Human performance optimization aims to take Soldiers to higher and higher peaks of physical and mental fitness.Let's flash back to the U.S. military in 2006.The U.S. had been engaged in Operation Enduring Freedom and Operation Iraqi Freedom for five and three years, respectively. In a post-9/11 environment with a higher operations tempo and longer and more frequent deployments, the U.S. military had an ongoing need to enhance mental and physical resilience and decrease injuries among deployed service members.In June of that same year, the Uniformed Services University of the Health Sciences hosted a conference titled "Human Performance Optimization in the Department of Defense: Charting a Course for the Future," with the goal of developing a strategic plan for human performance optimization (HPO). That conference marked DOD's acknowledgment of the importance of promoting warrior wellness and modernizing, training and structuring the force by leveraging cutting-edge science and technology (S&T) that would optimize the performance of servicemen and women in all stages of their careers. Such an approach would set the conditions for a more lethal force by ensuring that warfighters would be ready to respond to present and future threats. The conference was when the HPO effort officially emerged.Flash forward to 2017, when knowledge and technologies to enhance and sustain warfighters' health, well-being and performance as part of the HPO effort continued to evolve. DOD now considers HPO fundamental to accomplishing the military's mission. For the U.S. Army Research Institute of Environmental Medicine (USARIEM), HPO is a newer, shorter term to describe the research that the small Army medical lab in Natick, Massachusetts, has been doing for more than 50 years.CONTINUOUS OPTIMIZATIONThe USARIEM team prioritizes Army readiness by engaging in essential medical research focused on optimizing servicemen and women's health and performance during training and on the battlefield. "USARIEM partners with DOD, other federal entities, universities, nonprofits and industry stakeholders extensively to answer military-relevant questions and optimize Soldiers' health, resilience and performance," said Col. Raymond Phua, commander of USARIEM.USARIEM's location at Natick Soldier Systems Center, a 30-�minute drive west of Boston, puts the lab in close proximity to the extensive academic, federal and commercial knowledge and research assets of the Northeast corridor, giving researchers access to top potential collaborators. USARIEM is one of the very few labs in the world where all aspects of HPO come together.While the lab looks at HPO through a biomedical or a bioengineering lens, USARIEM's holistic approach to attaining an "optimized performance state," as Dr. Karl Friedl, USARIEM's senior research scientist for performance physiology described it, sets the lab apart. Friedl also explained that the unique and critical research capabilities that USARIEM provides to the DA, DOD and the nation are the synergy of subject matter expertise on performance, nutrition, environmental stressors and biomedical modeling from civilian researchers and Soldier scientists."The Army will always have Soldiers holding terrains in parts of the world that have extreme environments, and as long as we continue to encounter threats near and far, warfighters will always encounter risks," Friedl said. "This makes an optimized performance state sound like an elusive goal. While we cannot eliminate these risks, we can mitigate them."USARIEM is the only lab that has looked at all aspects of Soldiers' physical and cognitive performance, in terms of health, occupation and the environments they work in. We aim to sustain the health and fighting ability of warfighters by developing military medical doctrine and technology that will give war�fighters the ability to meet the physical and cognitive demands of any combat or duty position, accomplish the mission and continue to win present and future fights."USARIEM's internationally recognized research leaders are executing and supporting key products and strategic doctrine shifts, which include the U.S. Army Training and Doctrine Command (TRADOC) project to examine the knowledge, skills, abilities and other attributes associated with military occupational specialties (MOSs), as well as the Army surgeon general's 2020 strategy of shifting to a system of health through the areas of performance and nutrition, with the goal of attaining high-quality, longer lives free of preventable disease, disability, injury and premature death.Here are some of the emerging USARIEM technologies, medical doctrine and future research efforts to optimize warfighter health and performance in a variety of occupational environments and situations.EMERGING USARIEM TECHNOLOGIESThe Estimated Core Temperature (ECTemp) algorithm accurately estimates a Soldier's core body temperature simply by analyzing heart rate changes over time. Physiologically, heart rate reflects both the blood flow to the muscles and the rate of blood flow to the skin, containing information about both heat production and heat loss from the body. ECTemp