Studying Warfighters in Their “Natural Habitat”

Photo by Lance Cpl. Brandon Maldonado


By Regena Kowitz

When most people picture a scientist who specializes in medical research, the first thing that comes to mind is probably someone wearing a white lab coat working in a laboratory, surrounded by microscopes, test tubes, and gleaming countertops.

They probably don’t picture someone sitting on a dock, in the dark, bundled up against the cold night air, waiting for research subjects to surface from beneath the waves.

If you were watching Dr. Karen Kelly, research physiologist at the Naval Health Research Center (NHRC), in action, that’s exactly what you’d see because Kelly and her team, the Applied Translational Exercise and Metabolic Physiology team (ATEAM), specialize in field research. They take science to warfighters by adapting traditional laboratory practices to a field setting so ecologically valid data (i.e., data that can be generalized to real-world environments) can be collected.

When the ATEAM heads out to the field, they pack heavy duty cases with all the supplies and equipment they will need to do cognitive and strength testing and collect and store specimen samples in the field.

A typical day of doing research for Kelly, who is part of NHRC’s warfighter performance department, is anything but typical—her research subjects usually include elite warfighters and she goes to them to collect study data, whether they’re training under the water late at night or conducting field exercises in the blazing Southern California sun in the middle of the day.

At the heart of Kelly’s research is the study of hormonal and metabolic changes. These changes affect the health, readiness, and performance of warfighters, and can occur because of extreme conditions and stress. The information and samples collected in the field are analyzed by her team to measure hormone levels, which act as surrogate markers, letting Kelly know how well (or not) organ systems are functioning.

“We collect various biological samples—blood, saliva, and urine as well as physiological data—at different time points,” Kelly said. “This allows us to measure changes in hormonal response that indicate how well an individual is handling stress, recovering, responding to rest, or at what point the body is failing.”

Kelly’s portfolio includes studies that focus on mitigating musculoskeletal injuries, improving stress resilience, optimizing mental skills training, and enhancing human performance in extreme environments. That means her research subjects include military personnel who are most likely to experience those scenarios and challenges— infantry Marines and naval special warfare operators.

“Training and conducting missions in extreme environments, under challenging conditions, is the norm for special operators,” said Kelly. “These things can’t be replicated in a lab. To really understand the impact this has on warfighter physiology, and take into account all the variables you can’t reproduce in a lab such as environment and team dynamics, it’s important to collect ecologically valid data in the field—it’s a better reflection of what our warfighters actually experience in their daily training and it captures their true physiological status.”

By bringing science to warfighters, Kelly says she and her team can provide operationally relevant feedback to the operators and their leaders, while also adding to the scientific body of knowledge about human performance and injury prevention.

“I think the lab is really important for establishing baselines [and] proof-of-concept ideas, but one of the biggest gaps in our understanding of human performance is the field work,” said Kelly.

Kelly is no stranger to conducting research in the controlled environment of a lab. She has conducted clinical research in cardiovascular medicine, pathobiology, nutrition, bariatrics, endocrinology, and molecular medicine for the Cleveland Clinic. Collectively, Kelly has 18 years of research experience ranging from basic science to applied physiology.

“You can gather data in a very controlled environment but when you’re conducting research to improve warfighter performance and affect behavior change that supports that performance, you really need to understand the environment your subjects have to perform in,” Kelly said. “A subject who performs or behaves one way in the lab, may have a completely different experience in the real world when faced with all the variables you controlled for in the lab.”

When it comes to warfighters, particularly special operators, Kelly emphasizes that their training and mission environments are filled with variables—things that can’t be replicated in a controlled environment.

“When you’re working in the field, it’s dynamic,” said Kelly. “Equipment breaks, there are tides to account for, weather, terrain, and group dynamics. All of these factors can impact physical performance and physiology. If we only conducted research and collected data in the lab, we would be missing critical pieces of the puzzle.”

One of Kelly’s recent projects has been evaluating risk factors for musculoskeletal injuries in infantry Marines. Her goal is to identify optimal fitness levels and body composition that may reduce the risk of injury for personnel in physically demanding military occupational specialties.

For this study, Marine Corps Base Camp Pendleton is Kelly’s laboratory. The base, which is the Marine Corps’ largest on the West Coast, encompasses more than 125,000 acres of coastal and mountain terrain, from sandy beaches to dusty, scrub-covered hills.

Marines in this study are brought to NHRC’s warfighter performance lab prior to the onset of infantry training for a dual-energy x-ray absorptiometry of the whole body to measure bone density as well as body composition. She also captures high-resolution computerized tomography scans of each participant’s tibia. Kelly collects baseline data in the lab, but she and her team will collect the majority of data in the field.

Throughout the training cycle, Kelly monitors study volunteers for activity and hydration, body composition, and fitness. Her aim is to collect information on modifiable risk factors for injury and determine optimal fitness and body composition that may be protective against injury. By monitoring the Marines’ activity in the field, Kelly can determine the total weight they carry during training to understand how it affects their performance and health.

“The average weight carried by infantry Marines in their combat loads, plus their weapon, can average more than 95 pounds,” said Kelly. “The modern warfighter wears body armor with heavy protective plates, they carry mission-essential gear, food, and water—it all adds up. The more weight, the more impact on the musculoskeletal system, particularly the spine.”

