Load Dependent Modifications To Stimulated Concentric Torque-frequency And Angular Velocity-frequency Relationships In Human Knee Extensors
Bibliographic record
Abstract
PURPOSE: To compare electrically stimulated concentric torque-frequency and angular velocity-frequency relationships during isotonic contractions at two loads. METHODS: In a Cybex dynamometer the right knee extensors of 10 healthy young (26 ± 4 years) adults were tested. Stimulating electrodes were placed transversely over proximal and distal portions of the knee extensors. Electrical current level was set to produce 50% isometric maximal voluntary contraction (MVC) torque at 100 Hz. In the “isotonic mode” dynamic contractions were stimulated through a range of motion from 90 - 150°. With the dynamometer load set to 0% and 15% MVC, contractions were stimulated in ascending frequency at 1, 5, 7.5, 10, 12, 15, 17, 20, 25, 30, 40, 50, 75 and 100 Hz, with 20s of rest between contractions. Stimulation pulses ceased once full range of motion was achieved or when full range of motion was unachievable. RESULTS: Data are presented as a percentage of relative peak concentric torque or peak velocity for 100 Hz. For unloaded isotonic contractions, at 1 and 5 Hz velocity was ~58 and ~ 24 % lower than torque (both p < 0.003), with no difference at 7.5 Hz (p = 0.8). From 10 - 30 Hz velocity was 5 - 13 % greater than concentric torque (p = 0.0006 - 0.04). At 40 - 100 Hz there were no statistical differences ranging from 0 - 3%. During loaded isotonic contractions, frequencies up to 7.5 Hz did not produce enough torque to generate joint rotation and thus velocity was 0%. From 10 - 15 Hz peak velocity was 35-95% lower than torque (all p < 0.001). From 17 - 40 Hz velocity was 5 - 35% lower than torque (all p < 0.05). From 50 - 100 Hz differences were not statistically different (0 - 3%). CONCLUSIONS: During unloaded isotonic contractions stimulated at 10-30 Hz, the angular velocity-frequency relationship was shifted leftward relative to the concentric torque-frequency relationship. Conversely, during a moderately loaded isotonic contraction stimulated at 10 - 40 Hz, the angular velocity-frequency relationship was rightward shifted relative to the concentric torque-frequency relationship. Thus, altering the load during an isotonic contraction modifies both the angular velocity- and concentric torque-frequency relationships at moderate stimulation frequencies. Supported by NSERC.
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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) | 0.002 | 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".