An interventional study of Caffeine (Guinama Anhydrous Powder) and Caffeine (Nescafé Classic Coffee) in Fat Metabolism, Caffeine and Cycling, sponsored by Universidad Rey Juan Carlos. Enrolling by invitation at 1 site in Spain. Open to participants aged 18 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-29.
Sponsored by Universidad Rey Juan Carlos · Not applicable, Interventional, and Basic science
Among 13 studies testing caffeine in Motor Activity — 2 open to participants now, 2 under way, none of them phase 3. Caffeine · Motor Activity.
Among the 13 studies testing caffeine in Motor Activity, this one is the 12th largest by planned enrollment, is the only one that started in 2026, is one of 11 with no phase, and was the 10th registered.
9,798 studies on the registry are indexed under Motor Activity; 1,910 are open to participants now.
This study's planned enrollment of 10 is below the median of 60 across 8,388 interventional studies indexed under Motor Activity.
Browse Motor Activity studies →2 of the 13 studies testing caffeine in Motor Activity are open now, in 2 countries. Each count lists the studies.
Caffeine: first FDA approval 1948 (CAFERGOT), first EMA approval 2009. What it is approved for, and how studies give it, is on its page →
Of the 1,201 Motor Activity studies recruiting now, 517 (43%) set no upper age limit and 535 (45%) stop at 75 or younger; 180 take children under 18; 420 take healthy volunteers.
This study: 18 Years to 50 Years · all sexes · healthy volunteers too.
The full table on the hub →13 studies; the count open now beside each. This study's row is marked.
First in 2010; this study’s year is marked. 1 started in 2026.
Median enrollment 23 across the 13 interventional studies. Of the 10 that completed or were terminated, 0 (0%) have results posted.
None of the 13 has an industry lead sponsor. The 10 most frequent:
Universidad Rey Juan Carlos is the lead sponsor of 114 studies on the registry; 24 are open to participants now.
Universidad Rey Juan Carlos has 9 studies filed under Motor Activity — fewer than ten, so there is no comparison to draw.
None of the studies under way reaches primary completion within a year.
Among the 13 studies testing caffeine in Motor Activity, from their registry updates:
The goal of this clinical trial is to learn if different forms of caffeine ingestion can influence fat oxidation during submaximal cycling exercise. The study will recruit healthy adults, both men and women, aged 18 to 50, who regularly perform aerobic exercise. The main questions it aims to answer are:
Researchers will compare each caffeine form to its corresponding placebo to determine their effects on fat oxidation and other physiological outcomes.
Participants will:
All sessions will be conducted under controlled laboratory conditions with standardized protocols to ensure safety and reliable measurements.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will ingest 3 mg/kg of anhydrous caffeine powder in an opaque capsule 60 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Drug: Caffeine (Guinama Anhydrous Powder)
Participants will ingest an opaque capsule filled with cellulose (placebo) 60 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Other: Placebo (Cellulose Capsule)
Participants will consume 3 mg/kg of caffeine via soluble coffee (Nescafé Classic) in 250 mL of hot water 60 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Dietary Supplement: Caffeine (Nescafé Classic Coffee)
Participants will consume decaffeinated soluble coffee (Nescafé Descafeinado) in 250 mL of hot water 60 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Other: Placebo (Decaffeinated Coffee)
Participants will chew caffeinated gum (Kafewake) containing 3 mg/kg of caffeine for 10 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Dietary Supplement: Caffeine (Kafewake Gum)
Participants will chew non-caffeinated gum (Kafewake) with identical flavor and texture for 10 minutes before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Other: Placebo (Non-caffeine Gum)
Participants will perform a 20-second mouth rinse with 25 mL of water containing 3 mg/kg of caffeine from soluble coffee (Nescafé Classic) before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Other: Caffeine Mouth Rinse Solution
Participants will perform a 20-second mouth rinse with 25 mL of water containing decaffeinated soluble coffee (Nescafé descafeinado) before performing 60 minutes of cycling on a cycle ergometer at Fatmax intensity.
Other: Placebo Mouth Rinse Solution
3 mg/kg of anhydrous caffeine powder (Guinama, Spain) administered in an opaque capsule 60 min before exercise.
3 mg/kg of caffeine via Nescafé Classic (Nestlé, Switzerland) dissolved in 250 mL of water 60 min before exercise.
3 mg/kg of caffeine via Kafewake gum (Arafarma group, Spain), chewed for 10 min before exercise.
3 mg/kg of caffeine (Nescafé Classic) dissolved in 25 mL of water for a 20-second rinse before exercise.
