Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability

Sweating rate and sweat composition vary considerably within and between athletes, and sweat tests are used to personalise fluid and electrolyte advice — but unstandardised methods and field conditions can make results inconsistent or inaccurate. The review covers how laboratory and field methods affect sweating rate and sweat sodium concentration.

The simplest and most accurate way to get whole-body sweating rate is the change in body mass during exercise, corrected for non-sweat mass changes and sweat trapped in clothing. Sweat sodium varies with the collection system (whole body or localised), the timing and duration of collection, skin cleaning, sample storage and handling, and the analytical technique.

The review also lists factors that change sweating rate and sweat sodium within and between people, from exercise intensity and environment to heat acclimation, fitness, body size, protective equipment, sex, maturation, ageing, diet and hydration. Sweat testing is useful if data are collected, analysed and interpreted appropriately.

Not applicable (narrative review).