A task‐relevant experimental pain model to target motor adaptation
Bibliographic record
Abstract
Key points Motor adaptation is thought to be a strategy to avoid pain. Current experimental pain models do not allow for consistent modulation of pain perception depending on movement. We showed that low‐frequency sinusoidal stimuli delivered at painful intensity result in minimal habituation of pain perception (over 60 s) and minimal stimulation artefacts on electromyographic signals. When the amplitude of the low‐frequency sinusoidal stimuli was modulated based on the vertical force participants applied to the ground with their right leg while standing upright, we demonstrated a strong association between perceived pain and motor adaptation. By enabling task‐relevant modulation of perceived pain intensity and the recording electromyographic signals during electrical painful stimulation, our novel pain model will permit direct experimental testing of the relationship between pain and motor adaptation. Abstract Contemporary pain adaptation theories predict that motor adaptation occurs to limit pain. Current experimental pain models, however, do not allow for pain intensity modulation according to one's posture or movements. We developed a task‐relevant experimental pain model using low‐frequency sinusoidal electrical stimuli applied over the infrapatellar fat pad. In fourteen participants, we compared perceived pain habituation and stimulation‐induced artefacts in vastus medialis electromyographic recordings elicited by sinusoidal (4, 10, 20 and 50 Hz) and square electrical waveforms delivered at constant peak stimulation amplitude. Next, we simulated a clinical condition where perceived knee pain intensity is proportional to the load applied on the leg by controlling sinusoidal current amplitude (4 Hz) according to the vertical force the participants applied with their right leg to the ground while standing upright. Pain ratings habituated over a 60 s period for 50 Hz sinusoidal and square waveforms but not for low‐frequency sinusoidal stimuli (P < 0.001). EMG filters removed most stimulation artefacts for low‐frequency sinusoidal stimuli (4 Hz). While balancing upright, participants’ pain ratings were correlated with the force applied by the right leg (R2 = 0.65), demonstrating task‐relevant changes in perceived pain intensity. Low‐frequency sinusoidal stimuli can induce knee pain of constant intensity for 60 s with minimal EMG artefacts while enabling task‐relevant pain modulation when controlling current amplitude. By enabling task‐dependent modulation of perceived pain intensity, our novel experimental model replicates key temporal aspects of clinical musculoskeletal pain while allowing quantification of neuromuscular activation during painful electrical stimulation. This approach will enable researchers to test the predicted relationship between movement strategies and pain.
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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) | 0.001 | 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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".