Protecting the Force: USU Studies Blast Overpressure Risk in Special Operations Forces and Female and Male Bomb Disposal Technicians

USU expands blast overpressure research, focusing on previously underrepresented military personnel, including female EOD technicians and Special Warfare Combatant Craft operators.

Two Special Warfare Combatant-Craft (SWCC) navigate a waterway while a crewman on the lead boat fires a mounted heavy machine gun, producing a visible orange muzzle flash.

SWCC operators have reported symptoms similar to those experienced by heavy weapons instructors, including

an inability to walk straight and think clearly after extended high-speed boat operations and heavy weapons

firing. (U.S. Navy photos by Michael Williams/RELEASED)

January 8, 2026 by Hadiyah Brendel

Research into the neurological effects of blast overpressure is entering a new phase at the Uniformed Services University of the Health Sciences (USU), where investigators are expanding their scope to study military personnel previously understudied in blast health research.

Dr. Michael Roy, the deputy director of the Military Traumatic Brain Injury Initiative (MTBI2) and director of the Department of Medicine Division of Military Medicine, USU, led the foundational INVICTA study and is now directing two ongoing efforts: BLAST EMFASIS and BOATS. These studies target two distinct populations with unique exposure profiles: female and male Explosive Ordnance Disposal (EOD) technicians, and Special Warfare Combatant Craft (SWCC) operators.

BLAST EMFASIS: Expanding the Scope of Blast Research

The BLAST EMFASIS (Baseline and Longitudinal Assessment STudy of EOD Males and Females for Alterations in Symptoms, Intellectual and Sensory Function) study is among the first to examine the acute effects of blast overpressure exposure in female EOD technicians.

“All the studies I’ve done and other people have done, with Navy SEALs, Army Rangers – they’re all male,” Roy explained. “There’s reason to believe that there may be a difference in how women are impacted compared to men.”

The study measures and assesses the acute effects of blast overpressure exposure in 50 male and 50 female EOD personnel across all four service branches. Following baseline assessments, participants wear blast sensors during the course of their normal duties and deployments throughout the two-year study period. When a blast overpressure event is detected, both the study team and the participant are alerted, prompting a follow-up assessment, either in-person or remotely. Assessments are conducted one to four days after the exposure, and again six to 14 days after the exposure.

To accommodate operational reality and EOD personnel dispersal, the study shifted its biomarker collection strategy. Instead of traditional blood tests that require specialized drawing capabilities, the study utilizes saliva samples. This method provides a non-invasive, practical method for collecting biological markers from EOD personnel dispersed across the country with unpredictable exposure rates. The saliva is collected in a tube, flash-frozen, and shipped to a specialized San Diego lab for analysis of brain injury biomarkers.

A female Explosive Ordnance Disposal (EOD) technician in full tactical gear kneels next to a white shipping container, managing a spool of wire during a training exercise, while another service member crouches near a vehicle tire in the background.

The BLAST EMFASIS study is among the first to examine the acute effects of blast overpressure exposure in

female Explosive Ordnance Disposal (EOD) technicians. (U.S. Air Force photo by Airman 1st Class Hunter

C. Kirkland)

BOATS: Analyzing Dual-Threat Forces in SWCC Operators

The BOATS (Blast Overpressure, Acceleration and Cognitive Testing in SWCC) study documents the neurological effects of acceleration and blast overpressure exposure in 40–60 Special Warfare Combatant Craft (SWCC) operators and crewmen. These operators face a combination of hazards unique to their operational role.

Roy described the constant environmental exposure: “They’re driving boats very quickly at 40-60 miles an hour on the ocean. They’re hitting waves at that speed. It’s constant reverberation, like being on a roller coaster for hours.” The neurological impact comes from the combination of acceleration (from high-speed wave impact) and blast (from firing heavy weapons), an exposure profile that is unique and largely unexamined.

SWCC operators have reported symptoms similar to those experienced by heavy weapons instructors, including an inability to walk straight and think clearly after extended high-speed boat operations and heavy weapons firing.

