Reproducibility of Acute Caffeine Effect

Reproducibility of the Acute Effect of Caffeine on Energy Metabolism and Muscular Strength, Power and Endurance Performance

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).

Study Overview

• Status: Completed
• Conditions: Caffeine and Resistance Exercise
• Intervention / Treatment: Dietary supplement: Placebo; Dietary supplement: Caffeine

• Study Type: Interventional
• Enrollment (Actual): 48
• Phase: Not Applicable

Contacts and Locations

Study Locations

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

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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:

• 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 Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Caffeine - Trial 1	Dietary supplement: Caffeine; acute caffeine intake (3 mg/kg)
Experimental: Caffeine - Trial 2	Dietary supplement: Caffeine; acute caffeine intake (3 mg/kg)
Experimental: Caffeine - Trial 3	Dietary supplement: Caffeine; acute caffeine intake (3 mg/kg)
Placebo Comparator: Placebo - Trial 1	Dietary supplement: Placebo; Acute placebo intake (3 mg/kg of maltodextrin)
Placebo Comparator: Placebo - Trial 2	Dietary supplement: Placebo; Acute placebo intake (3 mg/kg of maltodextrin)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean velocity at different %1RM	Measuring bar mean velocity desplacement during bench press and back squat exercises.	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.	Through study completion, an average of 4 weeks
Mean power output at different %1RM	Measuring during bench press and back squat exercises.	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.	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	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	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	Through study completion, an average of 4 weeks
Resting Metabolic Rate (RMR)	Kcal at rest measuring (RMR) using a metabolic chart.	Through study completion, an average of 4 weeks
Maximal Fat Oxidation Rate (MFO)	g/min (MFO) using a metabolic chart.	Through study completion, an average of 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Physical activity (METs-min/wk)	Using IPAQ	Through study completion, an average of 4 weeks
Dietary (g/kg of macronutrients)	Using 24-total recall	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.	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.	Through study completion, an average of 4 weeks
Fat mass	Using electrical bioimpedance (kg and % of body mass)	Through study completion, an average of 4 weeks
Fat-free mass	Using electrical bioimpedance (kg and % of body mass)	Through study completion, an average of 4 weeks

Collaborators and Investigators

• Sponsor: University of Alcala

Study record dates

Study Major Dates

• Study Start (Actual): January 8, 2024
• Primary Completion (Actual): May 22, 2024
• Study Completion (Actual): May 22, 2024

Study Registration Dates

• First Submitted: September 9, 2024
• First Submitted That Met QC Criteria: September 18, 2024
• First Posted (Actual): September 23, 2024

Study Record Updates

• Last Update Posted (Actual): May 25, 2025
• Last Update Submitted That Met QC Criteria: May 23, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Neurotransmitter Agents; Purinergic Antagonists; Purinergic Agents; Central Nervous System Stimulants; Phosphodiesterase Inhibitors; Purinergic P1 Receptor Antagonists; Caffeine
• Other Study ID Numbers: CEID/2024/2/039

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No