By Samir Deshpande, Walter Reed Army Institute of Research
Soldiers, according to Army Chief of Staff Gen. James McConville, are the Army’s “most important weapons system.” Like with any other weapons system, preventive maintenance is necessary to ensure continuous readiness and maximum performance.
The Army’s Performance Triad is a public health campaign aiming to implement this upkeep through proper sleep, activity and nutrition, recognizing their critical role in developing the high-quality, physically fit, mentally tough Soldiers able to succeed during Multi-Domain Operations.
The current COVID-19 pandemic adds another layer of difficulty to continuously remaining fit and effective, requiring extra care to avoid infection or spreading the infection to family, friends, fellow Soldiers and the wider community.
Yet, researchers from the U.S. Army Research Institute of Environmental Medicine and Walter Reed Army Institute of Research, both subordinate commands of the U.S. Army Medical Research and Development Command, are finding that these same building blocks of Soldier performance may also prove to be techniques for fighting off the disease.
“As we’ve shifted our resources to help address this pandemic, we’re building from the understanding that the same strategies that help us optimize human performance in training and operational settings—eating well, exercising right and getting a good night’s sleep—also protect us from infection,” said Col. Sean O’Neil, USARIEM’s Commander.
Here is what these laboratories, leaders of the Army’s efforts to improve military nutrition, human performance, sleep, resilience and defense against infectious disease, have learned and what they advise:
Nutrition: The Building Blocks of Immunity
A balanced diet that meets energy demands and provides essential nutrients not only increases energy and endurance, enabling better performance—it also directly impacts the immune system.
The absence of key nutrients can directly limit your body’s ability to protect from invaders: a lack of vitamin D can limit the production of antimicrobials and compromise your skin, the primary barrier against infectious disease; a lack of iron and zinc directly threaten the function of white blood cells, which include your body’s “first responders” against pathogens.
Poor nutrition can even increase harm from infectious disease—one study found that low levels of the nutrient selenium caused viral mutations resulting in an even more damaging infection.
Obesity, or excess energy intake, can also stress the immune system. Studies have identified a greater risk of hospital-acquired infections, more severe infections from influenza and other respiratory infections and a greater overall risk of viral and bacterial infection.
Furthermore, individuals with obesity are still at risk of missing critical nutrients from their diets, further compounding potential risk.
“These findings highlight the critical role of diet and nutrition in Warfighter health and performance—including immune function and infectious disease. Optimal nutrition is a critical first step to immunity,” says James McClung, chief of the Military Nutrition Division at USARIEM.
Sleep—Your Internal Body Armor
Given its well-known impact on vigilance, learning, reaction time and mental acuity, sleep loss has long been a topic of concern for military leaders and a focus of research by military scientists. Less widely known, however, is the recent evidence showing that sleep is also critical for maintaining a healthy and effective immune system.
It is now understood that sleep duration is a powerful predictor of infection. In one study, volunteers were exposed to the virus that causes the common cold. It was found that those who averaged less than seven hours of sleep per night had a three-fold greater risk of infection than those who averaged eight hours or more; for those who habitually obtained less than five hours of sleep, the risk was 4 ½ times greater.
In addition, limited but exciting evidence from animal studies suggesting that sleep not only helps protect against initial infection, but also plays a direct role in aiding recovery from infectious illness.
“These studies show that sleep can enable and enhance your body’s ability to establish physical, cognitive and now immunological dominance,” says Lt. Col. Vincent Capaldi, director of the Behavioral Biology Branch at WRAIR, responsible for studying the relationship between sleep and military performance.
Physical Activity: Boost Your Immune System
Physical activity and fitness are critical aspects of military service as well as overall health—they also can boost your immune system.
Even a single session of physical activity can improve your immune system, resulting in the redistribution of immune cells to your body’s “front lines”—places like your lungs or gut—to enhance surveillance of potential pathogens. Regular physical training also improves one’s immune response to infection challenges.
Conversely, excessive physical training without adequate time to recover has been linked to a suppressed immune system.
“Physical activity and fitness are key to optimal and enhanced health and performance of our Soldiers. Special care to practice smart physical training practices will help promote stronger immune system responses,” says Susan Proctor, chief of the Military Performance Division at USARIEM, responsible for targeted musculoskeletal health and military performance research.
Don’t Let This Information Stress You Out
In addition to emotional health, well-being and job performance, stress may impact our immune system as well.
One study found that self-reported stress predicted more symptoms in volunteers exposed to influenza virus. Another study found that individuals who reported high levels of stress over a period of at least a month were two to three times more likely to develop colds than those reporting less stress when challenged with a cold virus.
A range of evidence also suggests that in addition to increasing the risk of infection, stress also worsens outcomes: stress may increase the likelihood of disease becoming symptomatic (as opposed to having a mild, asymptomatic infection) or more active (some viruses like herpes can lay dormant after infection with symptoms recurring over time).
“Stress has significant direct and indirect impacts to both risk and severity of infection—alongside getting enough sleep and regular exercise, stress mitigation strategies like mindfulness can go a long way to improving overall wellness and staying healthy,” says Amy Adler, acting director of WRAIR’s Research Transition Office, which bridges the gulf between laboratory and field to get research advances into Army training.
The Performance Triad, Infection and COVID-19
Perhaps most significant is that deficits in each factor are separately linked to decreased vaccine efficacy. For example, being physically active heightens vaccine effectiveness compared to being sedentary. Also, hepatitis B vaccine efficacy was eight times lower in individuals with obesity than those at a healthy weight; individuals who slept fewer than six hours the night prior to vaccination against hepatitis B were less likely to have gained immunity six months later compared to those who had obtained more than seven hours of sleep.
Furthermore, nutrition, sleep, exercise and stress are all intrinsically linked—high levels of stress may result in difficulty falling asleep, poor diet or lack of motivation to exercise; overexertion is often linked with compromised nutrition and sleep disturbances—suggesting that addressing one factor can positively influence others.
“Sleep, activity and nutrition are all critical aspects of ready, resilient and healthy Soldiers and Family members—it is important that individuals and their families consider every one of them. Setting realistic, attainable, but ambitious goals can help you focus on your health during this pandemic while building your invisible body armor against infection,” said Col. Deydre Teyhen, WRAIR’s Commander.
Research laboratories under USAMRDC, including WRAIR, are working diligently on a range of solutions to detect, treat and prevent COVID-19, including a vaccine. As these efforts progress, the following resources can help you and your family improve their first lines of defense—the immune system: