Hydration sensor could improve health and performance of tactical athletes

In the world of tactical performance—where military readiness, emergency response, and law enforcement precision intersect with extreme environmental stress—physical hydration can be the difference between peak performance and critical failure. Dr. Joel Martin, Director of Operations, at the Sports Medicine Assessment Research and Testing (S.M.A.R.T.) Laboratory and an associate professor of Kinesiology at George Mason University, is at the forefront of research and development to improve monitoring of dehydration among tactical athletes. 

Since joining George Mason in 2012, Dr. Martin has built a research portfolio focused on applied physiology and wearable technology. His work has delved into how the human body performs under physical strain, including studies on strength training, biomechanics, and occupational performance in challenging environments. Martin’s career reflects a commitment to translating academic research into practical tools that serve high-performance populations, from elite athletes to military personnel.

Dr. Martin is the primary investigator on an ambitious project: the development of a microneedle-based wearable hydration sensor designed to provide continuous, non-invasive monitoring of hydration levels for use in high-stress, high-heat environments. The hydration sensor itself is being developed by Intelligent Optical Systems and the work is funded by the Office of Naval Research. This sensor isn’t just another consumer fitness gadget – it’s being built specifically for the needs of military members, firefighters, and law enforcement officers who often operate in situations where stopping for a drink of water isn’t an option.

Take firefighters, for instance. While battling blazes in full turnout gear, their bodies sweat profusely without any opportunity to hydrate mid-task. The focus of their gear is physical protection, not breathability, which further increases the risk of dehydration. Dr. Martin spoke to the use case of Naval pilots, who may spend up to eight hours in the cockpit and lack a urine voiding option, leading many to start their missions dehydrated on purpose to avoid discomfort. Yet, research shows that losing just 2% of body weight through fluid loss can impair cognitive function and reaction time—both critical for decision-making under pressure.

One of the goals of this work is to develop a sensor that will monitor hydration in real time, even in challenging conditions. Dr. Martin and his team have tested the hydration sensor on various parts of the body and found that location is insignificant when it comes to measurement but may matter for professional functionality. He imagines that the ideal placement would be on the forearm for easy application while also keeping it out of the way of helmets, gloves, and equipment worn on the torso. Similar to a continuous glucose monitor, the device will provide a steady stream of data on hydration biomarkers such as pH, sodium concentration, and water activity in interstitial fluid. (This is in significant contrast to the current point-in-time testing that requires a urine sample.) In the future, this information could be shared remotely with operational teams to assess job readiness, prevent hydration-related decline before it starts, and remove professionals for the front lines when they need a break. 

However, developing such technology isn’t without its hurdles. Scientific research funding is under increasing scrutiny and subject to political headwinds. The Trump administration’s past budget-cutting approach has cast uncertainty over future grants and support for applied military science. From a technical standpoint, establishing baseline hydration is also incredibly personalized—sweat rates can vary widely based on gender, an individual’s fitness level, diet, and electrolyte status. Plus, physiological responses lag behind behavioral interventions; even after drinking a bottle of water, it can take up to an hour before the body reflects improved hydration status.

Despite these obstacles, Dr. Martin believes in the long-term vision. The goal is a future where hydration is no longer a guessing game but a measurable, trackable metric—especially for those whose lives and missions depend on optimal physical and mental performance.

“Right now, we’re still about five years out from a commercially available product,” Martin said, “but this is about giving people in critical roles the tools they need to stay safe and perform at their best—even in the most extreme conditions.”

As wearable technology continues to evolve innovations like this hydration sensor represent a critical advancement in safeguarding the health and effectiveness of those who serve on the front lines.

Katie D. McMillan, MPH is the CEO of Well Made Health, LLC, a business strategy consulting firm for health technology companies. She is also a curious researcher and writer focusing on digital health evidence, healthcare innovation, and women’s health. Katie can be reached at [email protected] or LinkedIn.