Feasibility Study of Hydration Monitoring Using Microwaves–Part 2: Measurements of Athletes

Hydration is a key consideration for athletes, where even mild levels of dehydration may negatively impact performance. Existing methods of assessment are either inaccurate or impractical for use in field settings, motivating the search for new approaches. Extremity microwave measurement is a promising method for ongoing hydration monitoring, owing to the inherent differences in dielectric properties with varying tissue water content. This paper reports on a feasibility study of in vivo hydration assessment using microwave measurements in athletes undergoing acute water loss during exercise. We developed and then tested a system for performing reliable microwave property estimation at the forearm. This system was used to measure hydration status in varsity wrestlers before and after a training session. A relationship between estimated permittivity and body weight change due to water loss was found, showing promise for the use of microwaves to assess hydration status. No significant relationship with attenuation was found. A novel method of assessing changes in hydration status is described, which may be of practical use for athletes in guiding fluid replacement during and after exercise.