The composition of human sweat is highly variable, both between individuals and within an individual over time. However, sodium and chloride are the major electrolytes lost in sweat, with other ions being present in smaller amounts relative to the whole body status. The sweat electrolyte composition of an individual seems to be related primarily to sweat rate but can be influenced by training status, extent of heat acclimation, and diet. However, the range of values for sweat electrolyte composition reported in the literature probably reflects not only the interindividual differences but also differences in the methodology used for collection of the sweat. This last factor may be the result of errors caused by contamination or incomplete collection of the sample, or it may reflect a real difference induced by the collection procedure.
Due to the secretion and reabsorption process involved in sweat production within the sweat gland and duct, sweat composition is influenced by sweat rate, at least within single ducts, such that a reduction in rate allows for greater reabsorption of certain electrolytes (Na+, Cl_, but not K+) from the duct resulting in a lower concentration in the final sweat produced. There also appear to be regional variations in sweat composition, as evidenced by the different values obtained when the composition of sweat obtained from different parts of the body is compared, and the values obtained by regional collection also differ from those obtained by the whole body washdown technique. Reported values for sweat electrolyte composition are summarized in Table 3.
Was this article helpful?