Kelly and the ATEAM monitor platoons and collect data during hikes, land navigation, and other training exercises.

“With hiking, you can’t mimic all the terrain factors in a lab,” Kelly said. “You can replicate elevation but you can’t recreate all the surfaces and terrain that our Marines face, the slipping and sliding, and the uncontrolled tripping due to fatigue and terrain. We can do a controlled trip in the lab but there is a harness to catch the person due to necessary safety precautions required for human research. In the field, there are no safety harnesses.”

Kelly also points out that you miss out on the group dynamics in a lab, which is an important indicator of how people handle the stress of training. Military personnel do not typically work alone, especially infantry Marines. They train at the company level or they’re broken down into platoons and squads, but never alone.

“You can bring several subjects into the lab, but not an entire platoon,” said Kelly. “Testing someone in isolation versus actually having them in an operational environment with their teammates makes a difference—you see how they tolerate hard training, how individuals help teammates who struggle, and how, as a group, they manage challenges. I have yet to see a perfect training day.”

Understanding the physical and metabolic requirements of Navy SEAL Delivery Vehicle (SDV) operators is another project Kelly and the ATEAM are working on. This special class of SEALs has a unique training cycle which requires long periods of time underwater.

“This is one of the first studies to look at SDV operators during unit level training,” Kelly said. “They are unique in that they move horizontally in the water, not up and down in the water column like salvage divers. Their gear and equipment is different. Their mission is different. And the physiological impacts are also likely different. But we don’t know and that’s why we’re doing the research.”

This study is descriptive, meaning Kelly and her team are gathering baseline data to learn about the physical and physiological characteristics of this population as they go through training. According to Kelly, the goal is to characterize how their bodies are responding over time to the chronic exposure of the undersea environment where pressure and depth challenge the human body.

For this project, the lab and the lab hours are wherever and whenever the operators are doing their training. If Kelly needs to wait on a cold dock until after midnight to collect data from the operators, that’s what she does.

“The undersea piece is unique because you can’t really mimic the ocean in a lab very well,” said Kelly. “You can mimic the temperature but you can’t necessarily mimic the currents or ocean elements—things like water clarity or murkiness, sea life, kelp, and terrain—or the dynamics of the operators finning together in a controlled, simulated environment.”

Aside from currents and group dynamics, there are other variables that occur in real-world environments that don’t get accounted for in a lab.

“There have been several times when equipment issues have altered the training timeline and the duration of the training day and time spent underwater,” said Kelly. “More often than not, training goes longer than anticipated. The data we collect is not just about actual training, but also includes the time spent before and after, which can be up to 4-6 hours of additional work time for these guys. In a laboratory protocol, this time often doesn’t get accounted for.”

In a laboratory, Kelly pointed out, there always are protocols for safety and scientific merit, which are extremely important and vital to the protection of participants. But this is the inherent difference between a controlled environment and a real-time training environment where there is no way to control for everything that might happen. The data collected in the field may be a bit “dirty,” Kelly explains, but it has ecological validity and operational relevance because it reflects the actual demands placed on warfighters during training.

“In the real world, equipment breaks, gear malfunctions, currents change,” said Kelly. “We don’t want these things to happen in actual operations, but they sometimes do. Field research can help us answer questions about how these variables affect stress load or physiology and we can capture that data, do the science, and help our warfighters better prepare for what they’ll face on the battlefield.”

It’s important to note, added Kelly, that with field data, there are going to be some limitations.

“In the field, there are times when the operators get in and they have to clean their gear right away so there’s a little lag in collecting specimens, so we have to accept that margin of error,” she said. “In the field and real life, you’re not going to have a perfect sequence of events.” There also are several other benefits to collecting data out in the field—for warfighters and researchers.

“Field science is applied science, and it can be quick science,” said Kelly. “When we collect urine or do a finger stick checking for blood glucose, we can tell right away if someone isn’t hydrated or their blood sugar is low. We can give the warfighter immediate feedback about hydration levels or nutritional requirements—we can let them know they need to drink water or eat something.”

When working with the SDV operators, Kelly also works with their human performance specialists. In addition to providing individual feedback to the operators, Kelly shares information with their nutritionist and conditioning coach who can then develop a customized meal plan or strength training regime, based on scientific information, for each warfighter to help improve their performance.

For researchers, the benefits of being in the field also include building relationships with the warfighting community and creating opportunities for new avenues of research.

“When you’re in the field, you see the warfighters all the time, they get to know you,” Kelly said. “It makes science a little more personal and makes them aware of how science can impact their performance. When they understand why we’re doing research, that it’s to help them and their team, and that you are there to give back to them by collecting information that can inform leadership, they don’t mind volunteering.”

Kelly and her team may not be your typical lab coat- wearing researchers, and that’s a good thing. All types of science and research, from the lab to the field, are critical for understanding the needs of warfighters and the stress and sweat of field research isn’t for everyone.

“It is not for the faint of heart,” Kelly said. “The hours can be long and inconsistent. You have to do a lot of advanced preparation because when you’re in the field, you can’t just run next door and grab something you forgot. You are exposed to the elements—rain, snow, extreme heat, I’ve been through it all. But we improvise, we adapt, we overcome, we document, and we figure it out—these are the words we live by.”

About the author:

Regena Kowitz is a contractor for Naval Health Research Center public affairs.

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