The influence of acute and 23 days of intermittent hypoxic exposures on the exercise-induced forehead sweating response
2007 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 99, no 5, 557-566 p.Article in journal (Refereed) Published
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 (VO2(peak)) 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 (VO2(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 (m(sw)f) 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 (m(sw)f/Delta T(re)). The augmented (m(sw)f) and m(sw)f/Delta T(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.
Place, publisher, year, edition, pages
2007. Vol. 99, no 5, 557-566 p.
Exercise thermoregulation, Non-thermal sweating, Intermittent normobaric hypoxia, Perceived exertion, Relative work rate
IdentifiersURN: urn:nbn:se:kth:diva-44579DOI: 10.1007/s00421-006-0364-9ISI: 000243970400012PubMedID: 17242947OAI: oai:DiVA.org:kth-44579DiVA: diva2:451274
QC 201111022011-10-252011-10-252011-11-02Bibliographically approved