CompletedNCT06606639Updated May 25, 2025

Reproducibility of Acute Caffeine Effect

An interventional study of Caffeine and Placebo in Caffeine and Resistance Exercise, sponsored by University of Alcala. Completed at 1 site in Spain. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-05-25.

Sponsored by University of Alcala · Not applicable, Interventional, and Other

From the registry’s dates

Registered 8 months after the study started (first participant enrolled Jan 2024, registered Sep 2024).

Phase: Not applicable
Study type: Interventional
Enrollment: 48
Allocation: Randomized
Ages: 18 Years to 35 Years
Sex: All

Study summary

Introduction: Various studies have evaluated and verified the ergogenic effect of acute caffeine intake on sports performance, specifically on strength and power performance. However, all experimental investigations designed so far have been based on the comparison of the \"caffeine\" and \"placebo\" conditions in a single trial, not considering the reproducibility and variability of caffeine in multiple trials.

Objectives: The present study aims to evaluate the reproducibility and replicability of the acute effect of caffeine intake on energy metabolism and the muscular production of force, power and endurance, according to sex (men vs women) and type of exercise ( bench press vs squat).

Conditions studied

Caffeine and Resistance Exercise

In context

Lead sponsor

University of Alcala is the lead sponsor of 123 studies on the registry; 36 are open to participants now.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years to 35 Years
Sexes eligible: All
Accepts healthy volunteers: Yes

Inclusion criteria

Age between ≥ 18 and ≤ 35 years.
Body Mass Index (BMI) \< 25 kg/m².
Resistance-trained individuals (\> 2 years of structured trained).
Healthy men and women without neurological, cardiometabolic, immunological, or physical conditions that prevent them from exercising.
Participants must be able to perform the tests described in the following section.

Exclusion criteria

Exclusion Criteria:

History of neuromuscular diseases, heart diseases, or diseases that may affect liver or muscle metabolism.
Use of drugs, other stimulants or sport supplements that interfere with the the study dietary supplement.
Sedentary habits (\<150 min/week of moderate exercise).
Having undergone prolonged periods of forced physical inactivity during the 6 months prior to the study.
Performing strenuous exercise during the 48 hours prior to the tests.
Failure to replicate the same food intake on the two days of the experiments.
Consuming caffeine or any other stimulant after 6 pm the day before the training or tests, to avoid headaches, discomfort, or lethargy among regular caffeine consumers.

Study design

Phase: Not applicable
Primary purpose: Other
Allocation: Randomized
Intervention model: Crossover assignment
Masking: Double (Participant, Investigator)
Enrollment: 48 participants (actual)

Study arms

Experimental
Caffeine - Trial 1
Dietary Supplement: Caffeine
Experimental
Caffeine - Trial 2
Dietary Supplement: Caffeine
Experimental
Caffeine - Trial 3
Dietary Supplement: Caffeine
Placebo comparator
Placebo - Trial 1
Dietary Supplement: Placebo
Placebo comparator
Placebo - Trial 2
Dietary Supplement: Placebo

Interventions

Dietary supplementCaffeine
acute caffeine intake (3 mg/kg)
Dietary supplementPlacebo
Acute placebo intake (3 mg/kg of maltodextrin)

What researchers measure

Primary outcomes

Mean velocity at different %1RM
Measuring bar mean velocity desplacement during bench press and back squat exercises.
Time frame: Through study completion, an average of 4 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.
Time frame: Through study completion, an average of 4 weeks
Mean power output at different %1RM
Measuring during bench press and back squat exercises.
Time frame: Through study completion, an average of 4 weeks
Peak power output and time to reach peak power output at different %1RM
Measuring during bench press and back squat exercises.
Time frame: Through study completion, an average of 4 weeks
Number of repetitions performed in 1 set at 65%1RM until task failure
In bench press and back squat exercises
Time frame: Through study completion, an average of 4 weeks
Bar velocity deplacement performed in 1 set at 65%1RM until task failure
In bench press and back squat exercises
Time frame: Through study completion, an average of 4 weeks
Power output generated in 1 set at 65%1RM until task failure
In bench press and back squat exercise
Time frame: Through study completion, an average of 4 weeks
Resting Metabolic Rate (RMR)
Kcal at rest measuring (RMR) using a metabolic chart.
Time frame: Through study completion, an average of 4 weeks
Maximal Fat Oxidation Rate (MFO)
g/min (MFO) using a metabolic chart.
Time frame: Through study completion, an average of 4 weeks

Secondary outcomes

Physical activity (METs-min/wk)
Using IPAQ
Time frame: Through study completion, an average of 4 weeks
Dietary (g/kg of macronutrients)
Using 24-total recall
Time frame: Through study completion, an average of 4 weeks
Mood state
Mood. 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.
Time frame: Through study completion, an average of 4 weeks
Adverse effects
Adverse effects. perception of power, endurance, energy and exertion, as well as heart, muscular and gastrointestinal discomfort.
Time frame: Through study completion, an average of 4 weeks
Fat mass
Using electrical bioimpedance (kg and % of body mass)
Time frame: Through study completion, an average of 4 weeks
Fat-free mass
Using electrical bioimpedance (kg and % of body mass)
Time frame: Through study completion, an average of 4 weeks

Study locations

1 site

Facultad de Medicina y Ciencias de la Salud. Universidad de Alcalá
Alcalá de Henares, Madrid 28805, Spain

References and documents

Individual participant data

Plan to share: Yes

No publications or documents are linked to this record.

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on May 25, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT06606639
Lead sponsor: University of Alcala
Responsible party: Alberto Pérez-López (Principal Investigator, University of Alcala) — Principal investigator
First posted: Sep 23, 2024
Start date: Jan 8, 2024
Primary completion: May 22, 2024
Completion: May 22, 2024
Last update: May 25, 2025

Oversight

Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in May 2025. You cannot join it, but the record below documents what was studied.

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