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- Sotiridis, Alexandros, et al.
(author)
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Exercise cardiorespiratory and thermoregulatory responses in normoxic, hypoxic and hot environment following 10-day continuous hypoxic exposure
- 2018
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In: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 125:4, s. 1284-1295
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Journal article (peer-reviewed)abstract
- We examined the effects of acclimatization to normobaric hypoxia on aerobic performance and exercise thermoregulatory responses under normoxic, hypoxic and hot conditions. Twelve males performed tests of maximal oxygen uptake (V̇O2max) in normoxic (NOR), hypoxic (13.5% FiO2; HYP) and hot (35℃, 50% RH; HE) conditions in a randomized manner before and after a 10-day continuous normobaric hypoxic exposure (FiO2 = 13.65(0.35)%, PiO2 = 87(3) mmHg). The acclimatization protocol included daily exercise (60min @ 50% hypoxia-specific peak power output, Wpeak). All maximal tests were preceded by a steady-state exercise (30 min at 40% Wpeak) to assess the sweating response. Hematological data were assessed from venous blood samples obtained before and after acclimatization. V̇O2max increased by 10.7% (P = 0.002) and 7.9% (P = 0.03) from pre- to post-acclimatization in NOR and HE, respectively, whereas no differences were found in HYP (pre: 39.9(3.8) vs post: 39.4(5.1) mL.kg-1.min-1, P = 1.0). However, the increase in V̇O2max did not translate into increased Wpeak in either NOR or HE. Maximal heart rate and ventilation remained unchanged following acclimatization. Νo differences were noted in the sweating gain and thresholds independent of the acclimatization or environmental conditions. Hypoxic acclimatization markedly increased hemoglobin (P < 0.001), hematocrit (P < 0.001) and extracellular HSP72 (P = 0.01). These data suggest that 10 days of normobaric hypoxic acclimatization combined with moderate-intensity exercise training improves V̇O2max in NOR and HE, but does not seem to affect exercise performance or thermoregulatory responses in any of the tested environmental conditions.
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| 4. |
- Stavrou, Nektarios A. M., et al.
(author)
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Hypoxia Exacerbates Negative Emotional State during Inactivity : The Effect of 21 Days Hypoxic Bed Rest and Confinement
- 2018
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In: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 9
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Journal article (peer-reviewed)abstract
- Hypoxia and confinement have both been shown to influence emotional state. It is envisaged that the inhabitants of future planetary habitats will be exposed to concomitant confinement, reduced gravity and hypoxia. We examined the independent and combined effects of a 21-day inactivity/unloading and normobaric hypoxia under confined conditions on various psychological factors. Eleven healthy men participated in three 21-day experimental campaigns designed in a cross-over manner (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bed rest and (3) Normobaric normoxic bed rest. The Profile of Mood States, and the Positive and Negative Affect Schedule were employed to assess the participants' psychological responses before (Pre), during (Day 7, Day 14, and Day 21) and after (Post) the confinements. The most negative psychological profile appeared on days 14 and 21 of the hypoxic bed rest campaign. A significant increase in depression, tension, and confusion was noted on days 14 and 21 of the hypoxic bed rest condition. Concomitantly, a decrease, albeit not statistically significant, in positive psychological responses was observed. The psychological profile returned to the initial level at Post following all confinements. These data suggest that the combined effect of hypoxia and bed rest induced the most negative effects on an individual's mood. However, significant intra- and inter-individual differences in psychological responses were noted and should be taken into consideration.
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