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Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans.
J Appl Physiol (1985). 2011 Jan; 110(1):157-65.JA

Abstract

We examined whether less convective heat loss during exercise at high altitude than at sea level was partially caused by reduced cutaneous vasodilation due to enhanced plasma water loss into contracting muscles and whether it was caused by hypoxia rather than by hypobaria. Seven young men performed cycling exercise for 40 min at 50% peak aerobic power in normoxia at (710 mmHg) 610 m, determined before the experiments, in three trials: 1) normobaric normoxia at 610 m (CNT), 2) hypobaric hypoxia [low pressure and low oxygen (LPLO)] at 3,200 m (510 mmHg), 3) normobaric hypoxia [normal pressure and low oxygen (NPLO)] at 610 m, in an artificial climate chamber where atmospheric temperature and relative humidity were maintained at 30°C and 50%, respectively. Subjects in CNT and LPLO breathed room air, whereas those in NPLO breathed a mixed gas of 14% O₂ balanced N₂, equivalent to the gas composition in LPLO. We measured change in PV (ΔPV), oxygen consumption rate (Vo₂), mean arterial blood pressure (MBP), esophageal temperature (T(es)), mean skin temperature (T(sk)), forearm skin blood flow (FBF), and sweat rate (SR) during exercise. Although Vo₂, MBP, T(sk), and SR responses during exercise were similar between trials (P > 0.05), the sensitivity of forearm vascular conductance (FBF/MBP) in response to increased T(es) was lower in LPLO and NPLO than in CNT (P < 0.05), whereas that of SR was not, resulting in a greater increase in T(es) from minute 5 to 40 of exercise in LPLO and NPLO than in CNT (P = 0.026 and P = 0.011, respectively). ΔPV during exercise was twofold greater in LPLO and NPLO than in CNT. These variables were not significantly different between LPLO and NPLO. Thus reduced convective heat loss during exercise at 3,200 m was partially caused by reduced cutaneous vasodilation due to enhanced PV loss. Moreover, this may be caused by hypoxia rather than by hypobaria.

Authors+Show Affiliations

Department of Sports Medical Sciences, Institute on Aging and Adaptation, Shinshu University Graduate School, Matsumoto, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21088208

Citation

Miyagawa, Ken, et al. "Reduced Hyperthermia-induced Cutaneous Vasodilation and Enhanced Exercise-induced Plasma Water Loss at Simulated High Altitude (3,200 M) in Humans." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 110, no. 1, 2011, pp. 157-65.
Miyagawa K, Kamijo Y, Ikegawa S, et al. Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans. J Appl Physiol (1985). 2011;110(1):157-65.
Miyagawa, K., Kamijo, Y., Ikegawa, S., Goto, M., & Nose, H. (2011). Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans. Journal of Applied Physiology (Bethesda, Md. : 1985), 110(1), 157-65. https://doi.org/10.1152/japplphysiol.00950.2010
Miyagawa K, et al. Reduced Hyperthermia-induced Cutaneous Vasodilation and Enhanced Exercise-induced Plasma Water Loss at Simulated High Altitude (3,200 M) in Humans. J Appl Physiol (1985). 2011;110(1):157-65. PubMed PMID: 21088208.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans. AU - Miyagawa,Ken, AU - Kamijo,Yoshi-Ichiro, AU - Ikegawa,Shigeki, AU - Goto,Masaki, AU - Nose,Hiroshi, Y1 - 2010/11/18/ PY - 2010/11/20/entrez PY - 2010/11/23/pubmed PY - 2011/8/4/medline SP - 157 EP - 65 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 110 IS - 1 N2 - We examined whether less convective heat loss during exercise at high altitude than at sea level was partially caused by reduced cutaneous vasodilation due to enhanced plasma water loss into contracting muscles and whether it was caused by hypoxia rather than by hypobaria. Seven young men performed cycling exercise for 40 min at 50% peak aerobic power in normoxia at (710 mmHg) 610 m, determined before the experiments, in three trials: 1) normobaric normoxia at 610 m (CNT), 2) hypobaric hypoxia [low pressure and low oxygen (LPLO)] at 3,200 m (510 mmHg), 3) normobaric hypoxia [normal pressure and low oxygen (NPLO)] at 610 m, in an artificial climate chamber where atmospheric temperature and relative humidity were maintained at 30°C and 50%, respectively. Subjects in CNT and LPLO breathed room air, whereas those in NPLO breathed a mixed gas of 14% O₂ balanced N₂, equivalent to the gas composition in LPLO. We measured change in PV (ΔPV), oxygen consumption rate (Vo₂), mean arterial blood pressure (MBP), esophageal temperature (T(es)), mean skin temperature (T(sk)), forearm skin blood flow (FBF), and sweat rate (SR) during exercise. Although Vo₂, MBP, T(sk), and SR responses during exercise were similar between trials (P > 0.05), the sensitivity of forearm vascular conductance (FBF/MBP) in response to increased T(es) was lower in LPLO and NPLO than in CNT (P < 0.05), whereas that of SR was not, resulting in a greater increase in T(es) from minute 5 to 40 of exercise in LPLO and NPLO than in CNT (P = 0.026 and P = 0.011, respectively). ΔPV during exercise was twofold greater in LPLO and NPLO than in CNT. These variables were not significantly different between LPLO and NPLO. Thus reduced convective heat loss during exercise at 3,200 m was partially caused by reduced cutaneous vasodilation due to enhanced PV loss. Moreover, this may be caused by hypoxia rather than by hypobaria. SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/21088208/Reduced_hyperthermia_induced_cutaneous_vasodilation_and_enhanced_exercise_induced_plasma_water_loss_at_simulated_high_altitude__3200_m__in_humans_ L2 - https://journals.physiology.org/doi/10.1152/japplphysiol.00950.2010?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -