Why do muscles lose torque potential when activated within their agonistic group?
Bibliographic record
Abstract
Agonistic muscles lose approximately 20% of their individual torque generating capacity when activated with their agonistic muscles compared to when stimulated in isolation. In this study, we (i) tested if this loss in torque was accompanied by a corresponding loss in force, thereby testing the potential role of changes in moment arms between conditions; (ii) removed all inter-muscular connections between the quadriceps muscles, thus determining the potential role of inter-muscular force transmission; and (iii) systematically changed the inter-muscular pressure by performing experiments at different activation/force levels, thereby exploring the possible role of inter-muscular pressure in the loss of torque capacity with simultaneous muscle activation. Experiments were performed in a New Zealand White rabbit quadriceps model (n=5). Torque and force were measured during activation of femoral nerve branches that supply the individual quadriceps muscles while activating these branches simultaneously and in isolation. Regardless of joint angle and inter-muscular connections between muscles, the differences in torque values between the simultaneous and the isolated activation of the quadriceps muscles were also observed for the directly measured force values. Mean differences in simultaneous and isolated muscle activation remained similar between the intact and separated conditions: torque difference (21±5% of maximum isometric torque of intact condition [MICtorque], versus 19±6% MICtorque respectively) and for force (18±3% MICforce versus 19±7% MICforce respectively). The absolute torque loss was independent of the force, and thus presumably the inter-muscular pressures. Based on these results, we conclude that neither moment arm, inter-muscular pressure nor inter-muscular force transmission seems to be the primary cause for the torque deficit observed during simultaneous compared to isolated muscle activation. The mechanisms underlying loss of force capacity during agonistic muscle contraction remain unknown.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".