Serial sarcomerogenesis does not contribute to the initial repeated bout effect in skeletal muscle
Bibliographic record
Abstract
Neuromuscular function is impaired following an unaccustomed bout of eccentric exercise. However, through the repeated bout effect (RBE), the muscle is protected from impaired neuromuscular function following a subsequent bout of eccentric exercise. It has been speculated that the addition of sarcomeres in series (sarcomerogenesis) contributes to the RBE by reducing mechanical strain on muscle fibers during active lengthening. However, whether sarcomerogenesis actually contributes to the RBE is unknown. We investigated whether a single bout of damaging eccentric exercise induces serial sarcomerogenesis, and if this offers a protective effect on the muscle. Using an in-vivo set up, twenty-four Sprague-Dawley rats performed maximal eccentric contractions of the plantar flexors to impair mechanical function. Thirteen days following the initial eccentric exercise bout, twelve rats were sacrificed, to assess serial sarcomere number (SSN) of the soleus and medial gastrocnemius (MG) via laser diffraction. The remaining twelve rats completed an identical second bout of eccentric exercise to assess the RBE. A single bout caused long lasting impairments in torque production (-3% for 100 Hz; -16 % for 10 Hz; P < 0.05 compared to baseline). Following the repeated bout, there was a protective effect with all torque measures recovering by 2 days post-exercise (P > 0.05 compared to baseline). SSN did not differ between the control and exercised legs for either muscle (P > 0.05). There was a robust RBE following the second bout of eccentric exercise, with no increase in SSN indicating serial sarcomerogenesis is not one of the primary initial mechanisms contributing to the RBE.
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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 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".