Whole body sweat collection in man: an improved method with
preliminary data on electrolyte content.
Shirreffs, S. M., and R. J. Maughan.
University Medical School, Foresterhill, Aberdeen AB9 2ZD,
Scotland
APStracts 3:0368A, 1996.
Previous methods used to collect human sweat for electrolyte analysis
have been criticised because they involve only regional sampling or
because of methodological problems associated with whole body
washdown techniques. An improved method for collection of whole body
sweat from exercising subjects is described. It involved construction
of a plastic frame which supports a large plastic bag within which
the subject exercises. The subject and the equipment are washed with
distilled, deionised water prior to exercise. After exercise, the
subject and equipment are again washed with water containing a marker
not present in sweat (ammonium sulphate). Total sweat loss is
calculated from the change in body mass, and the volume of sweat not
evaporated is calculated from dilution of the added marker. Mean (SD)
recovery of added water was 102(2)% of the added volume, and recovery
of added electrolytes was 99(2)% for sodium, 98(9)% for potassium and
101(4)% for chloride. Repeated trials (n=4) on five subjects to
establish the reproducibility of the method gave a CV of 17(5)% for
sodium, 23(6)% for potassium and 15(6)% for chloride: these values
include the biological variability between trials as well as the
error within the method. The biological variability thus appears to
be far greater than the methodological error. Normal values for the
composition of sweat induced by exercise in a hot, humid environment
in healthy young men and women were: 50.8(16.5)mmol l-1 sodium,
4.8(1.6)mmol l-1 potassium, 1.3(0.9)mmol l-1 calcium, 0.5(0.5)mmol l
-1 magnesium and 46.6(13.1)mmol l-1 chloride.
Received 17 January 1996; accepted in final form 24 July 1996.
APS Manuscript Number A56-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996