Hand temperature responses to local cooling after a 10‐day confinement to normobaric hypoxia with and without exercise

Abstract

The study examined the effects of a 10-day normobaric hypoxic confinement (FiO2: 0.14), with [hypoxic exercise training (HT); n = 8)] or without [hypoxic ambulatory (HA; n = 6)] exercise, on the hand temperature responses during and after local cold stress. Before and after the confinement, subjects immersed their right hand for 30 min in 8 °C water [cold water immersion (CWI)], followed by a 15-min spontaneous rewarming (RW), while breathing either room air (AIR), or a hypoxic gas mixture (HYPO). The hand temperature responses were monitored with thermocouples and infrared thermography. The confinement did not influence the hand temperature responses of the HA group during the AIR and HYPO CWI and the HYPO RW phases; but it impaired the AIR RW response (-1.3 °C; P = 0.05). After the confinement, the hand temperature responses were unaltered in the HT group throughout the AIR trial. However, the average hand temperature was increased during the HYPO CWI (+0.5 °C; P ≤ 0.05) and RW (+2.4 °C; P ≤ 0.001) phases. Accordingly, present findings suggest that prolonged exposure to normobaric hypoxia per se does not alter the hand temperature responses to local cooling; yet, it impairs the normoxic RW response. Conversely, the combined stimuli of continuous hypoxia and exercise enhance the finger cold-induced vasodilatation and hand RW responses, specifically, under hypoxic conditions.

Cold‐induced cutaneous vasoconstriction in humans: Function, dysfunction and the distinctly counterproductive

“…The effects of long-term hypoxia on vasoconstrictor responses to the cold have yielded mixed results, with some studies showing an improved or partly restored vascular response (Daanen & van Ruiten, 2000;Felicijan, Golja, Milcinski, Cheung, & Mekjavic, 2008) and others showing no change (Keramidas, Kolegard, Mekjavic, & Eiken, 2015) or an impaired vascular response (Kounalakis, Keramidas, Amon, Eiken, & Mekjavic, 2017;Savourey et al, 1997) after acclimation to hypoxia. The effects of long-term hypoxia on vasoconstrictor responses to the cold have yielded mixed results, with some studies showing an improved or partly restored vascular response (Daanen & van Ruiten, 2000;Felicijan, Golja, Milcinski, Cheung, & Mekjavic, 2008) and others showing no change (Keramidas, Kolegard, Mekjavic, & Eiken, 2015) or an impaired vascular response (Kounalakis, Keramidas, Amon, Eiken, & Mekjavic, 2017;Savourey et al, 1997) after acclimation to hypoxia.…”

“…The aforementioned studies have described thermoregulatory responses to acute hypoxic exposure. The effects of long-term hypoxia on vasoconstrictor responses to the cold have yielded mixed results, with some studies showing an improved or partly restored vascular response (Daanen & van Ruiten, 2000;Felicijan, Golja, Milcinski, Cheung, & Mekjavic, 2008) and others showing no change (Keramidas, Kolegard, Mekjavic, & Eiken, 2015) or an impaired vascular response (Kounalakis, Keramidas, Amon, Eiken, & Mekjavic, 2017;Savourey et al, 1997) after acclimation to hypoxia. Further studies that examine vasoconstrictor responses to cold stress after long-term hypoxic exposure are warranted.…”

Effect of exercise on night periodic breathing and loop gain during hypoxic confinement

“…The environmental conditions of the confinement area were: 23 ± 1°C, 57 ± 8% relative humidity, 682 ± 4 mm Hg barometric pressure. Hypoxia was maintained using a vacuum pressure swing adsorption system (b‐Cat, Tiel, The Netherlands), described elsewhere . The hypoxic system maintained a fraction of oxygen of 0.139 ± 0.003 (F I O 2 ).…”

“…Hypoxia was maintained using a vacuum pressure swing adsorption system (b-Cat, Tiel, The Netherlands), described elsewhere. 20,22 The hypoxic system maintained a fraction of oxygen of 0.139 ± 0.003 (FIO2). Accounting for the daily fluctuations in barometric pressure, the partial pressure of inspired oxygen (PIO2) was 88.2 ± 0.6 mm Hg, corresponding to an equivalent altitude of 4175 m.…”

Single-digit cold-induced vasodilation adaptations during an Antarctic expedition

“…Unlike in the Arctic, during Antarctic expeditions, humans face both extreme cold and altitude (mean annual ambient temperature: approximately − 50 °C; mean elevation: approximately 2500 m); however, until recently, the cold-induced adaptations made to these combined stressors had not been investigated (Keramidas et al 2018). Acute exposure to altitude (3500 m) can transiently reduce the CIVD response in lowland natives (Mathew et al 1977;Daanen and van Ruiten 2000); however, normobaric hypoxia has no effect unless coupled with regular exercise (Keramidas et al 2015) and hypobaric hypoxia has no effect in normal ambient temperatures (O'Brien et al 2015). Whilst the data regarding the effects of acute altitude exposure of CIVD responses are equivocal, responses can be improved following long-term exposure.…”