The sweat secretion and sodium loss quadrant: a concept for predicting hydration requirements
It is well known that, for some physically-demanding occupations and some long-duration athletic pursuits, individuals must consider not just fluid replacement, but also electrolyte replacement. Of the solutes contained within sweat, sodium and chloride are dominant (Patterson et al., 2000). However, whilst one can easily determine water replacement on the basis of mass changes, it can be difficult to determine, in the absence of sophisticated analysis equipment, how much sodium an individual should replace. It occurred to us that one may be able to predict this simply on the basis of the steady-state exercise intensity (heart rate), and herein we report how one may achieve such a prediction.