Caffeine, CYPA12 and Resistance Exercise

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.

Study Overview

• Status: Completed
• Conditions: CYP1A2 Polymorphism; Caffeine and Resistance Exercise
• Intervention / Treatment: Dietary supplement: Caffeine; Dietary supplement: Placebo

• Study Type: Interventional
• Enrollment (Actual): 60
• 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
    • Alcalá de Henares, Madrid, Spain
      • 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) 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.

Exclusion Criteria:

• 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.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

8

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Genotype AA - Male - Caffeine	Dietary supplement: Caffeine; Acute caffeine intake (3 mg/kg)
Experimental: Genotype AC or CC - Male - Caffeine	Dietary supplement: Caffeine; Acute caffeine intake (3 mg/kg)
Placebo Comparator: Genotype AA - Male - Placebo	Dietary supplement: Placebo; Placebo (3 mg/kg maltodextrin)
Placebo Comparator: Genotype AC or CC - Male - Placebo	Dietary supplement: Placebo; Placebo (3 mg/kg maltodextrin)
Experimental: Genotype AA - Female - Caffeine	Dietary supplement: Caffeine; Acute caffeine intake (3 mg/kg)
Experimental: Genotype AC or CC - Female - Caffeine	Dietary supplement: Caffeine; Acute caffeine intake (3 mg/kg)
Placebo Comparator: Genotype AA - Female - Placebo	Dietary supplement: Placebo; Placebo (3 mg/kg maltodextrin)
Placebo Comparator: Genotype AC or CC - Female - Placebo	Dietary supplement: Placebo; Placebo (3 mg/kg maltodextrin)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
cyp1a2 polymorphism	Using saliva sample and PCR	Before the beginning of the trial
Mean velocity at different %1RM	Measuring bar mean velocity desplacement during bench press and back squat exercises.	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.	Through study completion, an average of 2 weeks
Mean power output at different %1RM	Measuring during bench press and back squat exercises.	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.	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	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	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	Through study completion, an average of 2 weeks
Maximal Fat Oxidation Rate (MFO)	g/min (MFO) using a metabolic chart.	Through study completion, an average of 2 weeks
Resting Metabolic Rate (RMR)	Kcal at rest (RMR) using a metabolic chart.	Through study completion, an average of 2 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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	Through study completion, an average of 2 weeks
handgrip and isometric mid-thigh pull tests	N generated	Through study completion, an average of 2 weeks
Vertical Jump (cm)		Through study completion, an average of 2 weeks
Vertical Jump (power)		Through study completion, an average of 2 weeks

Collaborators and Investigators

• Sponsor: Alberto Pérez-López
• Collaborators: University of Alcala

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2024
• Primary Completion (Actual): July 30, 2025
• Study Completion (Actual): July 30, 2025

Study Registration Dates

• First Submitted: September 9, 2024
• First Submitted That Met QC Criteria: September 19, 2024
• First Posted (Actual): September 24, 2024

Study Record Updates

• Last Update Posted (Actual): May 6, 2026
• Last Update Submitted That Met QC Criteria: April 30, 2026
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Alkaloids; Purinones; Purines; Xanthines; Caffeine
• Other Study ID Numbers: CEIP/2024/2/037

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