Journal of Applied Physiology, Vol 67, Issue 6 2473-2480, Copyright © 1989 by American Physiological Society
Conductive and convective heat flows of exercising humans in cold water
G. Ferretti, A. Veicsteinas and D. W. Rennie
Department of Physiology, Centre Medical Universitaire, Geneva, Switzerland.
The apparent conductance (Kss, in W.m-2.degrees C-1) of a given region of
superficial shell (on the thigh, fat + skin) was determined on four
nonsweating and nonshivering subjects, resting and exercising (200 W) in
water [water temperature (Tw) 22-23 degrees C] Kss = Hss/(Tsf-Tsk) where
Hss is the skin-to-water heat flow directly measured by heat flow
transducers and Tsf and Tsk are the temperatures of the subcutaneous fat at
a known depth below the skin surface and of the skin surface, respectively.
The convective heat flow (qc) through the superficial shell was then
estimated as qc = (Tsf - Tsk).(Kss - Kss,min), assuming that at rest Kss
was minimal (Kss,min) and resting qc = 0. The duration of immersion was set
to allow rectal temperature (Tre) to reach approximately 37 degrees C at
the end of rest and approximately 38 degrees C at the end of exercise.
Except at the highest Tw used, Kss at the start of exercise was always
Kss,min and averaged 51 W.m-2.degrees C-1 (range 33-57 W.m-2.degrees C-1)
across subjects, and qc was zero. At the end of exercise at the highest Tw
used for each subject, Kss averaged 97 W.m-2.degrees C-1 (range 77-108
W.m-2.degrees C-1) and qc averaged 53% (range 48-61%) of Hss (mean Hss =
233 W.m-2).(ABSTRACT TRUNCATED AT 250 WORDS)
