Exercise Physiology, Sports Nutrition, Cardiorespiratory Fitness
Conditions
Keywords
Beetroot juice, Dietary nitrate, Aerobic performance, Muscle oxygenation, Female soccer players
Brief summary
Effects of Acute Beetroot Juice on Aerobic Performance and Muscle Oxygenation in Amateur Female Soccer Players
Detailed description
This randomized, double-blind, placebo-controlled crossover study evaluated the acute effects of nitrate-rich beetroot juice supplementation on aerobic performance, muscle oxygenation, and selected physiological responses in amateur female soccer players. Thirteen participants completed two experimental conditions in randomized order, separated by a 7-day washout period. In one condition, participants consumed 70 mL of nitrate-rich beetroot juice containing 6.4 mmol of nitrate, while in the other condition they consumed an equal volume of low-nitrate blackcurrant placebo containing \<0.1 mmol of nitrate. Each beverage was consumed 2.5 hours before exercise testing. Aerobic performance was assessed using a treadmill-adapted 12-minute Cooper test. Total distance covered and estimated maximal oxygen uptake (VO₂max) were evaluated as performance outcomes. Muscle oxygen saturation was monitored using near-infrared spectroscopy. Heart rate, blood pressure, blood glucose, and rating of perceived exertion were also assessed at predefined time points. Participants and investigators conducting the experimental procedures were blinded to the supplementation condition, and the supplementation sequence was generated by an independent researcher who was not involved in the experimental procedures or statistical analyses.
Interventions
DIETARY_SUPPLEMENTNitrate-rich beetroot juice
Participants consumed a single 70 mL dose of nitrate-rich beetroot juice (Beet It Pro Elite Shot, James White Drinks Ltd., Ipswich, UK) containing 6.4 mmol (approximately 400 mg) of nitrate. The supplement was ingested 2.5 hours before the 12-minute exercise test.
OTHERLow-nitrate blackcurrant placebo beverage
Participants consumed a single 70 mL dose of low-calorie blackcurrant beverage (Pfanner, Austria) containing negligible nitrate (\<0.1 mmol). The placebo was ingested 2.5 hours before the 12-minute exercise test.
Sponsors
Sakarya Applied Sciences University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
DOUBLE (Subject, Investigator)
Masking description
Participants and investigators conducting the experimental procedures were blinded to the supplementation condition. Supplementation order was generated by an independent researcher who was not involved in the experimental procedures or statistical analyses.
Intervention model description
Participants completed both intervention conditions in randomized order. Each participant received beetroot juice in one period and placebo in the other, with a 7-day washout period between conditions.
Eligibility
Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Female * Aged 18 years or older * Licensed soccer player for at least 3 years
Exclusion criteria
* Use of pharmacological treatment or supplements/ergogenic aids that could affect exercise performance, including stimulants such as caffeine * Presence of musculoskeletal, ligament, bone, neurological, or joint pathology incompatible with the exercise protocol * Current cardiovascular problems * Participation in additional sports or physical activities during the study period that could affect the study outcomes
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Distance Covered During the 12-Minute Cooper Test | During the 12-minute exercise test performed 2.5 hours after supplementation in each crossover condition | Total distance covered, expressed in meters, during a self-paced treadmill-adapted 12-minute Cooper test. Participants were instructed to cover the greatest possible distance within 12 minutes and were allowed to adjust treadmill speed throughout the test. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Estimated Maximal Oxygen Uptake (VO₂max) | At completion of the 12-minute exercise test performed 2.5 hours after supplementation in each crossover condition. | Estimated maximal oxygen uptake (VO₂max), expressed as mL·kg-¹·min-¹, was calculated from the total distance covered during the treadmill-adapted 12-minute Cooper test using the classical Cooper equation. |
| Muscle Oxygen Saturation (SmO₂) | Baseline (2 minutes before warm-up), during the 12-minute exercise test, and early post-exercise (approximately 2-3 minutes after exercise) in each crossover condition. | Muscle oxygen saturation (SmO₂), expressed as a percentage, was assessed in the vastus lateralis using near-infrared spectroscopy (Moxy Monitor, Fortiori Design LLC, Spicer, MN, USA). |
| Heart Rate | Pre-exercise, continuously during the 12-minute exercise test, approximately 2-3 minutes post-exercise, and approximately 29-30 minutes post-exercise in each crossover condition. | Heart rate, expressed as beats per minute, was recorded using a Polar V800 heart rate monitor. Values were summarized as the 1-minute pre-exercise mean, mean heart rate during the 12-minute exercise test, and recovery heart rate. |
| Blood Pressure | Before supplementation, pre-exercise, 3 minutes post-exercise, and 30 minutes post-exercise in each crossover condition. | Blood pressure, expressed in mmHg, was measured using an automated blood pressure monitor (Omron M2, Omron Healthcare Co., Kyoto, Japan). Three consecutive readings were obtained at each time point and averaged. |
| Blood Glucose | Immediately before supplementation, pre-exercise (2 minutes before warm-up), and immediately post-exercise in each crossover condition. | Capillary blood glucose, expressed in mg/dL, was measured from a finger-prick blood sample using a portable glucose analyzer (Plusmed Accuro, Taiwan). |
| Rating of Perceived Exertion (RPE) | Baseline and immediately post-exercise in each crossover condition. | Rating of perceived exertion was assessed using the Borg 6-20 scale, where higher scores indicate greater perceived exertion. |
Countries
Turkey (Türkiye)
Contacts
PRINCIPAL_INVESTIGATORMELIKE N EROGLU
Sakarya Applied Sciences University
Outcome results
None listed