Circadian rhythm of peripheral perfusion during 10-day hypoxic confinement and bed rest

McDonnell, Adam C.; Eiken, Ola; Mekjavič, Polona Jaki; Mekjavić, Igor B.

doi:10.1007/s00421-014-2923-9

Cited by 22 publications

(19 citation statements)

References 32 publications

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“…observed a progressive decrease in subjects' skin temperature during 35 days of horizontal bedrest, with changes particularly obvious in distal body regions, and with the most pronounced temperature decrements observed at the tips of the toes, suggesting that cutaneous vasomotor tone increased gradually during the course of the bedrest. During sustained hypoxic exposure, cutaneous vasoconstriction was shown to increase from day 1 to day 10, especially in lower extremities (McDonnell et al, 2014). Yogev et al (2010), on the other hand, observed no significant difference in ΔT forearm-fingertip and ΔT calf-toe between days 1 and 22 of bedrest, a finding which is in agreement with the observations in the present study when comparing days 10 and 20 with baseline values within all three experimental conditions.…”

Section: Body Temperature and Proximal-to-distal Skin Temperature Grasupporting

confidence: 94%

“…The subjects in our study did not wear socks during the experiment, and could hence have been experiencing regional discomfort by feeling cold during the course of the one-hour trial, especially due to exaggerated cutaneous vasoconstriction, induced by prolonged hypoxia and/or bedrest McDonnell et al, 2014). It is therefore conceivable that, in all three conditions, they could have regulated T wps at a higher level than in a normoxic ambulatory condition to outbalance the discomfort associated with cold feet.…”

Section: Thermal Comfort Ratingmentioning

confidence: 83%

“…Hypoxia has also been reported to alter autonomic thermoregulatory responses, such as cutaneous vasoconstriction McDonnell et al, 2014), and to decrease sensitivity to cold (Golja et al, 2004), hence potentially changing the perception of thermal comfort. It has been suggested that a normobaric hypoxic exposure induces slowing of neural activity in the sensor-to-effector pathway, but does not affect the threshold for cutaneous detection of either warmth or cold (Malanda et al, 2008).…”

Section: The Combined and Separate Effect Of Inactivity/unloading Andmentioning

confidence: 99%

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Effects of normobaric hypoxic bed rest on the thermal comfort zone

Ciuha

Eiken

Mekjavic

2015

Journal of Thermal Biology

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Section: Body Temperature and Proximal-to-distal Skin Temperature Grasupporting

confidence: 94%

Section: Thermal Comfort Ratingmentioning

confidence: 83%

Section: The Combined and Separate Effect Of Inactivity/unloading Andmentioning

confidence: 99%

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Effects of normobaric hypoxic bed rest on the thermal comfort zone

Ciuha

Eiken

Mekjavic

2015

Journal of Thermal Biology

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“…The study was part of the 'LunHab: Lunar Habitat Simulation' project investigating the effects of a 10 day hypoxic bedrest on several functions of cardiorespiratory and musculoskeletal systems (see Debevec et al 2014;McDonnell et al 2014;Salvadego et al 2016). The study was part of the 'LunHab: Lunar Habitat Simulation' project investigating the effects of a 10 day hypoxic bedrest on several functions of cardiorespiratory and musculoskeletal systems (see Debevec et al 2014;McDonnell et al 2014;Salvadego et al 2016).…”

Section: Ethical Approvalmentioning

confidence: 99%

LunHab: interactive effects of a 10 day sustained exposure to hypoxia and bedrest on aerobic exercise capacity in male lowlanders

