The goal of this clinical trial was to evaluate how acute intake of beetroot juice, caffeinated coffee, and their combination affected aerobic and anaerobic exercise performance in healthy recreationally active men. The main questions were: Did beetroot juice, caffeinated coffee, or their combination improve aerobic exercise performance? Did beetroot juice, caffeinated coffee, or their combination improve countermovement jump performance? Researchers compared four conditions: control, caffeinated coffee, beetroot juice, and beetroot juice combined with caffeinated coffee. Each participant completed all four conditions in a randomized crossover design, with a 1-week washout period between sessions. Participants: Completed a familiarization session before the experimental sessions Consumed water only, caffeinated Turkish coffee, beetroot juice, or both beetroot juice and caffeinated coffee depending on the assigned condition Performed a countermovement jump test Performed a 20-m multistage shuttle run test Had heart rate and rating of perceived exertion assessed during exercise testing
Before each experimental session, participants were instructed to maintain their habitual diet and training routine and to avoid strenuous exercise, alcohol, caffeine-containing foods and beverages, and ergogenic aids during the preceding 24 hours. Compliance with these instructions was confirmed before testing. Participants completed a familiarization session 2 days before the first experimental session. All exercise assessments were conducted in the morning using the same standardized warm-up and test order. Countermovement jump testing was performed before the 20-m multistage shuttle run test.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
16
Participants consumed 70 mL of concentrated beetroot juice providing 6.5 mmol of nitrate according to the manufacturer's specification. The beetroot juice was consumed approximately 2.5 hours before exercise testing.
Turkish coffee was individually prepared to provide an estimated caffeine dose of 4 mg/kg body mass. The caffeine dose was calculated using an estimated caffeine content of 17 mg/g of coffee. Approximately 14-20 g of coffee was prepared with 100 mL of water and consumed approximately 60 minutes before exercise testing.
During the control condition, participants received no experimental supplement and consumed water only before completing the standardized exercise testing protocol.
Acibadem Sports Athlete Health Center
Istanbul, Istanbul, Turkey (Türkiye)
Estimated Maximal Oxygen Uptake (VO₂max)
Estimated VO2max (mL/kg/min) was calculated from the maximal running speed achieved during the 20-m multistage shuttle run test using the predefined equation.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Maximal Running Speed
Highest running speed (km/h) achieved during the 20-m multistage shuttle run test.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Number of Completed Shuttles
Total number of successfully completed 20-m shuttles during the multistage shuttle run test.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Total Distance Covered
Total distance (m) completed during the 20-m multistage shuttle run test.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Countermovement Jump Height
Maximum countermovement jump height (cm) obtained from three trials using a dual force-platform system. The highest value was used.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Countermovement Jump Peak Power
Peak power (W) recorded during the countermovement jump assessment.
Time frame: At each of the four experimental sessions; sessions were separated by a 1-week washout period.
Mean Heart Rate
Mean heart rate (beats/min) recorded during exercise testing.
Time frame: During exercise testing at each of the four experimental sessions.
Maximum Heart Rate
Maximum heart rate (beats/min) recorded during exercise testing.
Time frame: During exercise testing at each of the four experimental sessions.
Rating of Perceived Exertion
Rating of perceived exertion assessed using the Borg 6-20 scale.
Time frame: Immediately after exercise testing at each of the four experimental sessions.
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