Journal of Applied Physiology, Vol 68, Issue 2 659-664, Copyright © 1990 by American Physiological Society
Changes in insulation of body tissue and wet suits during underwater exercise at various atmospheric pressures
J. Iwamoto, S. Sagawa, F. Tajima, K. Miki, H. Tanaka and K. Shiraki
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
To clarify the independent changes of insulations of body tissues (Itissue)
and wet suit (Isuit) in the wet-suited subject during underwater exercise,
overall heat flow from the skin (Htissue) and wet suit (Hsuit) and
esophageal (Tes), skin (Tsk), and wet suit temperatures were measured at 1,
2, and 2.5 atmospheres absolute (ATA) at critical water temperature (Tcw).
The average Tcw in nine wet-suited men (23-38 yr) was 22.3 +/- 0.2, 26.3
+/- 0.2, and 28.0 +/- 0.4 degrees C (SE) at 1, 2, and 2.5 ATA,
respectively. At Tcw of each pressure male volunteers wearing 5-mm neoprene
wet suits completed three 2-h experiments while immersed up to the neck.
During one experiment the subjects remained at rest, and in the other two
they exercised on an underwater ergometer at two different intensities (2
and 3 met). Tes significantly declined (P less than 0.05) over 2 h from
37.1 to 36.5 degrees C during rest in each pressure. The 2-met exercise
prevented Tes from falling in all pressures, and the 3-met exercise
elevated Tes by 0.2-0.3 degrees C. There was no exercise-dependent
difference in Isuit, but a pressure-dependent difference was remarkable.
The Itissue at rest was identical for all pressures; however, it
progressively decreased as a function of exercise intensity. It is
concluded that overall Itissue is entirely determined by work intensity at
Tcw, but not by atmospheric pressure. On the contrary, Isuit at Tcw is
solely dependent on the pressure, but not on the work intensity.
