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Completed

NCT Number: NCT06596395

Effect of Acute Caffeine and Beetroot Juice Intake on Strength, Power, and Muscular Endurance

Introduction: Several studies have evaluated and confirmed the ergogenic effect of acute caffeine and beetroot juice intake on sports performance. However, there are few studies focused on the production of strength, power, and muscle endurance, particularly when both supplements are ingested together.

Objectives: Evaluate the acute effect of combined and isolated intake of caffeine and beetroot juice on the production of strength, power, and muscle endurance in young adults, analyzing the effect of circadian rhythms (morning vs. afternoon) on the exercise performed (bench press vs. squat).

Methods: A total of 12 healthy and physically active participants will be recruited for the study. Through a double-blind, crossover, randomized, and controlled design, participants will ingest: a) Caffeine (3 mg/kg body mass); b) Beetroot juice (70 ml, 6.5 mmol of nitrates); c) Caffeine + Beetroot juice; d) Placebo (maltodextrin, 3 mg/kg). The supplements will be ingested 120 minutes (beetroot juice or placebo) and 60 minutes before (caffeine or placebo), the latter dissolved in 200 ml of water. After the ingestion period, strength, power, and muscle endurance will be analyzed with 1RM tests, strength and power tests at 25%, 50%, 75%, and 90% 1RM, and muscle endurance tests at 65% 1RM, in all cases for squat and bench press exercises. Additionally, dynamometry (manual and the isometric mid-thigh pull test) and vertical jump (squat jump and countermovement jump) will be analyzed. The four experimental conditions will be conducted in the morning (8:00 am to 10:00 am) and in the afternoon (4:30 pm to 6:30 pm).

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Key information

Conditions

Dietary Supplements Caffeine Nitrates Resistance Exercise Sports Performance

Age range

18 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Facultad de Medicina y Ciencias de la Salud. Universidad de Alcalá

Alcalá de Henares, Madrid, 28805, Spain

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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 intake of the study's dietary supplements.
  • 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.
  • Consuming foods rich in NO3- (e.g., beetroot, spinach, or celery) during the 48 hours prior to each experimental condition.

Treatment and study plan

Acute caffeine and beetroot juice

Dietary Supplement

Combined effect of beetroot juice and caffeine intake on muscular strength, power and endurance performance

Acute caffeine

Dietary Supplement

single effect of caffeine intake on muscular strength, power and endurance performance

Acute beetroot juice

Dietary Supplement

single effect of beetroot juice intake on muscular strength, power and endurance performance

Placebo

Dietary Supplement

single effect of placebo on muscular strength, power and endurance performance

Primary outcomes

  1. Mean and peak velocity and time to reach peak velocity at different %1RM

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

    Measuring bar velocity desplacement during bench press and back squat exercises.

  2. Mean and peak power output and time to reach peak power output at different %1RM

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

    Measuring power output generated during bench press and back squat exercises.

  3. Number of repetitions performed at 65%1RM until task failure

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

    Additionally to mean and peak velocity, mean and peak power output, time to reach peak velocity and peak power

Secondary outcomes

  1. Mood state (tension, depression, anger, vigor, fatigue and confusion)

    Time frame: On each trial, after dietary supplement intake, during 2 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.

  2. Adverse effects

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

    perception of power, endurance, energy and exertion, as well as heart, muscular and gastrointestinal discomfort.

  3. handgrip and isometric mid-thigh pull tests

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

    N generated

  4. Vertical Jump (cm and power)

    Time frame: On each trial, after dietary supplement intake, during 2 weeks

Sponsors and collaborators

Lead sponsor

University of Alcala

Other

Registry information

Official study title

Effect of Acute Caffeine and Beetroot Juice Intake on Strength, Power, and Muscular Endurance Based on Circadian Rhythms.

Acronym: CAF+BJ

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Sep 19, 2024
Registry last updated
Sep 19, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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