Torque and EMG in isometric graded flexion-rotation and extension-rotation
Bibliographic record
Abstract
The main objective of the study was to measure the magnitude and pattern of electromyographic (EMG) activity of the trunk muscles in combined motions of flexion-rotation and extension-rotation. Another objective of the study was to determine the torque-EMG Root Mean Square (RMS) relationship in these activities for predictive purposes. Nineteen normal young adult subjects who met the inclusion criteria were fitted with 12 pairs of surface electrodes on their external and internal oblique, rectus abdominis, latissimus dorsi, and erector spinae muscles at T10 and L3 levels bilaterally. Using a Posture Stabilizing Platform (PSP) they were fixed in 40 degrees flexed and 40 degrees right rotated trunk postures. From this posture subjects attempted an isometric extension-rotation and flexion-rotation in the plane defined by the asymmetrical postural axis in the plane of rotation of the assumed posture. Contractions of 25, 50 and 75% of the previously measured maximal voluntary contraction (MVC) were attempted using a Static Dynamic Strength Tester (SDST) and force monitor attached by a steel cable to a rigid thoracic harness worn by the subjects. The data were acquired at 1 kHz. Descriptive statistics were calculated and ANOVA, correlation and regression analyses were carried out. With linear increase in flexion-rotation and extension-rotation torque, the magnitude of total EMG output increased exponentially. In flexion-rotation the EMG magnitude of all muscles increased with increasing grades of contraction (% of MVC). However, in proportional terms, the magnitude of erector spinae EMG declined. In extension-rotation there was a reversal of roles between the ventral and dorsal muscles compared to the flexion-rotation. For the two genders, all muscles and grades of contractions were significantly different from each other (p<0.01). There was a significant but modest correlation between EMG and torque (r = 0.25 to 0.54; p<0.01). The regressions were significant (p<0.01) and explained up to 74% of the variance in torque. The flexion-rotation and extension-rotation torques can be predicted with only a moderate accuracy.
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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 | 0.001 |
| 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) | 0.003 | 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".