OCTOBER 13, 2022 – The Department of Defense requires U.S. active-duty service members to maintain overall physical fitness to ensure readiness. Components of physical fitness include cardiopulmonary endurance (also known as aerobic fitness), muscle strength, muscle endurance, body composition, and flexibility.
Two of the more common physical training activities to improve Soldier fitness are running and weight training.
The U.S. Army, as well as many physically-demanding civilian occupations, such as firefighters and police, use timed runs as a means to monitor the aerobic fitness of employees.
Though the U.S. Army has recently updated its fitness test, it continues to use the two-mile timed run to measure Soldiers’ aerobic fitness.
Running is a great way to maintain or improve aerobic fitness – but too much can cause injury.
The 2021 Health of the Force report (page 37), shows that running remains the leading activity associated with Soldiers’ medical limited duty profiles. Common running-related injuries include strains, sprains, stress fractures, and generalized pain with swelling to knees, lower legs, ankles, and feet.
“Most of these running-related injuries are due to cumulative microtrauma, or overuse,” says Tyson Grier, a U.S. Army Public Health Center kinesiologist who studies Soldier physical performance and injury data.
“When a Soldier is placed on a limited-duty profile, that Soldier is restricted from performing some or all of their physically demanding training and duties – typically for several weeks,” says Keith Hauret, a retired Army physical therapist working at the APHC. “So the effort to be physically fit solely by running can really backfire.”
Hauret explains that APHC data have consistently shown that excessive strain on the lower legs from running – often in combination with long road marches – is a common cause of training-related injuries.
These training-related injuries may also contribute to future injury-related conditions such as degenerative arthritis. Though chronic health conditions are rare in the relatively young active-duty Army population, the 2021 HoF report (page 67) shows that arthritis continues to be the most prevalent of the chronic conditions monitored.
To avoid overuse injuries affecting musculoskeletal structures such as muscles, tendons, joints, and bones, as well as potential long-term injury related conditions, both Grier and Hauret recommend a mix of training activities including weight-training and activities that increase speed, balance, agility, and flexibility.
Change the types of activities, challenge different sets of muscles, bones, and joints on different days, and include a weekly “day of rest” – as highlighted in the APHC’s current Soldier-Athlete Performance Triad’s activity goals.
Incorporating weight training into a running-centric exercise regimen will help promote joint and bone health – but again, too much can cause injury.
An investigative study led by Grier found that the frequency and intensity of weight-training are increasing among Soldiers, presumably in preparation for the new Army Combat Fitness Test. Grier has also shown that the greater amount of time spent in weight training, the higher the risk of sustaining a weight-training injury. Specifically, among the Soldiers in the study, injury risk doubled when weight training exceeded 1.5 to 2.5 hours a week. The most common injuries were to the shoulder, lower back, and knee. As with running, moderation is key.
Ultimately, weight training should not replace endurance running but should be included in a variety of exercises and drills in Soldiers’ weekly training programs to reduce injury risk while improving joint and bone health, and physical capacity.
Updated in 2020, Field Manual 7-22, Holistic Health and Fitness, and Army Techniques and Procedures 7-22.02, Holistic Health and Fitness Drills and Exercises, provide detailed guidance on the Army’s physical training program.
Information regarding the Army’s monitoring of injuries among Soldiers, along with studies of injury causes, risk factors, and means to prevent injuries associated with military activities, is provided through the APHC.
The U.S. Army Public Health Center focuses on promoting healthy people, communities, animals, and workplaces through the prevention of disease, injury, and disability of Soldiers, retirees, family members, veterans, Army civilian employees, and animals through population-based monitoring, investigations, and technical consultations.
NOTE: The mention of any non-federal entity and/or its products is for informational purposes only, and not to be construed or interpreted, in any manner, as federal endorsement of that non-federal entity or its products.
By V. Hauschild, MPH, U.S. Army Public Health Center