Physiological characteristics of elite high‐altitude climbers

Abstract

Factors underlying the amplitude of exercise performance reduction at altitude and the development of high-altitude illnesses are not completely understood. To better describe these mechanisms, we assessed cardiorespiratory and tissue oxygenation responses to hypoxia in elite high-altitude climbers. Eleven high-altitude climbers were matched with 11 non-climber trained controls according to gender, age, and fitness level (maximal oxygen consumption, VO2 max ). Subjects performed two maximal incremental cycling tests, in normoxia and in hypoxia (inspiratory oxygen fraction: 0.12). Cardiorespiratory measurements and tissue (cerebral and muscle) oxygenation were assessed continuously. Hypoxic ventilatory and cardiac responses were determined at rest and during exercise; hypercapnic ventilatory response was determined at rest. In hypoxia, climbers exhibited similar reductions to controls in VO2 max (climbers -39 ± 7% vs controls -39 ± 9%), maximal power output (-27 ± 5% vs -26 ± 4%), and arterial oxygen saturation (SpO2 ). However, climbers had lower hypoxic ventilatory response during exercise (1.7 ± 0.5 vs 2.6 ± 0.7 L/min/%; P < 0.05) and lower hypercapnic ventilatory response (1.8 ± 1.4 vs 3.8 ± 2.5 mL/min/mmHg; P < 0.05). Finally, climbers exhibited slower breathing frequency, larger tidal volume and larger muscle oxygenation index. These results suggest that elite climbers show some specific ventilatory and muscular responses to hypoxia possibly because of genetic factors or adaptation to frequent high-altitude climbing.

The human ventilatory response to stress: rate or depth?

“…Bernardi et al (2006) reported that successful high altitude climbers, who could reach the highest summits without oxygen, were characterised by a lower ventilatory sensitivity to hypoxia and a slower ƒ R , compared to those who did not succeed or needed supplemental oxygen. These findings were supported by Puthon et al (2016) who reported that ƒ R was larger in control participants Breathing frequency (% increase from baseline) Tidal Volume (% increase from baseline) compared with elite high-altitude climbers, while V T was larger in climbers compared with controls during maximal incremental cycling tests in both normoxic and hypoxic conditions. Schoene et al (1984) have previously demonstrated that the drop in arterial oxygen saturation that occurs with exercise at altitude is inversely related to HVR, and sojourners with high HVR may perform better at extreme altitude.…”

“…These findings were supported by Puthon et al . () who reported that ƒ R was larger in control participants compared with elite high‐altitude climbers, while V T was larger in climbers compared with controls during maximal incremental cycling tests in both normoxic and hypoxic conditions.…”

“…Increase in tidal volume and respiratory frequency in response to hypoxic exposure Filled triangle represents individuals who required supplementary oxygen and the filled square represents those who did not require supplementary oxygen at altitude (5200 m)(Bernardi et al 2006). Data extracted from the following references:Berssenbrugge et al (1983);Easton & Anthonisen (1988);Georgopoulos et al (1989);Morelli et al (2004);Bernardi et al (2006);Curtis et al (2007);Savourey et al (2007);Faiss et al (2013);Richard et al (2014);Puthon et al (2016).…”

Effect of ageing on hypoxic exercise cardiorespiratory, muscle and cerebral oxygenation responses in healthy humans

“…The hypoxic ventilatory (absolute or relative to body weight) and cardiac responses during the exercise test (at rest, 25%N, 50%N, Exh H and at 90 W) were calculated as follows Puthon et al 2016):…”

“…The hypercapnic ventilatory and cardiac responses during the resting hypercapnic response test were calculated as follows Puthon et al 2016):…”