Evoked Contractile Properties of the Quadriceps Across a Clinical Spectrum of Knee Osteoarthritis
Bibliographic record
Abstract
Evoked contractile properties of whole muscle can provide indirect information about fibre composition and may provide insight into the mechanisms of quadriceps muscle weakness in knee osteoarthritis (OA). PURPOSE: To determine if differences in evoked contractile properties exist across a clinical spectrum of knee OA. METHODS: The following parameters were measured in the knee extensors in thirty-four patients (19 female) with clinical or radiographic knee OA: 1) isometric maximal voluntary torque, 2) resting maximal twitch tension (PT), time-to-peak tension (TPT) and half-relaxation time (HRT), 3) force-frequency characteristics measured with 500 ms pulse trains of 1, 2, 5, 8, 10, 12, 15, 20, 30, 40, 50, 75 and 100 Hz, with stimulus intensity normalized to a value eliciting a torque equivalent to 20% maximal voluntary contraction at 100 Hz. In order to facilitate comparison, participants were stratified into tertiles of disease severity based on their responses to the Western Ontario and McMaster Osteoarthritis Index. The lowest, middle and highest tertiles were designated mild, moderate and severe knee OA, respectively. RESULTS: Maximal isometric strength (normalized to body mass) was significantly lower in the severe (∼45%) and moderate (∼30%) compared to mild subgroup with post-hoc testing (p<0.05). No significant differences were observed across groups for PT, TPT or HRT (p>0.05). Torque values for each subgroup were not significantly different at any of the stimulation frequencies (p>0.05). CONCLUSION: Evoked contractile properties of quadriceps were not different across a clinical spectrum of patients with knee OA, despite differences in isometric knee extensor strength. These results indicate that muscle fibre composition may not be altered in knee OA and other mechanisms may play a greater role in the observed strength losses.
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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) | 0.001 | 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".