Accurate monitoring of electrolyte loss during exercise is critical for guiding hydration strategies, maintaining performance, and reducing the risk of electrolyte deficiency disorders. Electrolyte deficiencies, particularly in sodium, potassium, and chloride, can lead to muscle cramps, fatigue, impaired neuromuscular function, arrhythmias, and, in severe cases, life-threatening complications such as hyponatremia. While several commercially available sweat-testing devices, including the LEVELENâ„¢ Sweat Test, Gx Sweat Patch, Nix Biosensor, and hDrop Hydration Monitor, claim to provide individualized electrolyte data, their accuracy compared with standard blood serum testing has not been systematically evaluated. This study aims to assess the validity and reliability of these devices by comparing their results to changes in serum electrolytes measured before and after exercise. Methods: Participants will undergo a baseline venous blood draw to measure sodium, potassium, and chloride levels followed by a standardized 60-minute treadmill session while wearing the sweat-testing devices. A second blood draw will follow exercise to capture exercise-induced electrolyte shifts. Device outputs will be compared against serum results and evaluated statistically using a paired t-test and Friedman test to assess differences in agreement across devices and serum results. We hypothesize that sweat-testing devices will show variable agreement with blood-based measures, with certain devices demonstrating closer accuracy and reliability than others. Findings from this study will provide a systematic evaluation of sweat electrolyte testing technologies against the current clinical gold standards and inform evidence-based recommendations for athletes, coaches, and clinicians seeking effective hydration and electrolyte monitoring tools.
