The Effects of Acute and Chronic Beetroot Juice Supplementation on Exercise Economy and Time Trial Performance in Recreationally Active Females
Bibliographic record
Abstract
Introduction Beetroot juice (BRJ) is a nutritional supplement that has received widespread attention over the last decade. Dietary nitrate (NO 3 − ) reduces the oxygen cost of submaximal exercise and improves performance in recreationally active males both acutely and chronically. The ergogenic effects of BRJ have been attributed to its high nitrate content. However, the evidence supporting the effects of BRJ in females is lacking. Purpose To investigate the effects of acute and chronic BRJ supplementation on submaximal exercise oxygen uptake (VO 2 ) and time trial performance (~30 min) in recreationally active females. Methods Using a double‐blind, randomized, crossover design, 12 recreationally active females who were taking oral contraceptives supplemented acutely (2.5 hr) and chronically (8 days) with 280 mL BRJ/day (~26 mmoles NO 3 − ) or the same volume of a nitrate‐free BRJ (PLA). All trials were conducted at the same time in the morning, and there was a 9 ± 0.7 day washout period between trials. Subjects arrived to the laboratory, a baseline blood sample was drawn, a standardized breakfast including 140 mL BRJ or PLA was provided, and a second blood sample was drawn 2 hr later. Blood samples were analyzed for plasma NO 3 − and nitrite (NO 2 − ), as well as estrogen and progesterone. The subjects then cycled for 10 min at 50% and 10 min at 70% VO 2peak , and completed a 4 kJ/kg body mass time trial (TT). Ratings of perceived exertion (RPE), heart rate (HR) and revolutions per minute (rpm) were recorded at 5 min intervals during the submaximal cycling protocol. RPE, HR, rpm, and power output (PO) were recorded as the subjects completed each 20% of the TT. Results There were no significant differences in estrogen or progesterone levels between trials. Plasma NO 3 − concentrations increased significantly following BRJ supplementation compared to PLA (Acute PLA: 44 ± 3 and Chronic PLA, 41 ± 3 μM vs. Acute BRJ, 761 ± 31 and Chronic BRJ, 1091 ± 58 μM). Similarly, plasma NO 2 − increased significantly following BRJ supplementation compared to PLA (Acute PLA, 265 ± 25 and Chronic PLA, 278 ± 26 nM vs. Acute BRJ, 753 ± 84 and Chronic BRJ, 729 ± 101 nM). There was no significant difference in mean VO 2 at 50% VO 2peak (Acute PLA, 1254 ± 45: Acute BRJ, 1259 ± 46: Chronic PLA, 1267 ± 45: Chronic BRJ, 1252 ± 42 mL/min O 2 ) and 70% VO 2peak (Acute PLA, 1804 ± 60: Acute BRJ, 1791 ± 53: Chronic PLA, 1814 ± 54: Chronic BRJ, 1789 ± 54 mL/min O 2 ) between trials. No significant difference was found for rpm, HR, or RPE at 50% or 70% VO 2peak . TT performance was unaffected by BRJ (Acute PLA, 1709 ± 75: Acute BRJ, 1813 ± 97: Chronic PLA, 1751 ± 78: Chronic BRJ, 1791 ± 102 s). No significant difference was found for HR, RPE, or PO between conditions throughout the time trial. Conclusion BRJ did not reduce submaximal exercise oxygen uptake or improve aerobic TT performance in recreationally active females. Future studies should investigate the potential sex differences that may exist with respect to the ergogenic effects of BRJ supplementation. Support or Funding Information Natural Science and Engineering Research Council of Canada (NSERC) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".