The influence of acute and 23 days of intermittent hypoxic exposures on the exercise-induced forehead sweating response

Abstract The effect of acute and 23 days of intermittent exposures to normobaric hypoxia on the forehead sweating response during steady-state exercise was investigated. Eight endurance athletes slept in a normobaric hypoxic room for a minimum of 8 h per day at a simulated altitude equivalent to 2,7...
Ausführliche Beschreibung

Abstract The effect of acute and 23 days of intermittent exposures to normobaric hypoxia on the forehead sweating response during steady-state exercise was investigated. Eight endurance athletes slept in a normobaric hypoxic room for a minimum of 8 h per day at a simulated altitude equivalent to 2,700 m for 23 days (sleep high–train low regimen). Peak oxygen uptake %$ {\left( {\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2{\text{peak}}}} } \right)} %$ and peak work rate ($ WR_{peak} $) were determined under normoxic (20.9%$ O_{2} $) and hypoxic (13.5%$ O_{2} $) conditions prior to (pre-IHE), and immediately after (post-IHE) the intermittent hypoxic exposures (IHE). Also, each subject performed three 30-min cycle-ergometry bouts: (1) normoxic exercise at 50% $ WR_{peak} $ attained in normoxia (control trial; CT); (2) hypoxic exercise at 50% $ WR_{peak} $ attained in hypoxia (hypoxic relative trial; HRT) and (3) hypoxic exercise at the same absolute work rate as in CT (hypoxic absolute trial; HAT). Exposure to hypoxia induced a 33 and 37% decrease (P < 0.001) in %$ \ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}}_{{2{\text{peak}}}} %$ pre-IHE and post-IHE, respectively. Despite similar relative oxygen uptake during HAT pre-IHE and post-IHE, the ratings of perceived whole-body exertion decreased substantially (P < 0.05) post-IHE. Pre-IHE the sweat secretion on the forehead %$ {\left( {\ifmmode\expandafter\dot\else\expandafter\.\fi{m}_{{{\text{sw}}}} f} \right)} %$ was greater (P < 0.01) in the HAT (2.60 (0.80) mg $ cm^{−2} $ $ min^{−1} $) compared to the other two trials (CT = 1.87 (1.09) mg $ cm^{−2} $ $ min^{−1} $; HRT = 1.57 (0.82) mg $ cm^{−2} $ $ min^{−1} $) despite a similar exercise-induced elevation in body temperatures, resulting in an augmented (P < 0.01) gain of the sweating response %$ {\left( {\ifmmode\expandafter\dot\else\expandafter\.\fi{m}_{{{\text{sw}}}} f/\Delta T_{{{\text{re}}}} } \right)}. %$ The augmented %$ \ifmmode\expandafter\dot\else\expandafter\.\fi{m}_{{{\text{sw}}}} f %$ and %$ \ifmmode\expandafter\dot\else\expandafter\.\fi{m}_{{{\text{sw}}}} f/\Delta T_{{{\text{re}}}} %$ during the HAT were no longer evident post-IHE. Thus, it appears that exercise sweating on the forehead is potentiated by acute exposure to hypoxia, an effect which can be abolished by 23 days of intermittent hypoxic exposures. Ausführliche Beschreibung

Autor*in:	Kacin, Alan [verfasserIn] Golja, Petra [verfasserIn] Eiken, Ola [verfasserIn] Tipton, Michael J. [verfasserIn] Mekjavic, Igor B. [verfasserIn]

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2007

Schlagwörter:	Exercise thermoregulation Non-thermal sweating Intermittent normobaric hypoxia Perceived exertion Relative work rate

Übergeordnetes Werk:	Enthalten in: European journal of applied physiology - Berlin : Springer, 1928, 99(2007), 5 vom: 23. Jan., Seite 557-566
Übergeordnetes Werk:	volume:99 ; year:2007 ; number:5 ; day:23 ; month:01 ; pages:557-566

Links:	Volltext

DOI / URN:	10.1007/s00421-006-0364-9

Katalog-ID:	SPR005514797