Group Of Climbers Research Articles

Effect of altitude on body composition during mountaineering expeditions: interrelationships with changes in dietary habits.

Loss of body weight occurs during high mountain expeditions but whether it is due to inadequate diet or other factors is unknown. Moreover the composition of the weight loss is unclear. The aim of our study was to compare the nutritional, anthropometric and metabolic changes during a mountaineering expedition in two groups of climbers, whose dietary energy intake was ad libitum, one given a lacto-fish-ovo-vegetarian diet and one an omnivorous diet. The intake of various nutrients, body weight, body composition and metabolic variables were evaluated before and during high altitude exposure and after the return to low altitude. The two groups were matched for age, body mass index and gender. No significant differences were found for nutritional variables between the two groups. Energy, animal and vegetable protein and fiber intake were significantly lower at climbing quote than before the beginning of the expedition. Significant differences between before the beginning and base camp in all variables were found. Energy and animal protein intake, but not vegetable protein and fiber intake, were significantly lower at climbing quote than at base camp. All subjects significantly reduced body weight, body mass index, waist and hip circumferences but not fat-free mass and fat mass. Metabolic variables significantly improved after the mountaineering expedition. Our study seems to confirm that a mountaineering expedition decreases energy and protein intake, reduces body weight and improves metabolic variables. Because our subjects spontaneously tended to have the same food intake despite the different dietary recommendations, our study failed to observe any differences between the two groups. However, our study shows that a low protein diet, in which the type of protein is mostly vegetable protein, could be adapted for climbers determining only a small decrease of fat-free mass.

Effects of exposure to low oxygen pressure on the central nervous system.

During the past few years high altitude climbing without supplementary oxygen has become one of the most fascinating adventures for an increasingly large number of mountaineers, since an elite group of climbers conquered all 14 of the 8000m peaks in the world. It is widely recognised that acute exposure to low oxygen pressure may cause neurological problems such as movement disorders, incoordination, neuropsychological defects and visual impairment (McFarland 1937; Sharma et al. 1975; Sharma & Malhotra 1976). However, only recently has the possibility been raised that persistent neurological impairment may ensue after high altitude climbing without supplementary oxygen (Cavaletti et al. 1987, 1990; Kassirer & Von Pelejo Such 1989; Regard et al. 1989; Ryn 1971; Townes et al. 1984; West 1986). In this review we consider the physiological changes induced by hypoxia on the human pulmonary, cardiovascular and haemopoietic systems and its acute and chronic effects on the central nervous system (CNS).

Muscle structure and performance capacity of Himalayan Sherpas

The ultrastructure of the vastus lateralis muscle of Sherpas from Nepal [5 males; age 28 +/- 2.8 (SD) yr, indirect maximal O2 consumption 48.5 +/- 5.4 ml.kg(-1).min(-1)] was assessed and compared with those of sedentary lowlanders and of Caucasian climbers before and after high-altitude exposure. The mean cross-sectional area of the fibers was 3,186 +/- 521 microns2, i.e., similar to those of Caucasian elite high-altitude climbers (3,108 +/- 303 microns2) and a group of climbers after a 6- to 8-wk sojourn at 5,000-8,600 m (3,360 +/- 580 microns2) but significantly (P less than 0.05) smaller than that of unacclimatized climbers (4,170 +/- 710 microns2) and slightly, although not significantly, lower than that of sedentary lowlanders (3,640 +/- 260 microns2). The number of capillaries per square millimeter of muscle cross section was 467 +/- 22, not significantly smaller than those of climbers on return from a Himalayan expedition (538 +/- 89) and elite high-altitude climbers (542 +/- 127) but significantly (P less than 0.05) greater than that of sedentary lowlanders (387 +/- 25). The volume density of mitochondria was 3.96 +/- 0.54%, significantly (P less than 0.05) less than the values found for any other investigated group, including sedentary subjects at sea level (4.74 +/- 0.30%). It is concluded that Sherpas, like acclimatized Caucasian climbers, are characterized by 1) facilitated convective and diffusive muscle O2 flow conditions and 2) a higher maximal O2 consumption-to-mitochondrial volume ratio than lowlanders despite a reduced mitochondrial volume density.

Relationship of hypoxic ventilatory response to exercise performance on Mount Everest.

At very high altitude, exercise performance in the human sojourner may depend on a sufficient hypoxic ventilatory response (HVR). To study the relationship of HVR to exercise performance at high altitude, we studied HVR at sea level and 5,400 m and exercise ventilation at sea level, 5,400 m, and 6,300 m in nine members of the American Medical Research Expedition to Everest. The relationship of HVR between individuals was maintained when HVR was repeated after acclimatization to 5,400 m (P less than 0.05). There was a significant correlation in all subjects between HVR and ventilatory equivalent during exercise at sea level (r = 0.704, P less than 0.05). Subjects were then grouped into high (H) and low (L) HVR responders (ventilation increase to end-tidal PO2 of 40 Torr = 21.2 +/- 5.4 and 5.6 +/- 0.9 1 X min-1, respectively. At low and moderate levels of exercise, ventilation at sea level and after acclimatization to 6,300 m was higher in the high HVR group. At 6,300 m blood O2 saturation (Sao2%) decreased from rest to maximum exercise: H = 8.3 +/- 1.8%, L = 20.0 +/- 2.5% (P less than 0.01). HVR correlated inversely in all subjects with the decrease in Sao2 from rest to maximum exercise (P less than 0.05). Climbers with the highest HVR values reached and slept at higher altitudes. We conclude that the relative value of HVR in our group of climbers was not significantly altered after acclimatization; HVR predicts exercise ventilation at sea level and high altitude; the drop in Sao2% that occurs with exercise is inversely related to HVR; and sojourners with high HVR may perform better at extreme altitude.