Characterization of performance fatigability during a self-paced exercise
Bibliographic record
Abstract
Pacing during a high-intensity cycling time trial (TT) appears to prevent premature task failure, but the performance fatigability during a self-paced exercise is currently unknown. Therefore, the current study characterized the time course of performance fatigability during a 4-km TT. Eleven male cyclists performed three separated TTs in a crossover, counterbalanced design. The TTs lasted until the end of the fast-start (FS; 600 ± 205 m), even-pace (EP; 3,600 ± 190 m), and end-spurt (ES; 4,000 m) phases. Performance fatigability was characterized by using isometric maximal voluntary contractions (IMVCs), whereas the muscle activation [i.e., voluntary activation (VA)] and contractile function of knee extensors [e.g., peak torque of potentiated twitches (TwPt)] were evaluated using electrically evoked contractions performed before and 1 min after each specific part of the trial. Gas exchange, power output (PO), and electromyographic activity (EMG) were also recorded. EMG/PO showed an abrupt increase followed by a continuous decrease toward the end of FS, resulting in a drop in IMVC (−12%), VA (−8%), and TwPt (−23%). EMG/PO was stable during EP, with no additional drop on IMVC, VA, or TwPt (−12%, −6%, and −22%, respectively). EMG/PO increased abruptly during the ES, but there was no change in IMVCs, VA, or TwPt (−13%, −8%, and −26%, respectively). These findings demonstrate that the performance fatigability during a self-paced exercise is characterized by a large drop in contractile function and muscle activation at the beginning of the trial (i.e., FS), without additional change during the middle and end phases (i.e., EP and ES). NEW & NOTEWORTHY The time course of performance fatigability throughout a self-paced exercise is currently unknown. The results showed that a large amount of muscle activation and contractile function impairments are attained early on a self-paced exercise (first ∼15% of the total time trial distance) and maintained throughout the test. This novel finding characterizes the performance fatigability from a contractile function and muscle activation perspective, which brings new insights for future studies focused on real-world exercise training and competition.
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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".