Caffeine
Conditions
Brief summary
Introduction: Several studies have evaluated and confirmed the ergogenic effects of acute caffeine intake on sports performance. However, some studies suggest that this effect predominantly occurs in large muscle groups, potentially due to increased skeletal muscle electrical activity. Objectives: This study aims to evaluate the acute effects of caffeine intake on strength, power, muscle endurance, and muscle electrical activity in young adults. It will also analyze the influence of circadian rhythms (morning vs. afternoon) on exercise performance (bench press vs. squat). Methods: Twelve healthy, physically active participants will be recruited for the study. Using a triple-blind, crossover, randomized, and controlled design, participants will ingest either caffeine (3 mg/kg body mass) or a placebo (maltodextrin, 3 mg/kg) 60 minutes before the trial. Muscular strength, power, and endurance performance will then be assessed through 1RM tests, and at 25%, 50%, 75%, and 90% of 1RM, along with muscle endurance tests at 65% of 1RM, for both squat and bench press exercises. EMG will be used to measure skeletal muscle electrical activity during the tests. The experimental sessions will be conducted in the morning (8:00 am to 10:00 am) and the afternoon (4:30 pm to 6:30 pm).
Interventions
DIETARY_SUPPLEMENTCaffeine
Acute caffeine intake (3 mg/kg)
DIETARY_SUPPLEMENTPlacebo
Acute placebo intake (3 mg/kg of maltodextrin)
Sponsors
University of Alcala
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
DOUBLE (Subject, Investigator)
Masking description
Statistician
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Age between 18 and 35 years. * Body Mass Index (BMI) < 25 kg/m². * Resistance-trained individuals (more than 2 years of structured training). * 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 disease, or conditions that may affect liver or muscle metabolism. * Use of drugs, stimulants, or sports supplements that could interfere with the dietary supplement used in the study. * Sedentary habits (less than 150 minutes/week of moderate exercise). * Having undergone prolonged periods of physical inactivity in the 6 months prior to the study. * Engaging in strenuous exercise within 48 hours prior to the tests. * Failure to replicate the same food intake on both experimental days. * Consumption of caffeine or any other stimulant after 6 pm on the day before the tests, to avoid headaches, discomfort, or lethargy in regular caffeine consumers.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle electrical activity (EMG). | Through study completion, an average of 4 weeks | Root-mean-square (RMS) and maximal voluntary contraction (MVC) from pectoralis major and triceps (bench press) and from rectus femoris and vastus lateralis (Back squat). |
| Bar velocity deplacement performed in 1 set at 65%1RM until task failure | Through study completion, an average of 4 weeks | In bench press and back squat exercises |
| Power output generated in 1 set at 65%1RM until task failure | Through study completion, an average of 4 weeks | In bench press and back squat exercise |
| Mean velocity at different %1RM | Through study completion, an average of 4 weeks | Measuring bar mean velocity desplacement during bench press and back squat exercises. |
| Peak velocity at different %1RM | Through study completion, an average of 4 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 | Through study completion, an average of 4 weeks | Measuring during bench press and back squat exercises. |
| Peak power output and time to reach peak power output at different %1RM | Through study completion, an average of 4 weeks | Measuring during bench press and back squat exercises. |
| Number of repetitions performed in 1 set at 65%1RM until task failure | Through study completion, an average of 4 weeks | — |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Adverse effects | Through study completion, an average of 4 weeks | perception of power, endurance, energy and exertion, as well as heart, muscular and gastrointestinal discomfort. |
| Mood state (tension, depression, anger, vigor, fatigue and confusion) | Through study completion, an average of 4 weeks | 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. |
Countries
Spain
Outcome results
None listed