Physiological Adaptation to Altitude: A Comparison of Fast and Slow Ascents to 5,300 m Above Sea Level
Bibliographic record
Abstract
INTRODUCTION: Rapid ascent to altitudes of over 5,000m above sea level are associated with dramatic changes in adaptive physiology. The effects of a gradual ascent on symptoms, oximetry and heart rate are described, and compared with the effects of a rapid ascent to the same altitude by a comparable cohort. METHODS: A group of 13 (6 females) representing 10 countries from 5 continents, ascended gradually from Lukla (2,300m) to Everest Base Camp (5,300m) in Nepal over an 8-day period, then descended over a further 4 days. All symptoms and medication were recorded, along with pulse oximetry and heart rate (HR) every 500m of ascent. The results were then compared with those obtained at equivalent altitudes using similar methodology from a fast ascent of Mount Kilimanjaro to an equivalent altitude by a comparable cohort over 4 days. RESULTS: The gradual ascent group had a median age of 33 years (range 25-66), and all successfully completed the trek. No severe headache, vomiting, orthopnoea nor productive cough occurred, although minor nausea and mild headache was common. Baseline oximetry fell from a median of 96% (93-97%) to a median of 78% (53-86%) at 8 days but recovered to 94% (89-99%) inside 4 days. Corresponding HR rose from a baseline median of 72bpm (57-85) to a median of 103bpm (78-115) at 8 days, then recovered to 80bpm (54-94) after 4 days. Neither age nor gender correlated with outcomes. Individually, HR correlated inversely with oximetry, but there was no group correlation between these two variables. By contrast, a more rapid 4-day ascent from the same starting height, with similar baseline values for HR and oximetry, to the same final altitude was associated with more severe headache, breathlessness, and vomiting. The fast ascent was associated with a more marked reduction in oximetry to a median of 71% (52-76) and an increase in HR to a median of 110bpm (88-140). The fast ascent group also required significantly more medication and rated their experience as less enjoyable. DISCUSSION: Oxygen desaturation and tachycardia are inevitable consequences of ascending above 5,000m but the degree to which this occurs can be reduced by slowing ascent times and taking rest days every 1,000m of ascent. This practice is associated with fewer symptoms and greater safety, with less need for either prophylactic or therapeutic medication. Careful consideration should be given to rates of ascent when climbing to altitudes at or above 5,000m.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".