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The ups and downs of high altitude mountaineering
  1. Damian Miles Bailey
  1. Senior Lecturer in Physiology, 1998 Mt Kanchenjunga Medical Expedition, c/o Hypoxia Research Unit, Health and Exercise Sciences Research Laboratory, University of Glamorgan, Pontypridd CF37 1DL, UK

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    Editor,—Professor Craig Sharp delighted us with a recent account of his world record ascent of Mt Kilimanjaro in the 1960s and voiced his concerns about the physiological dangers inherent in such a feat;1 the madness and exuberance of youth! It is interesting to note that this record was established during the height of one of the most unforgettable debates in mountaineering history provoked by the initial uncertainties of Barcroft, Margaria, and Henderson, the possibility of an “oxygenless” ascent of Mt Everest. The epochal ascent without supplemental oxygen by Messner in 1978 subsequently put paid to any speculation and reinforced what T H Huxley (1825–1895) once remarked “The great tragedy of science; the slaying of a beautiful hypothesis by an ugly fact!”

    The “get up and get down” philosophy of mountaineering has become an increasingly popular practice among enthusiasts who are either pitting their physical attributes against the stopwatch or, as Messner would maintain, merely limiting their time spent in the “death zone”. Perhaps the most astonishing feat of all was achieved during an Italian expedition to Mt Everest in May 1996 when Hans Kammerlander summited via the North Col in a record time of 17 hours and then descended to basecamp on skiis! However, although extending the envelope of human endurance, the risks inherent in such an extreme sport simply cannot be ignored.

    For example, research in our laboratory has recently indicated a pronounced increase in metabolic biomarkers of free radical and skeletal muscle damage at 5100 m due primarily to the oxidative and reductive stress imposed by physical exercise and environmental hypoxia respectively. We have also incriminated free radicals in the pathophysiology of acute mountain sickness and endothelial dysfunction at high altitude.2 Thus, when one considers the average hourly ascent rates by Sharp and Kammerlander of about 611 m and about 215 m respectively compared with the more leisurely 12–30 m typically encountered during a Himalayan expedition, the potential for suffering at the hands (or more appropriately electrons!) of these ubiquitous biomolecules is all too apparent. Free radical generation may be further compounded during a rapid as opposed to a steady controlled descent because of the mechanical trauma of eccentric muscle contractions and greater increase in arterial pO2 implicit in reoxygenation injury.

    But how do these mountaineers achieve such remarkable feats and survive to tell the tale when others falter even at the slightest whiff of hypoxia? The fact that Professor Sharp was effectively a native highlander at the time of his record suggests that acclimatisation may have conferred at least some protection. Or perhaps he is one of the genetically gifted with the I allele of the ACE gene recently associated with improved performance at high altitude?3 While this remains a riddle wrapped in a mystery inside an enigma, it would seem wise counselling to ensure that those antioxidants are packed before visiting one of nature's wonders!

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