Peak Heart Rates at Extreme Altitudes

Lundby, Carsten; Hall, Gerrit van

doi:10.1089/152702901750067909

Cited by 9 publications

(7 citation statements)

References 19 publications

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“…The increase in resting heart rate during exposure to 6022 m and 7042 m, as observed in the present study, corresponds with previous data (Lundby & van Hall, ) and has been attributed mostly to high altitude‐related sympathoexcitation and parasympathetic withdrawal (Siebenmann et al . ).…”

Section: Discussionsupporting

confidence: 93%

Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

Hilty

Merz

Hefti

et al. 2019

The Journal of Physiology

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Key pointsr A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries. r In the present study, we report that high altitude-induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance.r Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude-related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis.r The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success.Abstract A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m Matthias Peter Hilty has found that, during his education and throughout his board certification in General Internal Medicine and Intensive Care Medicine, his main interests lie in the foundations of human physiology, in addition to their application in clinical practice. Studies of the response of the macro-and microcirculation to critical illness and high altitude environments have lead to his high appreciation of the contrast between witnessing cardiovascular pathophysiology during field studies, in laboratory settings and at the bedside. Hoping to support the upcoming challenge to translate these findings to clinical use, Dr Hilty is applying advanced computational techniques for the objective assessment of a patient's microcirculation. M. P. Hilty and othersJ Physiol 597.10 (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVD NG ). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm −2 (P < 0.01). The difference between TVD and TVD NG was 2.28 ± 4.59 mm mm −2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVD NG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVD NG in non-summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingu...

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Section: Discussionsupporting

confidence: 93%

Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

Hilty

Merz

Hefti

et al. 2019

The Journal of Physiology

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“…Extreme altitude climbing has been traditionally studied by scientists and physicians in expeditions [43][44][45][46][47]. The rise in RHR and during exercise starts even at moderate altitudes [48] and returns to sea level values hours after descent.…”

Section: Discussionmentioning

confidence: 99%

“…Other field studies carried out by the "Silver Hut Expedition" certified previously exposed data [12]. In barometric pressure below 530 mmHg (130 m of altitude gained above 3100 m) the maximal HR (MHR) begins to descend in accordance with 1 beat·min -1 for every 7 mmHg [11].…”

Section: Introductionmentioning

confidence: 91%

“…Hypoventilation induces a higher HR both at rest and in exercise, consistently higher in acute HP [9]. At high altitude, HR increases to 136% of the sea level value, but gradually decreases [10], giving a progressive decrement in its peak under conditions of acute HP (6 weeks after acclimatization to 5400 m) [11]. Other field studies carried out by the "Silver Hut Expedition" certified previously exposed data [12].…”

Section: Introductionmentioning

confidence: 99%

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Physiological and Kinanthropometrical Parameters of an Elite Climber. Single case study.

et al. 2012

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“…At lower altitudes peak heart rate remains similar to that observed at sea level, but beyond 4,000 m peak heart rate progressively decreases with increasing altitude, while chronic exposure to hypoxia decreases it even further, because of the increased CaO 2 from the increased haemoglobin. For example, Danish climbers attempting Mt Everest, who prior to departure had mean peak heart rates of 186 bpm in normoxia, and 170 bpm in acute hypoxia (10 % O 2 in N 2 ), after acclimatization at 5,400 m reached peak heart rates of only 155 bpm (Lundby & van Hall, 2001). In that study, in two climbers heart rate was monitored during ascent to 8,750 m (without supplementary O 2 ), with peak rates of only 144 and 148 bpm, respectively.…”

Section: Maximum Heart Rates In Tibetansmentioning

confidence: 99%

Iloprost improves running performance at 5,000 m in Han but not in Tibetans

Kayser

Fan

2019

CISS

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Background: Tibetans experience lose less aerobic exercise capacity in hypoxia compared to lowland Han. We tested if inhalation of iloprost (to counter hypoxic pulmonary vasoconstriction) and furosemide (to decrease afferent vagal traffic from pulmonary receptors) improve performance in hypoxia in Han compared to Tibetans. Methods: 8 Tibetans and 8 Han, living at 2,260 m, did incremental uphill treadmill running to exhaustion at ambient pressure on day 1, followed by three runs at 5,000 m (hypobaric chamber) after inhalation of iloprost (ILO), furosemide (FUR) or placebo (PLA), on different days in a counter-balanced order. Results: In Han the performance decrement from 2,260 m to 5,000 m was greater than in Tibetans (p<0.05). In Han iloprost improved performance at 5,000 m compared to placebo (p<0.05 vs. PLA); furosemide had no effects. In Tibetans there were no treatment effects. Peripheral O2saturations at peak exercise at 5,000 m, were higher by ～8 % in the Tibetans (p<0.05 vs. Han). Maximum heart rate was lowered by 13±6 bpm in Han at 5,000 m regardless of treatment compared to 2,260 m (p<0.05). Tibetans reached similar maximum heart rates ∼200 bpmat 5,000 m and 2,260 m, independent of treatment. Conclusions: The blunting of the exercise impairment in severe hypoxia in Han during maximal exercise after inhalation of iloprost suggests that hypoxic pulmonary vasoconstriction and right ventricular function are potential performance limiting factors in Han in hypoxia.

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Peak Heart Rates at Extreme Altitudes

Cited by 9 publications

References 19 publications

Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m

Physiological and Kinanthropometrical Parameters of an Elite Climber. Single case study.

Iloprost improves running performance at 5,000 m in Han but not in Tibetans

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