Residual Force Enhancement Is Attenuated in a Shortening Magnitude-dependent Manner
Bibliographic record
Abstract
INTRODUCTION: The isometric force attained after active stretch is greater than that attained in a purely isometric contraction. This property is referred to as residual force enhancement (RFE). Although RFE is thought to contribute to the enhanced force and power in stretch-shortening cycles (SSCs), it is unclear whether shortening that occurs after active stretch eliminates the RFE induced by active stretch. Therefore, we evaluated the influence of shortening on RFE. METHODS: Skinned rabbit soleus fibers (N = 43) were used for all tests. Residual force enhancement was compared between the stretch-only condition and the SSC condition. In the SSC conditions, shortening magnitudes were either 1% or 12.5% of fiber length. The final muscle length where RFE was evaluated was 3 μm for all trials. In the SSCs with 12.5% shortening, the isometric force before and after the SSC was also compared. RESULTS: Residual force enhancement was similar between the stretch only (7.9% ± 2.7%) and the SSC with 1% shortening condition (7.1% ± 2.9%) (P = 0.316), whereas RFE was smaller in the SSC with 12.5% shortening (3.5% ± 2.4%) than the stretch-only condition (8.4% ± 2.5%) (P < 0.001). The isometric forces after SSCs (0.437 ± 0.103 mN) were greater than those measured before the SSC (0.422 ± 0.104 mN) (P = 0.016). CONCLUSIONS: Residual force enhancement was preserved when the shortening magnitude was small and was reduced when the shortening magnitude was large. Although RFE was attenuated by the 12.5% shortening, RFE was still observed, suggesting that RFE can contribute to SSCs.
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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 | 0.001 |
| 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) | 0.003 | 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".