RATE OF FORCE RELAXATION FOLLOWING ENHANCEMENT
Bibliographic record
Abstract
The enhancement of isometric force following active stretch is a well accepted characteristic of skeletal muscle that has been demonstrated in both whole tissue [1,2] and single fiber [1,3] preparations. However, the underlying mechanism of force enhancement remains unkown. PURPOSE We investigated the force relaxation (decrease of enhanced isometric tension following stretch), and its dependence on both the amount and velocity of stretching, in an attempt to elucidate the underlying mechanisms of force enhancement. METHODS A post hoc analysis was conducted on previously described force enhancement experiments [2] on the descending limb of in situ cat soleus muscles (N=8). In these experiments stretch amount (3,6,9mm) and velocity (3,9,27mm•S−1) were systematically varied. The 4.5-second isometric tension following stretch was analyzed, in which the tissue was held at the final length while tetanically stimulated (3T). The force relaxation was fit with excellent agreement using a logarithmic function (F = A•ln(t)+Fo), were A represents the rate of relaxation. RESULTS Using a complete block design ANOVA, the rate of force relaxation displayed a direct dependence on stretch amplitude (p < 0.05), a significant dependence on stretch velocity (p < 0.05), and no amplitude-velocity interaction (p < 0.2). CONCLUSIONS The relaxation rate of force-enhanced cat soleus muscle increased (faster relaxation) with stretch amplitude, and decreased from the two slower velocities to the fastest (27 mm•S−1), (p < 0.05, each). Likewise, prior analysis indicated the magnitude of force-enhancement increased with stretch amplitude [2]. Thus, the relaxation rate increases with increasing enhancement. These findings support a proposed mechanism by which the force is enhanced, in part, by a passive structural element. An increase in passive stiffness could both enhance the tissue's isometric force at a given length, and increase the rate of force relaxation. REFERENCES [1]Edman et al. (1978) J. Physiol. (London). [2]Herzog and Leonard (2002) J. Exp. Biol., [3]Sugi and Tsuchiya (1988) J. Physiol. (London). Supported by Alberta Ingenuity Fund
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".