MX3 Rapid Sweat Test Optimized for USAF Personnel

Proper hydration plays an important role in the safety and performance of warfighters as they perform their duties and mission objectives. A critical part of maintaining proper hydration is knowing which “hydration fuel” to use to optimize fluid balance. Dehydration as little as 2% body mass loss (BML) causes significant performance deficits and much greater dehydration - up to 6% BML - has been reported in short duration (<125mins) training flights and missions. At this level of dehydration there is a great risk of heat exhaustion, heat stroke, loss of consciousness, and organ damage. Furthermore, excessive sodium loss and/or over-consumption of water can cause exercise associated hyponatremia (EAH), which can result in seizures, coma and without treatment, death. This is highlighted by recent tragic deaths due to EAH within the military. Understanding how quickly a warfighter loses sodium via sweat during exertion can guide the development of personalized rehydration strategies that could mitigate or avoid the adverse effects of dehydration and EAH.   The opportunity for personalized rehydration is highlighted by the large variability in exertion related fluid and sodium losses between individuals; for example, sweat rates for adults during exercise typically range from 0.5 to 2.0 L/ hour, and sweat sodium concentrations typically range from 250 mg/L to 2500 mg/L. By determining individual fluid and sodium losses, effective rehydration strategies can be adopted that are more appropriate for each warfighter. In addition, many other factors influence fluid and sodium requirements, including heat acclimatization, diet, exercise intensity and physical fitness, potentially indicating the need for periodic re-assessment of fluid and sodium requirements. Current testing tools for determining sweat sodium concentration are impractical for large cohorts due to the cost, complexity, and time required to provide accurate assessment. These barriers also restrict wider application of sweat sodium testing to monitor effects of other factors that can affect sodium requirements, such as acclimitization. Determination of sweat sodium concentration to develop warfighter-specific rehydration strategies and/or assessing environmental acclimation has the potential to increase performance, mission safety and the likelihood of meeting mission objectives.