can be incorporated into wearable technology, such as a chest harness with a physiological status monitor, which mission leaders and medics can monitor with a phone to detect if one or more Soldiers are at increased risk of heat illness. USARIEM developed ECTemp based on years of physiological data collected from multiple studies. By providing accurate core temperature information, the ECTemp can help military leaders make timely, critical training and mission decisions in hot, humid and unpredictable environments. The ECTemp has opened the door to future monitoring apps and wearable technology for the military.Unit leaders can use the Altitude Readiness Management System (ARMS), an Android-based app, to plan missions with appropriate expectations. By using data from more than 25 years of USARIEM's altitude studies, ARMS predicts how likely Soldiers are to experience acute mountain sickness during a mission, and how severely. ARMS also calculates how much time Soldiers need to complete missions and acclimate to a variety of altitudes. Unit leaders can use this easily accessible information to alter high-�altitude missions before deployment in order to prevent hypoxic events. The app is now fielded on the Nett Warrior platform and is being fielded through the �TRADOC online app store this year.The Soldier Water Estimation Tool (SWET) is an Android-based smartphone app and mission planning tool that can predict average water needs for groups of Soldiers for defined periods of time. The app uses a validated, updated sweat prediction equation based on five decades of USARIEM's research on sweat loss and hydration. A unit leader can plug in the temperature, humidity, cloud cover, type of clothing worn and Soldiers' workload. The app does the rest of the work. SWET supports the use of real-world planning in military settings in a variety of outdoor conditions. The app is now fielded on the Nett Warrior platform and, along with ARMS, is also being made available on the TRADOC app store this year.The Performance Readiness Bar (PRB) is a calcium- and vitamin D-fortified snack bar developed to optimize bone health in basic trainees. The snack bar was distributed at Fort Benning, Georgia, in the summer of 2017 and will be distributed at all four Army basic training locations in 2018. Calcium and vitamin D have already been proven to be necessary nutrients to improve bone health. However, USARIEM researchers' findings indicated that basic trainees needed higher-than-average amounts of calcium and vitamin D to support bone health during initial military training.According to the Military Health System, recruits often arrive at basic training with poor calcium and vitamin D status, making their bones more vulnerable to stress fractures and other injuries. PRB is one solution to this problem that will reduce attrition and personnel costs associated with initial military training, increasing Army readiness.The Occupational Physical Assessment Test (OPAT) was part of the TRADOC Soldier 2020 initiative, which would help set the standards necessary for Soldiers-male and female-to perform in combat MOSs. USARIEM researchers broke down those specialties into essential physical capabilities that a Soldier needs to be trainable for a given specialty.Throughout 2016, USARIEM researchers conducted more than 27 field studies in initial military training settings at Fort Benning, Georgia, Fort Leonard Wood, Missouri, and Fort Sill, Oklahoma, administering a robust battery of physical performance tasks and questionnaires before and after training. This effort resulted in the OPAT, which contains a battery of four tests: a standing long jump, a medicine ball throw, an incremental squat lift and an interval aerobic run. During this project, the USARIEM team validated the predictive ability of the OPAT to accurately place Soldiers into seven combat specialties.As a result of their efforts, the OPAT was fully implemented starting in 2017; it is now required for all Army candidates seeking to enter active, reserve or National Guard duty. The USARIEM team now is conducting a longitudinal study in which it is following volunteers for the next two years of their service to assess how successful they are in their assigned specialties after receiving their OPAT results. This data will provide the Army information on injury and dropout rates in basic training, showing how much time and money used to rehabilitate and recycle Soldiers could be saved.The Combat Rations Database (COMRAD) is an interactive, educational website that provides warfighters and military dietitians with information about military rations and the potential for affecting warfighters' diets and mission readiness. With COMRAD, warfighters and dietitians can view nutrition information for entire menus and even specific food components, like drinks and side dishes, in three types of rations: Meals, Ready to Eat; First Strike Ration; and Meal, Cold Weather/Long Range Patrol. COMRAD is based on a nutritional database created in collaboration with USARIEM's Military Nutrition Division. All nutritional information is accurate, and all menu components have