Effect of Acute Caffeine and Beetroot Juice Intake on Strength, Power, and Muscular Endurance (CAF+BJ)

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

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).

Study Overview

• Status: Completed
• Conditions: Nitrates; Caffeine; Resistance Exercise; Dietary Supplements; Sports Performance
• Intervention / Treatment: Dietary supplement: Acute caffeine and beetroot juice; Dietary supplement: Acute beetroot juice; Dietary supplement: Acute caffeine; Dietary supplement: Placebo

• Study Type: Interventional
• Enrollment (Actual): 14
• 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 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.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Caffeine + Beetroot Juice; 70 mL of concentrated NO3--rich (BJ, 6.5 mmol NO3-) + 3 mg/kg of caffeine	Dietary supplement: Acute caffeine and beetroot juice; Combined effect of beetroot juice and caffeine intake on muscular strength, power and endurance performance
Experimental: Beetroot Juice; 70 mL of concentrated NO3--rich (BJ, 6.5 mmol NO3-) + 3 mg/kg of placebo (maltodextrin)	Dietary supplement: Acute beetroot juice; single effect of beetroot juice intake on muscular strength, power and endurance performance
Experimental: Caffeine; 70 mL of NO3--depleted (BJ, 0.04 mmol NO3-) + 3 mg/kg of caffeine	Dietary supplement: Acute caffeine; single effect of caffeine intake on muscular strength, power and endurance performance
Placebo Comparator: Placebo; 70 mL of NO3--depleted (BJ, 0.04 mmol NO3-) + 3 mg/kg of placebo (maltodextrin)	Dietary supplement: Placebo; single effect of placebo on muscular strength, power and endurance performance

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean and peak velocity and time to reach peak velocity at different %1RM	Measuring bar velocity desplacement during bench press and back squat exercises.	On each trial, after dietary supplement intake, during 2 weeks
Mean and peak power output and time to reach peak power output at different %1RM	Measuring power output generated during bench press and back squat exercises.	On each trial, after dietary supplement intake, during 2 weeks
Number of repetitions performed at 65%1RM until task failure	Additionally to mean and peak velocity, mean and peak power output, time to reach peak velocity and peak power	On each trial, after dietary supplement intake, during 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.	On each trial, after dietary supplement intake, during 2 weeks
Adverse effects	perception of power, endurance, energy and exertion, as well as heart, muscular and gastrointestinal discomfort.	On each trial, after dietary supplement intake, during 2 weeks
handgrip and isometric mid-thigh pull tests	N generated	On each trial, after dietary supplement intake, during 2 weeks
Vertical Jump (cm and power)		On each trial, after dietary supplement intake, during 2 weeks

Collaborators and Investigators

• Sponsor: University of Alcala

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2023
• Primary Completion (Actual): January 30, 2024
• Study Completion (Actual): May 1, 2024

Study Registration Dates

• First Submitted: September 6, 2024
• First Submitted That Met QC Criteria: September 10, 2024
• First Posted (Estimated): September 19, 2024

Study Record Updates

• Last Update Posted (Estimated): September 19, 2024
• Last Update Submitted That Met QC Criteria: September 10, 2024
• Last Verified: September 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Purinergic Antagonists; Purinergic Agents; Phosphodiesterase Inhibitors; Purinergic P1 Receptor Antagonists; Central Nervous System Stimulants; Caffeine
• Other Study ID Numbers: CEIP/2023/4/093

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