Bibliographic record
Abstract
Force depression after active shortening has been observed in different muscle preparations. It has been assumed that force depression is caused by the development of sarcomere length nonuniformities after shortening. However, this hypothesis has never been investigated in a preparation where individual sarcomere lengths could be directly measured. Here, we investigated force depression in single myofibrils (n = 11) and tracked simultaneously the changes in individual sarcomere lengths (n = 60) before, during, and after shortening and after a purely isometric contraction performed at the final length. Shortening produced force depression in all myofibrils (mean +/- SE; 30.9 +/- 3.9%). During shortening, all sarcomeres shortened, but not by the same amount. Sarcomere lengths were nonuniform, with the same mean SD before (0.11 +/- 0.06 microm) and after shortening (0.11 +/- 0.06 microm) and after a purely isometric contraction at the final length (0.10 +/- 0.05 microm). Furthermore, greater shortening magnitudes were found for sarcomeres that were long in the initial isometric configuration. Nonuniformities of half-sarcomere lengths were also the same before (SD = 0.13 microm) and after (SD = 0.14 microm) shortening. We conclude from these results that the development of sarcomere (or half-sarcomere) length nonuniformities does not play a major role in force depression. Rather, force depression seems an intrinsic property of individual (half-) sarcomeres and muscle contraction.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".