Prior exercise speeds pulmonary O<sub>2</sub> uptake kinetics by increases in both local muscle O<sub>2</sub> availability and O<sub>2</sub> utilization
Bibliographic record
Abstract
The effect of prior exercise on pulmonary O(2) uptake (Vo(2)(p)), leg blood flow (LBF), and muscle deoxygenation at the onset of heavy-intensity alternate-leg knee-extension (KE) exercise was examined. Seven subjects [27 (5) yr; mean (SD)] performed step transitions (n = 3; 8 min) from passive KE following no warm-up (HVY 1) and heavy-intensity (Delta50%, 8 min; HVY 2) KE exercise. Vo(2)(p) was measured breath-by-breath; LBF was measured by Doppler ultrasound at the femoral artery; and oxy (O(2)Hb)-, deoxy (HHb)-, and total (Hb(tot)) hemoglobin/myoglobin of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). Phase 2 Vo(2)(p), LBF, and HHb data were fit with a monoexponential model. The time delay (TD) from exercise onset to an increase in HHb was also determined and an HHb effective time constant (HHb - MRT = TD + tau) was calculated. Prior heavy-intensity exercise resulted in a speeding (P < 0.05) of phase 2 Vo(2)(p) kinetics [HVY 1: 42 s (6); HVY 2: 37 s (8)], with no change in the phase 2 amplitude [HVY 1: 1.43 l/min (0.21); HVY 2: 1.48 l/min (0.21)] or amplitude of the Vo(2)(p) slow component [HVY 1: 0.18 l/min (0.08); HVY 2: 0.18 l/min (0.09)]. O(2)Hb and Hb(tot) were elevated throughout the on-transient following prior heavy-intensity exercise. The tauLBF [HVY 1: 39 s (7); HVY 2: 47 s (21); P = 0.48] and HHb-MRT [HVY 1: 23 s (4); HVY 2: 21 s (7); P = 0.63] were unaffected by prior exercise. However, the increase in HHb [HVY 1: 21 microM (10); HVY 2: 25 microM (10); P < 0.001] and the HHb-to-Vo(2)(p) ratio [(HHb/Vo(2)(p)) HVY 1: 14 microM x l(-1) x min(-1) (6); HVY 2: 17 microM x l(-1) x min(-1) (5); P < 0.05] were greater following prior heavy-intensity exercise. These results suggest that the speeding of phase 2 tauVo(2)(p) was the result of both elevated local O(2) availability and greater O(2) extraction evidenced by the greater HHb amplitude and HHb/Vo(2)(p) ratio following prior heavy-intensity exercise.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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 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".