The plateau in the NIRS-derived [HHb] signal near the end of a ramp incremental test does not indicate the upper limit of O<sub>2</sub> extraction in the vastus lateralis
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Bibliographic record
Abstract
This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O 2 ) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O 2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg, 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O 2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBF OCC1 ) and immediately after the RI test (LBF OCC2 ). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBF OCC1 ) and the peak values during exercise (100 ± 0%; [HHb] plateau ) were significantly greater than those observed at baseline (0.84 ± 10.6% at baseline 1 and 0 ± 0% at baseline 2) ( P < 0.05). No significant difference was found between LBF OCC1 and [HHb] plateau ( P > 0.05) or between the baseline measurements ( P > 0.05). [HHb] values at LBF OCC2 (130.5 ± 19.7%) were significantly greater than all other time points ( P < 0.05). These results support the existence of an O 2 extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O 2 extraction.
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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 | 0.001 | 0.006 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 it