Keramidas

Mekjavic

Eiken

2017

Experimental Physiology

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What is the central question of this study? What are the distinct and interactive effects of a 10 day exposure to hypoxia and horizontal bedrest on the whole-body peak oxygen uptake and on the regional cerebral and skeletal muscle tissue oxygenation during upright cycle ergometry in male lowlanders? What is the main finding and its importance? A 10 day sustained exposure to hypoxia aggravates the bedrest-induced reduction in peak oxygen uptake during dynamic exercise engaging large muscle groups, but mitigates the skeletal muscle oxidative capacity impairment elicited by bedrest. The study examined the interactive effects of a 10 day exposure to hypoxia and bedrest on the whole-body peak oxygen uptake (V̇O2 peak ) during maximal exercise and on skeletal muscle and cerebral oxygenation during submaximal exercise. Nine males underwent three 10 day confinements, in a Latin-square order, as follows: (i) a normoxic bedrest [NBR; partial pressure of inspired O (PI,O2) = 134.2 ± 0.7 mmHg]; (ii) a hypoxic bedrest (HBR; PI,O2 = 102.9 ± 0.1 mmHg at day 1, 91.5 ± 1.2 mmHg at days 3-10); and (iii) a hypoxic ambulation (HAMB; PI,O2 as in HBR). Before, 1 (R+1) and 3 days (R+3) after each confinement, subjects performed exhaustive, incremental-load and moderate-intensity constant-load (CLTs) cycle-ergometry trials, while breathing either room air or a hypoxic gas mixture. During the CLTs, changes in the regional oxygenation of the cerebral frontal cortex and the vastus lateralis and intercostal muscles were monitored with near-infrared spectroscopy. At R+1, the confinement-related impairment in V̇O2 peak was greater after HBR than after NBR or HAMB, regardless of whether the trial was performed in room air or hypoxia (HBR, -16.2%; NBR, -8.3%; HAMB, -4.1%; P = 0.001). During the CLTs, bedrest aggravated the exercise-induced reduction in locomotor and respiratory muscle oxygenation (P ≤ 0.05); an effect that was less after HBR than after NBR (P ≤ 0.05). The hypoxic exercise-induced cerebral vasodilatory response was blunted by HBR, probably because of the marked hyperventilation-dependent hypocapnia, attendant to the sustained hypoxic stimulus. Hence, short-term exposure to hypoxia potentiates the reduction in V̇O2 peak , but it mitigates the impairment in skeletal muscle oxidative capacity induced by bedrest.

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“…McDonnell et al . ; Keramidas et al . ), it is an area that is worthy of more attention, as is the associated field of ‘cross‐adaptation’.…”

Section: Introductionmentioning

confidence: 99%

Environmental extremes: origins, consequences and amelioration in humans

Tipton

2015

Experimental Physiology

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New Findings r What is the topic of this review?This review concerns human responses to extreme environmental stresses. r What advances does it highlight?This review highlights the following factors: the relatively limited and varying value of adaptation; the value of research in this area to inform other medical conditions; the physiological pathways to drowning; the importance of multistressor studies and multistressor adaptation; and the need for a better understanding of the metabolomic and biomolecular basis of responses and their variation in extreme environments.Professor Sir George Lindor Brown (1903-1971) is known for his pioneering research into cholinergic neuromuscular transmission. However, during World War II he worked in hyperbaric physiology, and his research into underwater physiology greatly improved the safety of divers. It is perhaps fitting, therefore, that this review, which accompanies the Physiological Society's G. L. Brown Prize Lecture for 2015, explores the impact and mitigation of the environmental stresses which, to varying extents, have shaped our past, threaten our present and inform our future. From a whole-body, integrative perspective, this review examines our current understanding of microgravity, hypo-and hyperbaria, heat, cold air and cold water as both individual and combined stresses. Consideration is given to ways of mitigating the threat posed by environmental extremes, including the differing extents to which humans can demonstrate adaptation to them. Finally, recommendations for further study are suggested that might result in both direct and indirect insights.

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Circadian rhythm of peripheral perfusion during 10-day hypoxic confinement and bed rest

Abstract: Daytime vasoconstriction induced by hypoxia and/or bed rest is abolished at night, lending further support to the theory that changes in peripheral skin temperature may be functionally linked to sleep onset.

Cited by 22 publications

References 32 publications

Effects of normobaric hypoxic bed rest on the thermal comfort zone

Effects of normobaric hypoxic bed rest on the thermal comfort zone

LunHab: interactive effects of a 10 day sustained exposure to hypoxia and bedrest on aerobic exercise capacity in male lowlanders

Environmental extremes: origins, consequences and amelioration in humans

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