INDICES AND SWEATING PATTERNS FOR THE ASSESSMENT OF HEAT TOLERANCE

Abstract

1) Two kinds of indices are proposed for the assessment of heat tolerance. Indices I and S are calculated utilizing the following equations:
I=√A²+B²+C², S=/√A²+C²
where: A=relative water loss
B=relative rise in body temperature
C=relative salt loss
during the sweating test.
2) Ohara's sweating type method, representing a relation between local sweat rate and sodium concentration in sweat, was modified by using salt loss in place of sodium concentration. Sweating patterns were classified into U, N, and T Types in the Q'(salt loss)-V (peak sweat rate) plane. Type U corresponds to Ohara's Type 1, the least heat tolerant, and Type T corresponds to Ohara's Type 4, the most heat tolerant.
3) Results obtained with the authors' method and Index I coordinated well. Type U showed the highest value of Index I, Type T the lowest which suggest that the lower value of Index I indicates a greater heat tolerance.
4) The three type method and Index S revealed no significant correlation, which suggests that Index S is not a measure to be applied to heat tolerance. It was discussed that Index S may be utilized as an index to represent effectiveness of homeostatic mechanism to thermal regulation.
5) Ohara's four sweating types and Index I showed no significant correlation. Thus, the three-type method appears to be a more satisfactory tool for examining heat tolerance.