sponsor's protocol ID
- CEIP/2024/2/037
- Status last verified
- Aug 2025
- First submitted
- 9 Sep 2024
- Last updated
- 6 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 6 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Influence of CYP1A2 on the Acute Effect of Caffeine Intake on Resistance Exercise
- ClinicalTrials.gov ID
- NCT06610110
- Acronym / sponsor ID
- CEIP/2024/2/037
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- Alberto Pérez-LópezUniversity, hospital or other
- Collaborators
- University of Alcala
- Study start
- 1 Apr 2024 (actual)
- Primary completion
- 30 Jul 2025 (actual)
- Study completion
- 30 Jul 2025 (actual)
- First posted
- 24 Sep 2024 (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.
Introduction: Several studies have evaluated and confirmed the ergogenic effect of acute caffeine intake on sports performance, specifically on strength and power performance. However, it remains to be elucidated how CYP1A2 polymorphism influences the acute effects of caffeine on this type of exercise.
Objectives: The present study aims to analyze the effects of acute caffeine intake on muscular strength, power, and endurance performance according to CYP1A2 polymorphism in men and women.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 8
| Arm | Type | Receives |
|---|---|---|
| Genotype AA - Male - Caffeine | Experimental | Dietary Supplement: Caffeine |
| Genotype AC or CC - Male - Caffeine | Experimental | Dietary Supplement: Caffeine |
| Genotype AA - Male - Placebo | Placebo comparator | Dietary Supplement: Placebo |
| Genotype AC or CC - Male - Placebo | Placebo comparator | Dietary Supplement: Placebo |
| Genotype AA - Female - Caffeine | Experimental | Dietary Supplement: Caffeine |
| Genotype AC or CC - Female - Caffeine | Experimental | Dietary Supplement: Caffeine |
| Genotype AA - Female - Placebo | Placebo comparator | Dietary Supplement: Placebo |
| Genotype AC or CC - Female - Placebo | Placebo comparator | Dietary Supplement: Placebo |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Age between ≥ 18 and ≤ 35 years.
- Body mass index (BMI) lower than 25 kg/m².
- Physically active subjects (≥150 min/week of moderate exercise).
- Healthy men and women without neurological, cardiometabolic, immunological, or physical conditions that prevent them from performing physical exercise.
- Participants capable of performing the tests.
Key exclusion criteria (7 listed)
- History of neuromuscular, cardiac, or diseases that could affect liver or muscle metabolism.
- Use of drugs or other stimulants that interfere with caffeine intake and intestinal absorption during the tests and study.
- Body mass index (BMI) ≥ 25 kg/m².
- Having undergone prolonged periods of forced physical inactivity during the 6 months prior to the study.
- Performing strenuous exercise within 48 hours prior to the tests.
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 |
|---|---|---|
| CaffeineAcute caffeine intake (3 mg/kg) | Dietary supplement | Genotype AA - Female - Caffeine, Genotype AA - Male - Caffeine, Genotype AC or CC - Female - Caffeine, Genotype AC or CC - Male - Caffeine |
| PlaceboPlacebo (3 mg/kg maltodextrin) | Dietary supplement | Genotype AA - Female - Placebo, Genotype AA - Male - Placebo, Genotype AC or CC - Female - Placebo, Genotype AC or CC - Male - Placebo |
Primary outcome
cyp1a2 polymorphism
Time frame: Before the beginning of the trial
Using saliva sample and PCR
Mean velocity at different %1RM
Time frame: Through study completion, an average of 2 weeks
Measuring bar mean velocity desplacement during bench press and back squat exercises.
Peak velocity at different %1RM
Time frame: Through study completion, an average of 2 weeks
Measuring bar peak velocity and time to reach peak velocity of bar desplacement during bench press and back squat exercises.
Mean power output at different %1RM
Time frame: Through study completion, an average of 2 weeks
Measuring during bench press and back squat exercises.
Peak power output and time to reach peak power output at different %1RM
Time frame: Through study completion, an average of 2 weeks
Measuring during bench press and back squat exercises.
Number of repetitions performed in 1 set at 65%1RM until task failure
Time frame: Through study completion, an average of 2 weeks
In bench press and back squat exercises
Bar velocity deplacement performed in 1 set at 65%1RM until task failure
Time frame: Through study completion, an average of 2 weeks
In bench press and back squat exercises
Power output generated in 1 set at 65%1RM until task failure
Time frame: Through study completion, an average of 2 weeks
In bench press and back squat exercise
Maximal Fat Oxidation Rate (MFO)
Time frame: Through study completion, an average of 2 weeks
g/min (MFO) using a metabolic chart.
Resting Metabolic Rate (RMR)
Time frame: Through study completion, an average of 2 weeks
Kcal at rest (RMR) using a metabolic chart.
5 secondary outcomes
Mood state (tension, depression, anger, vigor, fatigue and confusion)
Time frame: Through study completion, an average of 2 weeks
Adverse effects
Time frame: Through study completion, an average of 2 weeks
handgrip and isometric mid-thigh pull tests
Time frame: Through study completion, an average of 2 weeks
Vertical Jump (cm)
Time frame: Through study completion, an average of 2 weeks
Vertical Jump (power)
Time frame: Through study completion, an average of 2 weeks
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 6 May 2026.
- Individual participant dataSharing planned: Yes
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.
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Caffeine in people with CYP1A2 Polymorphism and Caffeine and Resistance Exercise, run by Alberto Pérez-López at 2 sites in Spain.
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 5 inclusion and 7 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 6 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 2 sites in Spain. 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?
cyp1a2 polymorphism (time frame: Before the beginning of the trial). The study lists 10 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 6 May 2026.