Exercise Performance of Lowlanders with COPD at 2,590 m: Data from a Randomized Trial
Why this work is in the frame
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Bibliographic record
Abstract
<b><i>Background:</i></b> Effects of hypobaric hypoxia at altitude on exercise performance of lowlanders with chronic obstructive pulmonary disease (COPD) have not been studied in detail. <b><i>Objectives:</i></b> To quantify changes in exercise performance and associated physiologic responses in lowlanders with COPD travelling to moderate altitude. <b><i>Methods:</i></b> A total of 31 COPD patients with a median age (quartiles) of 66 years (59; 69) and FEV<sub>1</sub> of 56% predicted (49; 69) living below 800 m performed a constant-load bicycle exercise to exhaustion at 60% of the maximal work rate at 490 m (Zurich) and at an identical work rate at 2,590 m (Davos) in randomized order. Pulmonary gas exchange, pulse oximetry (SpO<sub>2</sub>), cerebral tissue oxygenation (CTO; near-infrared spectroscopy), and middle cerebral artery peak blood flow velocity (MCAv) by Doppler ultrasound during 30 s at end exercise were compared between altitudes. <b><i>Results:</i></b> With ascent from 490 to 2,590 m, the median endurance time (quartiles) was reduced from 500 s (256; 795) to 205 s (139; 297) by a median (95% CI) of 303 s (150–420) (<i>p</i> &#x3c; 0.001). End exercise SpO<sub>2</sub> decreased from 92% (89; 94) to 81% (77; 84) and CTO from 62% (56; 66) to 55% (50; 60); end exercise minute ventilation increased from 40.6 L/min (35.5; 47.8) to 47.2 L/min (39.6; 58.7) (<i>p</i> &#x3c; 0.05; all comparisons 2,590 vs. 490 m). MCAv increased similarly from rest to end exercise at 490 m (+25% [17; 36]) and at 2,590 m (+21% [14; 30]). However, the ratio of MCAv increase to SpO<sub>2</sub> drop during exercise decreased from +6%/% (3; 12) at 490 m to +3%/% (2; 5) at 2,590 m (<i>p</i> &#x3c; 0.05). <b><i>Conclusions:</i></b> In lowlanders with COPD travelling to 2,590 m, exercise endurance is reduced by more than half compared to 490 m in association with reductions in systemic and cerebral oxygen availability.
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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 | 0.000 | 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 it