Effects of acute isometric knee extension exercise at 40% MVC on muscle mechanical properties and Ca2+ pump function
Bibliographic record
Abstract
To investigate the effects of intermittent isometric knee extension exercise on muscle mechanical properties and sarcoplasmic reticulum (SR) Ca2+‐ATPase activity, 8 healthy males performed 30 minutes of single‐legged knee extension exercise at 40% maximal voluntary contraction (MVC) with a 50% duty cycle (5 sec. contraction, 5 sec relaxation). Quadriceps isometric contractile properties were measured during voluntary and evoked contractions before (PRE) and after (POST) exercise and on recovery day 1 (R1), 2 (R2), 3 (R3) and 6 (R6). Exercise caused a reduction (p<0.05) in the maximal twitch force POST when compared with PRE (141 ± 15 vs. 74 ± 8, N) that had recovered by R1 (135 ± 11, N). MVC force was also depressed (p<0.05) POST when compared to PRE (557 ± 58 vs. 313 ± 16), but unlike evoked force, did not fully recover until R6 (p<0.05).Measurements of maximal Ca2+‐ATPase activity (uM/mg protein/min) were made in homogenates that were prepared from muscle biopsy samples taken before and after exercise and throughout recovery. Compared with PRE, maximal Ca2+‐ATPase activity was not different at any time point. In conclusion, muscle fatigue caused by intermittent isometric knee extension exercise at 40% MVC is not associated with intrinsic alterations in SR Ca2+‐ATPase function in humans. Supported by NSERC
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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 | 0.001 | 0.000 |
| 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 | 0.000 | 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".