Those self-reports are underscored by a sobering fact: Roy reports the worst case of Chronic Traumatic Encephalopathy (CTE) ever seen by USU neuropathologists was found in a SWCC operator.

BOATS will use two different types of gauges: the B3 Blackbox Biometrics blast gauges used in the Investigating Training Associated Blast Pathology, or INVICTA, and a PREVENT Biometrics mouthguard gauge to specifically measure the impact and force of the waves hitting the boat. Data collection begins December 2025 and will continue across multiple locations nationwide. The study also examines whether these effects differ across locations using miniguns compared to those using other heavy weapons. Assessments are conducted at baseline, and again immediately upon return from boat operations as well as both 24- and 96-hours post-exposure.

Tools for Post-Exposure Screening

A key focus of both studies is validating a suite of objective tests that are rapid and easily administered in any field environment, providing critical data to inform Return-to-Duty decisions. Roy emphasized the criteria for effective tools: quick, easy, reliable.

Mind Mirror (Oculomotor Test): This test monitors pupil response to a flash of light and can be done via an app on a cellphone. The speed and objective scoring make it ideal for immediate post-exposure screening.
Pison Wristband (Go/No-Go): This watch-like device measures quickness and inhibitory control by testing reaction time to colored lights. The goal is to see if brain function is impacted to the degree that a warfighter struggles with split-second decisions—like determining whether to shoot or wait.
AccWalker (Neuromotor Test): This assessment uses a cell phone strapped to the thigh to measure deviations while the participant marches in place with eyes closed.
Brain Gauge (Somatosensory Test): This computer mouse-like device uses vibrations to test tactile discrimination, which is highly sensitive to subtle neurological changes.
Hopkins Verbal Learning Test–Revised (Cognitive Test): This is a list of 12 words that are read aloud and the participant is asked to repeat back as many of them as they can remember; this is repeated 3 times in rapid succession.

The Pison wristband test integrates military operational experience, receiving input from a former Army Ranger command sergeant major to develop its field-ready neural biosensing capabilities. These operationally practical assessment tools, derived from the military community, are the type of tests Roy says are needed. He notes the Mind Mirror test as one of his “favorites” since it only takes seven seconds and provides data right away.

BLAST EMFASIS will also utilize the NIH Toolbox Neurocognitive Assessment, a suite of seven computer-based tests, to assess the subtle cognitive impact of blast exposure on EOD personnel. This extensive tool, which includes tasks like picture memory and sequencing, previously distinguished between TBI, PTSD, and healthy controls in military populations. The goal is to determine if the NIH Toolbox can reliably identify changes in brain function within the context of blast exposure.

A speed boat full of military service members in an overhead shot.

“They’re driving boats very quickly at 40-60 miles an hour on the ocean. They’re hitting waves at that speed.

It’s constant reverberation, like being on a roller coaster for hours,” says Roy. (U.S. Navy photo by

Mass Communication Specialist 2nd Class Eric Coffer/Released)

Future Focus: Protection and Policy Change

Ultimately, Roy hopes these studies prove the efficacy of these simple, objective tests so they can be adopted widely and practically. “Hopefully we can find ways to better protect the brains of service members. That's really the goal,” Roy said.

For instance, findings from the BOATS study could lead to practical countermeasures for SWCC operators, including engineering more absorbent material into the boats to mitigate acceleration, operational adjustments such as reducing daily high-intensity exposure, substituting live rounds with training rounds, and redefining crew positioning to minimize blast exposure.

The BLAST EMFASIS study is expected to yield crucial data for establishing objective, rapid assessments and personalized safety guidelines for EOD personnel. The two-year, longitudinal data collection, including the comparison between male and female warfighters, will be essential in developing gender-informed safety protocols and establishing cumulative lifetime exposure limits to help mitigate chronic neurological injury.

Both studies will identify the impact of blast overpressure exposure on these unique populations and guide mitigation, allowing the DoW to validate changes in training, equipment, and operations to ensure the long-term health and readiness of the force.