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The influence of exercise‐induced dehydration on thermal sensation and comfort
Author(s) -
Nagashima Kei,
Tokizawa Ken,
Yasuhara Saki,
Nakamura Mayumi,
Crawshaw Larry
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.956.20
Subject(s) - thermoregulation , dehydration , thirst , thermal sensation , skin temperature , chemistry , perspiration , thermal comfort , sensation , hypertonic saline , plasma osmolality , sed , zoology , medicine , psychology , sodium , biology , biochemistry , biomedical engineering , meteorology , neuroscience , physics , organic chemistry , psychiatry
[Introduction] Dehydration attenuates autonomic thermoregulation in the heat such as sweating and skin blood flow in human. Hyperosmolality in the extracellular fluid is thought to be involved in this mechanism. In contrast, behavioral thermoregulation (i.e. heat escape behavior) is augmented after hypertonic‐saline injection in rats (Nagashima et al., Am J Physiol 2001). However, it remains unknown if human activate behavioral thermoregulation during dehydration. [Methods] Ten healthy young men participated in the present study. Body and skin temperature were monitored. Rating for thermal sensation and comfort were conducted. After ~45 min rest at 27°C, they did 50‐min ergometer exercise, which was at the level of 40% peak VO 2 or ~15% peak VO 2 at an ambient temperature of 35°C or ~24°C, respectively. Subjects returned to the rest at 27°C until body and skin temperature being restored. Ambient temperature was then changed from 22°C to 38°C. [Results] Body weight decreased by 1.1 ± 0.1% after the exercise at 35°C and 0.2 ± 0.1% at ~24°C. Plasma osmolality increased by 6 ± 1 mosmol/kg•H 2 O at 35°C, but did not change at ~24°C. Thermal sensation and comfort in the heat were augmented (i.e. feeling hotter and more uncomfortable) after the exercise at 35°C. [Conclusion] Dehydration increases thermal sensation and comfort in the heat in human, which are closely related to behavioral thermoregulation.