USARIEM leads the way in Female Warfighter Research

For more than 60 years, the U.S. Army Research Institute of Environmental Medicine researchers have extensively studied the Warfighter. Included in this is the recognition of the female Warfighter and the importance of exploring sex differences in physiological and psychological responses to specialized stressors Service Members undergo.

During the recent 2024 Military Women’s Symposium—Amplifying Women’s Combat Capacity, hosted by The Valkyrie Project and MIT Lincoln Laboratory, some of USARIEM’s researchers focused on the female Warfighter. Karl Friedl, Ph.D., Holly McClung, MS RDN CSSD, and Gabrielle Giersch, Ph.D., joined the discussion designed to advance dialogue around empowering female Warfighters to meet their full potential.

Serving as the keynote speaker of the Health and Wellness session, Friedl, USARIEM’s Senior Research Scientist and Performance Physiologist, talked about the “Defense Women’s Health and Performance Research: What have we done for Military Women lately?” Friedl highlighted that researchers have investigated female performance topics such as the impact of ovarian hormones, energy balance, body composition, bone health and the risk of stress fractures, strength, equipment design, pregnancy, micronutrition—specifically vitamin D and iron—and so much more.

“Certain things are unique to women in the military,” said Friedl. “For example, women have a physiological advantage in high stress situations due to estrogen-regulated lipid metabolism, raising several follow up questions: Are there measurable advantages in decision making? Is this a metabolic advantage in hot and cold environments? Is lean mass better protected in field deployment conditions?”

Research into female Warfighter health and performance has come a long way, resolving myths and stereotypes, as well as making new discoveries in performance physiology, resilience, and the estrogen advantage.

“Women work just as hard [as men]—they are just more efficient,” said Friedl. “Solutions are being optimized for women and no longer centered on making women fit to legacy male designs.”

McClung challenged the audience to envision the qualities that make up the female elite Warfighter. Strong, hard-working, leaders, smart… these are only a handful of the descriptors called out.

“We’ve come a long way,” said McClung, a Nutritional Physiologist with the Military Performance Division. “In 2019, USARIEM set out to uncover what makes elite female Warfighters successful – we wanted to better understand what these women look like, what motivates them, and how they compare to other Army females (and males) physically and psychologically.”

In August 2015, two female Soldiers made history as they graduated from the U.S. Army Ranger Course, one of the Army’s most difficult leadership trainings. As of this March, less than 10 years later, 132 women wear the Ranger tab.

Physically and mentally, females are built differently than males. But the question is not whether female and male Warfighters are equal in strength but whether they can perform their occupational tasks equally leveraging their strengths.

McClung went on to share outcomes from her research focused on the psychological and sociological profile of elite female Warfighters. “Female Warfighters, especially female elite Warfighters, have an internal drive that is hard for scientists to capture and compare—it is their grit, determination and the willingness to accept the challenge.

“We need to continue to feed unique opportunities to all individuals within our Force – and our society if we really want to shift the mindset – we must build the individuals. We must all rise to the challenge – ‘togetHER we are a stronger team!’” said McClung.

Giersch, Research Physiologist with the Thermal and Mountain Medicine Division, discussed thermoregulation research—heat and cold stress, high altitude/hypoxia, hydration, menstrual cycle, and contraceptive use.

“Women are drastically underrepresented in thermoregulation research,” said Giersch. “We have been doing better in the last couple decades, but we are still very underrepresented. We simply do not have enough data in women to say, with certainty, this is the response of women. What we need is more data so that we can make recommendations that are appropriate for both men and women.”

Current policies and recommendations for women are extrapolated from evidence based on research studies primarily involving men.

There are biophysical differences and physiological differences that impact thermoregulation between men and women. Biophysical differences relate to the differences in body size—on average men are larger than women and have greater body surface area or mass. Physiological differences relate to the way the body thermoregulates in terms of blood flow to the skin and sweating.

“These differences do not mean that women are at an increased risk or that women don’t “perform” as well in the heat, just that there are differences that are important to identify that may impact policy implementation. We are currently collecting data to assess the impact of female sex hormones on adaptation and the influence of different types of contraceptives on environmental stress. This should help to ensure the policies we’re trying to inform are appropriate and representative for both male and female Warfighters.” said Giersch.

Researchers across all the divisions at USARIEM continue to conduct studies to better understand and optimize the female Warfighter, which will subsequently strengthen the DOD’s ability to create programs and policies around the female Warfighter’s performance and well-being.

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.