Speeding of V<scp>o</scp><sub>2</sub> kinetics with endurance training in old and young men is associated with improved matching of local O<sub>2</sub> delivery to muscle O<sub>2</sub> utilization
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Bibliographic record
Abstract
The time course and mechanisms of adjustment of pulmonary oxygen uptake (V(O(2))) kinetics (time constant tauV(O(2p))) were examined during step transitions from 20 W to moderate-intensity cycling in eight older men (O; 68 +/- 7 yr) and eight young men (Y; 23 +/- 5 yr) before training and at 3, 6, 9, and 12 wk of endurance training. V(O(2p)) was measured breath by breath with a volume turbine and a mass spectrometer. Changes in deoxygenated hemoglobin concentration (Delta[HHb]) were measured by near-infrared spectroscopy. V(O(2p)) and Delta[HHb] were modeled with a monoexponential model. Training was performed on a cycle ergometer three times per week for 45 min at approximately 70% of peak V(O(2)). Pretraining tauV(O(2p)) was greater (P < 0.05) in O (43 +/- 10 s) than Y (34 +/- 8 s). tauV(O(2p)) decreased (P < 0.05) by 3 wk of training in both O (35 +/- 9 s) and Y (22 +/- 8 s), with no further changes thereafter. The pretraining overall adjustment of Delta[HHb] was faster than tauV(O(2p)) in both O and Y, resulting in Delta[HHb]/V(O(2p)) displaying an "overshoot" during the transient relative to the subsequent steady-state level. After 3 wk of training the Delta[HHb]/V(O(2p)) overshoot was attenuated in both O and Y. With further training, this overshoot persisted in O but was eliminated after 6 wk in Y. The training-induced speeding of V(O(2p)) kinetics in O and Y at 3 wk of training was associated with an improved matching of local O(2) delivery to muscle V(O(2)) (as represented by a lower Delta[HHb]/V(O(2p))). The continued overshoot in Delta[HHb]/V(O(2p)) in O may reflect a reduced vasodilatory responsiveness that may limit muscle blood flow distribution during the on-transient of exercise.
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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) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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