USARIEM investigates a way for service members to remain effective in the cold

NATICK, MA, UNITED STATES

05.02.2024

Story by Maddi Langweil 

Medical Research and Development Command

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Have you ever been out in the bitter cold when your normally nimble fingers feel more like clumsy paws? For Warfighter’s this is not only frustrating but can have serious adverse effects.

Frigid temperatures can affect the extremities, turning the simplest tasks into formidable challenges. The U.S. Army Research Institute of Environmental Medicine researchers are dedicated to investigating ways for Warfighters to remain effective in these types of environments.

“Impaired manual dexterity and hand function in the cold has severe adverse effects on the ability to perform important military tasks such as digital command-and-control functions, weapons use and delivery of medical treatment,” says Afton Seeley, Ph.D., a Research Physiologist and Principal Investigator in the Thermal & Mountain Medicine Division at the USARIEM. “While gloves provide some reprieve, they ultimately blunt manual dexterity and precise task completion. Other active warming countermeasures require a power component that can lend to considerable technical limitation within a field setting, especially in a battery-draining cold environment.”

Seeley is investigating the use of vascular conditioning as a countermeasure meant to improve manual dexterity in uncomfortably cold temperatures. The technique uses a blood pressure cuff to cyclically reduce blood flow for 5-minutes before restoring normal flow. Altering blood flow is intended to ‘condition’ or ‘train’ blood vessels to reduce their usual narrowing response to environmental cold that lend to difficulty with hand function.

A typical vascular conditioning procedure involves using pressure cuffs that block or unblock normal blood flow when inflated. The pressure-based cuff systems are relatively simple and could potentially be put under or even built into a Soldier’s sleeve.

In Seeley’s study, a single vascular conditioning exposure consists of four cycles of imposed pressure for 5-minutes followed by 5-minutes of reperfusion for a total of 40 minutes. The study design seeks to investigate the ‘dose-response’ of both a single exposure as well as five consecutive days of exposure on hand blood flow, manual dexterity and thermal perception.

“We hypothesized that five days of vascular conditioning would improve blood flow and skin temperatures in response to cold air and cold-water immersion and subsequently lend to improvements in manual dexterity tasks such as magazine loading and hand/finger pinch strengths,” Seeley said.

Within the environmental chambers at USARIEM, Seeley and the team conduct their study in thermal chambers capable of maintaining study-specific freezing air temperatures (32°F) with 3 mph wind speeds. Each volunteer is asked to complete four experimental trials each with an identical two-part cold testing battery. The cold test battery is preceded by a single vascular conditioning intervention, a 5-day vascular conditioning procedure, or no pre-cold intervention. The first cold test battery involves immersing both hands in 46°F water for 30 minutes to evaluate the ability of vascular conditioning to modify the neural and perceptual components of cold exposure.

After a rewarm, volunteers complete a 90-minute 32°F passive air exposure dressed in winter weather clothing with bare hands. While exposed they periodically complete dexterity tests as skin temperatures cool.

The application could conveniently be conducted in an indoor environment before performing manual-dexterity-demanding tasks in colder environments.

“It may prove to be an inexpensive and logistically superior countermeasure to employ prior to cold exposure,” Seeley noted. “Ultimately, if vascular conditioning provides significant improvement in manual dexterity and cold tolerance, it will be transitioned to use with field medics in units such as the 11th Airborne, Alaska.”

USARIEM is a subordinate command of the U.S. Army Medical Research and Development Command under the Army Futures Command. USARIEM is internationally recognized as the DOD's premier laboratory for Warfighter health and performance research and focuses on environmental medicine, physiology, physical and cognitive performance, and nutrition research. Located at the Natick Soldier Systems Center in Natick, Massachusetts, USARIEM's mission is to provide solutions to optimize Warfighter health and performance through biomedical research.