Opaque capsule containing cellulose powder, matching caffeine capsules, taken 60 min before exercise.
Decaffeinated Nescafé (Nestlé, Switzerland) in 250 mL of water, matching caffeinated coffee, taken 60 min before.
Kafewake Non-caffeinated gum (Arafarma group, Spain) with identical taste and texture, chewed for 10 min before.
Decaffeinated Nescafé in 25 mL of water for a 20-second rinse immediately before exercise.
Rate of fat oxidation during submaximal cycling exercise at Fatmax intensity
Continuous measurement of fat oxidation using indirect calorimetry during 1-hour cycling at Fatmax intensity. Calculated from respiratory gas exchange (VO₂ and VCO₂) using Frayn's equations. Unit of Measure: grams per minute (g/min).
Time frame: 1 hour per experimental session
Rate of carbohydrate oxidation during submaximal cycling exercise at Fatmax intensity
Continuous measurement of carbohydrate oxidation using indirect calorimetry during 1-hour cycling at Fatmax intensity. Calculated from respiratory gas exchange (VO₂ and VCO₂) using Frayn's equations. Unit of Measure: grams per minute (g/min).
Time frame: 1 hour per experimental session
Total energy expenditure during exercise
Estimated from indirect calorimetry data using Brouwer's equation, recorded continuously during 1-hour cycling at Fatmax intensity. Unit of Measure: kilocalories per minute (kcal/min).
Time frame: 1 hour per experimental session
Mean Exercise Heart Rate
Heart rate monitored continuously via a chest strap (Polar H9, Polar Electro, Findland) during the exercise test. Unit of Measure: beats per minute (bpm).
Time frame: 1 hour per experimental session
Oxygen consumption
Volume of oxygen consumed during the exercise session measured breath-by-breath via indirect calorimetry using the Ergostik gas analyzer (Geratherm Respiratory GmbH, Germany). Unit of Measure: Liters per minute (L/min).
Time frame: 1 hour per experimental session
Carbon Dioxide Production
Volume of carbon dioxide produced during the exercise session measured breath-by-breath via indirect calorimetry using the Ergostik gas analyzer (Geratherm Respiratory GmbH, Germany). Unit of Measure: Liters per minute (L/min).
Time frame: 1 hour per experimental session
Blood lactate concentration
Measured from capillary blood samples taken from the fingertip during exercise to assess metabolic response to different caffeine interventions. Unit of measure: Millimoles per liter (mmol/L).
Time frame: Every 20 minutes during each 1-hour session
Rating of Perceived Exertion (RPE) during exercise
Assessed using Borg's 6-20 scale; participants report perceived exertion at regular intervals. Unit of Measure: Units on a scale (from 6 to 20).
Time frame: Every 10 minutes during each 1-hour session
Occurrence of caffeine-related side effects
Structured questionnaire assessing symptoms commonly associated with caffeine intake, such as nervousness, tremors, insomnia, gastrointestinal discomfort, and increased heart rate.
Time frame: Immediately after each session and 24 hours post-exercise
Plan to share: Yes — De-identified individual participant data underlying the results reported in publications may be made available upon reasonable request. These data may include anonymized metabolic, ventilatory, cardiovascular and perceptual variables collected during the study (e.g., fat oxidation rate, energy expenditure, VO₂, VCO₂, heart rate, capillary blood lactate concentration, and ratings of perceived exertion). Any data sharing will be subject to ethical approval, compliance with applicable data protection regulations, and approval by the study investigators.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: De-identified individual participant data may be shared after the publication of the main study findings and will remain available for up to three years following publication.
Access criteria: Access to any de-identified individual participant data will be considered on a case-by-case basis. Requests will require a scientifically sound proposal and may be subject to additional ethical review and data use agreements, in accordance with institutional and legal requirements. The study investigators reserve the right to decline requests.
Data sharing details ↗ · www.urjc.es
Started Mar 2026 (actual). Primary completion is estimated for Jul 2026, 4 months after the start.
Of 5,147 non-industry interventional studies with no phase under Motor Activity, half reached primary completion within 17 months of starting (the median), counting those still running; a quarter within 7 and three quarters within 36. This study's planned 4 months is below that.
Counting every sponsor, half of 5,207 studies reached it within 17 months; a quarter within 7 and three quarters within 36.
How these figures are worked out, and which studies are left out of them.
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No contact was published for this record. The registry link below has the sponsor’s details.
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Studies of the drug tested here: Caffeine