EFFECT OF MUSCLE CONTRACTION AT VARIOUS PERCENTAGES OF MAXIMAL VOLUNTARY CONTRACTION ON LOCAL BLOOD FLOW VELOCITY
Bibliographic record
Abstract
Purpose It was hypothesized that isometric contraction of skeletal muscles prevents blood from circulating in the contracting muscles, therefore, isolating it from the cardio-pulmonary systems. The purpose of this study was to verify what percentages of isometric maximal voluntary contraction (iMVC) of the forearm are characterized by negligible contribution of central and peripheral circulatory and respiratory systems to muscle function. Method Fifteen healthy individuals (6 women and 9 men; age 27.7 ± 9) were recruited. Comfortably lying on a bed, subjects were asked to perform a standardized isometric hand grip using a hand dynamometer. Subjects were given three trials to perform their iMVC, and the highest score was recorded. Subsequently, the subjects had to maintain, for a minimum of 5 seconds, a tension corresponding to: 20%, 30%, 40%, 50%, 60%, 70% and 80% of the iMVC previously recorded. Two minutes rest was given between each trial and pulsed Doppler echographic measurements were recorded at the radial artery before and during each contraction. Velocity Time Integral (VTI) was later digitally calculated. Results Repeated measure ANOVA demonstrated that the difference between the blood flow at rest and during contractions (Δ VTI), indirectly derived from the VTI analysis, at percentages ≤ 60% of iMVC is statically different from the Δ VTI of iMVC (p < 0.05). This difference could not be explained by the variation of the resting VTI measurements taken initially and before any contraction since they were not statically different from each other (p > 0.44). Compared to resting VTI values, blood flow is reduced by 73% at iMVC and is still reduced by 60% at 60% of iMVC. Conclusion This study confirms that the cardiopulmonary contribution to the skeletal muscle function of the upper extremity is minimal during isometric contraction at or above 60% of iMVC. Further investigation shall be done to confirm if this is also applicable to the lower extremity.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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) | 0.001 | 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".