Acute Effects of Beetroot Juice and Caffeine Co-ingestion on Lower-limb Strength and Muscular Endurance in Females

Effect of Beetroot Juice Supplements with Caffeine Co-ingestion on Lower-limb Strength in Females

The aim of this study is to evaluate the acute effects of beetroot juice and caffeine, consumed individually or in combination, on lower-limb strength and muscular endurance in physically active women. The main questions it aims to answer are:

• Does the co-ingestion of beetroot juice and caffeine enhance lower-limb strength and muscular endurance more than either substance alone or a placebo?
• How do the acute effects of beetroot juice interact with caffeine on physical performance?

The study was conducted using a randomized, crossover design to evaluate the following four conditions:

Beetroot juice with placebo Caffeine with placebo Beetroot juice with caffeine Placebo only

Each participant completed all conditions, with a sufficient washout period between sessions to eliminate potential carryover effects. This design allowed for a direct comparison of the acute effects of each supplementation strategy on lower-limb strength and muscular endurance.

Participant Protocol

Participants consumed their assigned supplement on a single testing day for each condition. After supplementation, they performed standardized tests to measure lower-limb strength and muscular endurance. Progress was monitored, and data from all conditions were collected to assess the acute effects of each intervention.

Study Overview

• Status: Completed
• Conditions: Caffeine; Placebo; Beetroot Juice; Beetroot Juice with Caffeine Co-ingestion
• Intervention / Treatment: Dietary supplement: Beetroot juice combined with caffeine (COM); Dietary supplement: Beetroot juice placebo with caffeine (CAF); Dietary supplement: Beetroot juice with caffeine placebo (BRJ); Other: Beetroot placebo with caffeine placebo (PLA)

• Study Type: Interventional
• Enrollment (Actual): 15
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Spain
  • Córdoba, Spain, 14004
    • Edificio IMIBIC Avda Menéndez Pidal s/n

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Minimal experience of six months of strength training
• Be familiarized with the exercise test: counter movement jump (CMJ), barbell back squats, leg press and knee extension.

Exclusion Criteria:

• Supplementation consumption
• Sports injuries

Study Plan

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: COM; Beetroot juice combined with caffeine	Dietary supplement: Beetroot juice combined with caffeine (COM); 70 mL of beetroot juice (400 mg NO3-, BEET It Sport; James White Drinks Ltd) 120 minutes before experimental session; 200 mg caffeine capsule from the IO.GENIX Nutrition brand (Toledo, Spain) 60 minutes before experimental session
Active Comparator: CAF; Beetroot juice placebo with caffeine	Dietary supplement: Beetroot juice placebo with caffeine (CAF); - 70 mL of a blackcurrant beverage, which depletes NO3- (Capri-Sun) 120 minutes before experimental session - 200 mg caffeine capsule from the IO.GENIX Nutrition brand (Toledo, Spain) 60 minutes before experimental session
Active Comparator: BRJ; Beetroot juice with caffeine placebo	Dietary supplement: Beetroot juice with caffeine placebo (BRJ); - 70 mL of beetroot juice (400 mg NO3-, BEET It Sport; James White Drinks Ltd) 120 minutes before experimental session - Multivitamin capsule from NaturrTierra (Leganés, Spain) 60 minutes before experimental session
Placebo Comparator: PLA; Beetroot juice placebo with caffeine placebo	Other: Beetroot placebo with caffeine placebo (PLA); - 70 mL of a blackcurrant beverage, which depletes NO3- (Capri-Sun) 120 minutes before experimental session - Multivitamin capsule from NaturrTierra (Leganés, Spain) 60 minutes before experimental session

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change of height reached in jump	Evaluated through Countermovement jump test with a recovery period of 45 seconds between jumps. The height reached was recorded in centimeters.	Visit 1 (Day 1), Visit 2 (Day 5), Visit 3 (Day 9), Visit 4 (Day 13)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Movement velocity	The velocity was recorded in meters per second (m/s) during two repetitions of the back squat, evaluated at 50% and 75% of the repetition maximum (RM).	Visit 1 (Day 1), Visit 2 (Day 5), Visit 3 (Day 9), Visit 4 (Day 13)
Muscular endurance test	The test consists of three exercises: back squat, leg press and leg extension. Three series will be performed until concentric failure at 75% RM, three minutes of rest between each series (3 series). The number of repetitions was recorded.	Visit 1 (Day 1), Visit 2 (Day 5), Visit 3 (Day 9), Visit 4 (Day 13)
Rating of perceived exertion (RPE).	Immediately at the end of the muscular endurance test, participants will be instructed to report their RPE using a scale 1-10 (worse to better outcome).	Visit 1 (Day 1), Visit 2 (Day 5), Visit 3 (Day 9), Visit 4 (Day 13)

Collaborators and Investigators

• Sponsor: Jose Manuel Jurado Castro

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2024
• Primary Completion (Actual): December 26, 2024
• Study Completion (Actual): December 26, 2024

Study Registration Dates

• First Submitted: December 26, 2024
• First Submitted That Met QC Criteria: December 26, 2024
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 3, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Keywords: caffeine; dietary supplement; female; resistance training; nitrate; beetroot juice
• 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: IMIBIC_BRJ_CAF

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

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