Beetroot Juice Increases Skeletal Muscle Force Production in Recreationally Active Subjects.
Bibliographic record
Abstract
Supplementation with dietary inorganic nitrate (NO3-) in the form of beetroot juice (BRJ) reduces whole-body oxygen consumption during submaximal exercise. There are currently two proposed mechanisms to explain this decrease; 1) improved mitochondrial function and 2) improved mechanical efficiency. Previous research has shown that mitochondrial bioenergetics are not improved following 7-d of BRJ supplementation, however there was an increase in H2O2 emission. As reactive oxygen species (ROS) have been shown to increase skeletal muscle (SkM) contractile force, this presents a possible mechanism for the ergogenic effects of BRJ. PURPOSE: To examine the effects of 7-d of BRJ supplementation on SkM contractile characteristics and function. METHODS: Young recreationally active males (n=8) underwent transcutaneous electrical muscle stimulation of the vastus lateralis for evaluation of SkM contractile characteristics pre and post 7-d of BRJ supplementation (280 ml/day, ~26 mmol NO3-). Subjects performed 2 isometric maximal voluntary contractions (MVC), which were used for determination of a voltage that elicited ~40% MVC at 100 Hz. This was subsequently used for performance of a force frequency (FF) curve (10, 20, 30, 50, 100 Hz). Muscle twitches were evoked using a single supramaximal (~150 V, 50 μs duration) impulse twice prior to and twice following performing the FF curve. RESULTS: Following supplementation, there was no change in force produced during MVC (602.1 ± 50.4 vs. 596.6 ± 56.4 N), however peak twitch tension was increased (132.6 ± 3.3 vs. 153.5 ± 6.0 N, p<0.01). While there was no change in twitch half-relaxation time, the maximal rates of force development and relaxation were increased (3529 ± 251 vs. 2455 ± 135 and -2676 ± 283 vs. -2010 ± 168 N/s, respectively, p<0.05). Force was also increased during the FF curve at 10 Hz (41.1 ± 2.3 vs. 37.6 ± 2.4 % of peak force, p<0.05), but was not different at other frequencies. CONCLUSION: Following 7-d of BRJ supplementation, force production at low stimulation frequencies is increased in human SkM. In addition to the increased rates of force development and relaxation, these results suggest a possible mechanism of action for BRJ is via modification of calcium handling or calcium sensitivity of the contractile apparatus, possibly due to ROS. Supported by NSERC, Canada.
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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".