NATICK, Mass. (April 27, 2018) -- With the U.S. Army's dedicated focus on improving readiness and lethality of the present and future force, one of the biggest questions military leaders, training schools, medics and researchers face is this: How can the U.S. Army build more resilient warfighters who are resistant to musculoskeletal injury?

Imagine having the insight to determine which Soldiers are at the highest risk of injury, as well as having the medical guidance and tools to intervene before those Soldiers experience a career-ending injury. Researchers from the U.S. Army Research Institute of Environmental Medicine, or USARIEM, are striving to make this a reality as they embark on one of the largest research efforts they have conducted since the Physical Demands Study, a collaborative research effort between the Training and Doctrine Command Center of Initial Military Training, or TRADOC-CIMT, and USARIEM that led to the development of the Occupational Physical Assessment Test, or OPAT.

USARIEM researchers are collecting bone and muscle data from four thousand recruits as they go through BCT, and they are following the recruits during the first few years of their military careers. The data collection is part of a four-year longitudinal study, the ARIEM Reduction in Musculoskeletal Injury, or ARMI, study, an effort to better understand who is more likely to get injured and what can affect injury risk.

According to the principal investigators of the ARMI study, Dr. Julie Hughes and Dr. Stephen Foulis, two research physiologists from USARIEM's Military Performance Division, the primary goal of the ARMI study is to develop evidence-based, actionable recommendations to Army leadership to reduce musculoskeletal injuries in recruits without reducing training standards.

Stress fractures and other musculoskeletal injuries impact Army readiness by costing the Army lost duty time and millions of dollars per year. USARIEM has served as the center of excellence for warfighter performance science by generating evidence-based guidance on injury prevention through laboratory and field studies that resulted in developing the OPAT and the Performance Readiness Bar, or PRB, a calcium and vitamin D-fortified snack bar that helps strengthen bones.

"These prior studies have provided the foundation for us to undertake such a large field study," said Hughes, who specializes in studying bone injuries in Soldiers. "Musculoskeletal injuries are a real problem for the Army, especially for recruits. We realized that if we wanted to understand what factors contribute to musculoskeletal injuries and the physiology behind injury risk, we needed a comprehensive effort with a large sample size. The first step of this study is to determine the top four or five characteristics identifying those who are at greatest risk of injury so we can target them for intervention."

Dr. Foulis, a muscle physiologist who studies Soldier performance and played a large role in the data collection for the earlier OPAT studies, notes that muscles and bones work hand-in-hand during military training. Not only can muscles and bones get stronger during BCT, but they can also be vulnerable to injury.

"Stress fractures are not just a bone issue," Foulis said. "Muscles and bones interact together, so the novice Soldier is actually putting stress on the muscle and bone when they are performing exercises for which they are unaccustomed. Some evidence suggests that as the muscles start to fatigue, more stress is placed on the bone, which initiates a cycle that might lead to stress fracture."

The team of USARIEM-led researchers, from veterans in the trade to young researchers just beginning their scientific careers, are starting their study data collection at Fort Jackson, South Carolina. Foulis explained that not only is Fort Jackson large enough to accommodate such a large study, but many female recruits complete BCT at the installation. The researchers will later expand their data collection to other training installations, including Fort Benning, Georgia; Fort Sill, Oklahoma; and Fort Leonard Wood, Missouri.

During each data collection, researchers collected blood and urine samples from recruits at Fort Jackson during the first days of BCT. Later in the first week of training, the recruits came in shifts to complete various exercises, such as vertical jumps and balance testing, in order for researchers to assess muscle strength and flexibility.

The researchers also used a high-resolution bone and muscle scanner with the ability to examine muscles and bones with the resolution of 61 microns. According to Hughes, this is "less than the width of a human hair." With this state-of-the-art technology and through collaborations with top bone experts from Massachusetts General Hospital, USARIEM researchers are able to examine how bones and muscles change on a microstructural level during training.

"This is the right time to do the ARMI study because not only do we have the right people, but we also have the right technology," Hughes said. "We can use data from these high-resolution bone and muscle scans to not only study how bones break down, but also to examine how various factors, such as exercise and diet, lead to stronger bones and muscles."

Researchers from USARIEM have also teamed up with University of South Carolina researchers to collect surveys each weekend during the BCT period, asking recruits about their sleeping habits, nutrition, medications, socioeconomic status, past injuries and medical backgrounds. The surveys will also track if recruits are regularly consuming the PRB, which all Army BCT schools began distributing to recruits since the beginning of 2018, to evaluate whether the addition of the bar makes a difference in injury risk.

"We are working with USARIEM's Military Nutrition Division to track the recruits' calcium and vitamin D intakes, as well as whether or not they are consuming the PRB, to see if there is a contributing factor for their susceptibility for injury," Hughes said.

Even when recruits leave BCT, the data collection is far from over. The ARMI study team is also working with the Army Public Health Center in order to track injury information in study volunteers' medical files to see how Soldiers' careers progress after BCT.

"We are only hands-on during BCT," Foulis said. "We then follow them for two years after BCT to see who gets hurt and who does not. We want to see how those first few weeks of training in the Army affect the first few years of a Soldier's career."

Foulis and Hughes eventually plan to use these data to develop an algorithm that can target the recruits who are at highest risk of musculoskeletal injury.

"One of the objectives of the ARMI study is to detail those significant factors that could contribute to the likelihood of injury," Hughes said. "We will provide the TRADOC-CIMT evidence-based guidance to reduce injury risk without greatly modifying how recruits complete BCT."

"The goal is not to exclude anyone because of their risk of injury," Foulis said. "The goal is to figure out how to manage risk and find ways to intervene ahead of time."

The ARMI study team has already collected data from over three hundred recruits in the first eight months of the study, and as they expand their data collection to other training bases, they will continue to follow more recruits. While the end of the study is several years away, Foulis said that the ARMI study is structured to allow USARIEM researchers to answer certain questions and provide updates on a periodic basis throughout the study to allow the lab to optimize warfighter performance.

"USARIEM researchers have already made an Army-wide impact when it comes to studying how musculoskeletal injuries occur and how we can prevent them, but in order to improve the guidance and materiel-based solutions that already exist, there are many questions we have left to answer," Foulis said. "There are several interim points in the ARMI study where we can start to give answers to certain questions related to musculoskeletal injury. We have a study that allows us to answer many questions along the way.

"When we finish collecting data from all four thousand recruits, our ultimate goal is to use these data to provide guidance that will make a substantial impact on reducing injuries in our nation's warfighters."