Upright-to-supine exercise transition in younger and older subjects: effects on pulmonary gas-exchange efficiency
Bibliographic record
Abstract
Background: Supine exercise may improve pulmonary gas exchange efficiency by decreasing apical-basal blood flow gradient and ventilation/perfusion mismatch. Whether this effect is blunted in the elderly remains unclear. Aim: To understand the impact of age on the putative improvement in pulmonary gas-exchange efficiency from upright to supine exercise. Methods: 30 younger (23±3yrs) and 9 older (71±9yrs) subjects with normal pulmonary function completed constant work rate cycle exercise tests in the upright and supine position (same VO2). Ventilatory efficiency (VE/VCO2), KCO, and breath-by-breath volumetric capnography were compared during rest and exercise. Results: Regardless of the body position, older subjects had ↑VE/VCO2, ↑VD/VT, and ↓KCO than younger subjects at rest and during exercise (p<0.05). Older subjects had ↓VE/VCO2 and ↓VD/VT at rest in supine vs. upright. The transition from rest to exercise (Δ) in both positions resulted in similarly ↓VE/VCO2 (Fig A), ↑KCO (C); however, the rest-exercise decline in VD/VT was significant only in younger subjects (B). There were no significant changes in the physiological response to exercise comparing upright to supine in either group (all p>0.05). Conclusions: Senescence is associated with diminished pulmonary gas-exchange efficiency. Supine exercise did not improve “wasted” ventilation compared to upright exercise in older or younger subjects. erj;66/suppl_69/PA6295/F1 F1 F1
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".