Experimental pain by ischaemic contractions compared with pain by intramuscular infusions of adenosine and hypertonic saline
Bibliographic record
Abstract
Deep tissue pain can be related to reduced muscle blood flow, which comprises the metabolic demand under muscle work. The tissues and receptors involved in nociception after ischaemic muscle contractions are not known. The concentration of adenosine is increased after ischaemic contractions and might act as an algesic substance. In 15 subjects, adenosine, hypertonic saline (algesic), and isotonic mannitol (placebo) were infused into the tibialis anterior muscle and compared with the pain caused by ischaemic contractions. The muscle pain intensity (visual analogue scale; VAS), distribution, and quality were assessed. Pressure pain thresholds were recorded to assess the deep tissue sensitivity. Adenosine did not induce more pain than the placebo. The maximal VAS score after hypertonic saline and ischaemic contractions was higher compared with adenosine/placebo infusions. The duration and area of pain were significantly increased after hypertonic saline infusions compared with ischaemic contractions. Higher scores on the McGill pain questionnaire were given to the "stabbing", "burning", "heavy", and "exhausting" word categories after ischaemic contractions, and "cramping" was rated higher during hypertonic saline-induced muscle pain compared with ischaemic contractions. During hypertonic saline infusions, the pressure pain threshold was decreased compared with before and immediately after the pain had vanished. The present study shows that pharmacological levels of adenosine in skeletal muscle did not induce pain. Excitation of muscle nociceptors by hypertonic saline evoked hyperalgesia, larger areas of pain, and a different quality of pain compared with ischaemic contractions, suggesting that the pain after ischaemic contractions is mediated by other populations of nociceptors in muscle and/or other tissues than excited by hypertonic saline.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".