been chemically analyzed, making COMRAD the go-to application for precise, easily accessible nutrition information on individual items, menus and daily food intake.FUTURE RESEARCH TO OPTIMIZE THE WARFIGHTERWarfighters engage in combat in all kinds of environments, including cold weather, such as in the Arctic. The question is: Are they prepared? USARIEM is conducting multiple research efforts, called Cold Weather Dexterity in Arctic Warfare, related to cold weather fighting protection. One of the biggest problems Soldiers can face is the loss of hand function and manual dexterity in the cold. This can happen when Soldiers do not wear gloves, causing the blood flow to the hands and fingers to decrease. Yet Soldiers can also experience reduced touch sensation and fine-motor dexterity by wearing gloves.Either scenario could prevent warfighters from using their weapons or other sophisticated equipment that is required for the mission. USARIEM is collaborating with U.S. Army Alaska and the U.S. Army Mountain Warfare School to research and develop technologies to increase warmth and blood flow to the fingers and face. This effort could optimize performance in Arctic missions while preventing frostbite and other cold weather injuries.Because of the unique multistressor environment of Army basic combat training, musculoskeletal injuries are common in recruits. The ARIEM Reduction in Musculoskeletal Injuries (ARMI) Study is a four-year research collaboration between USARIEM and the U.S. Army Public Health Center to develop evidence-based, actionable recommendations to Army leadership for strategies to reduce musculoskeletal injuries in basic combat training without reducing training standards. USARIEM researchers will be tracking 4,000 recruits throughout and for two years after basic combat training to identify risk factors and evaluate the effectiveness of ongoing musculoskeletal injury prevention and related initiatives.Bullets and rockets are not the only things servicemen and women contend with when they deploy. Often, gastrointestinal illnesses, like travelers' diarrhea, can decrease Soldiers' performance, prompting USARIEM's Nutrition Interventions. For the last few years, researchers from USARIEM and the Combat Feeding Directorate of the U.S. Army Natick Soldier Research, Development and Engineering Center (NSRDEC), an element of the U.S. Army Research, Development and Engineering Command (�RDECOM), have been working together to understand the complex relationship between our health and the tens of trillions of microorganisms-including at least 1,000 known species of bacteria-living in our intestines. USARIEM researchers have conducted a series of field studies, from Natick to Pikes Peak in Colorado to Norway to characterize how different military stressors affect the gut microbiome and impact war�fighter health. Some of these studies have shown that high altitudes, high physical stress and diet affect Soldiers' gut health. USARIEM researchers plan to start testing for dietary interventions based on the findings of these and future gut health studies.CONCLUSIONIn the perpetually changing world of U.S. military S&T, HPO is one of the newer terms and efforts. Yet USARIEM has been doing research on HPO for decades and will continue to do so. By tapping into civilian and military expertise in performance, nutrition, environmental stressors and modeling, as well as additional local and international partnerships with academic, federal and commercial knowledge and research assets, USARIEM has been able to generate knowledge, products and technologies that optimize the performance of servicemen and women throughout their careers.For more information, go to www.usariem.army.mil.DR. STEPHEN MUZA is the deputy director, science and technology, at USARIEM. He holds a Ph.D. in physiology and biophysics from the University of Kentucky, an M.S. in physiology and pharmacology from the University of North Dakota and a B.A. from Miami University. After seven years of active-duty service in the U.S. Air Force and the U.S. Army, he served in a civilian research physiologist position in 1991 and became USARIEM's Thermal and Mountain Medicine Division chief in 2012. He was appointed to his current post in September 2016. In addition to conducting numerous hypobaric chamber and Pikes Peak research studies, he has led biomedical expeditions to the base of Mount Everest, Nepal, and the summit of Mount Kilimanjaro, Tanzania. He is an international expert in environmental physiology and medicine with an emphasis in high-altitude medicine, and serves on many scientific panels, including those of the U.S. Army Medical Research and Materiel Command and the Defense Health Agency.MS. MALLORY ROUSSEL is a science writer for the Science Strategic Management Office of USARIEM and a research fellow in the Oak Ridge Institute of Science and Education program. She holds a B.A. in English from Boston University. She has written about diverse subjects, from anatomic avatars to mission planning technology and military nutrition interventions.This article is published in the January - March 2018 issue of Army AL&T magazine.