Bone stress injuries are injuries from overuse that typically result from repetitive, high-intensity, weight-bearing activities—and therefore may be preventable by risk factor modification.1 Compared to active component service members, BSIs are more common in military trainees.2 Basic Cadet Training, an annual 6-week summer program for individuals selected for enrollment at the U.S. Air Force Academy, Colorado, emphasizes physical and mental conditioning and profession of arms indoctrination.
Basic trainees with potential BSIs are managed in the physical therapy and sports medicine clinics according to an algorithm designed for military training environments.3 Plain film radiograph and magnetic resonance imaging are used for diagnostic confirmation.
A total of 3,331 trainees participated in U.S. Air Force Basic Cadet Training from 2022 through 2024. During the 3 training iterations during that period, 57 radiographically-confirmed BSIs occurred, in 1.7% of trainees. BSIs occurred in the lower leg (n=37; 64.9%), ankle (n=8; 14.0%), foot (n=7; 12.3%), and hip (n=5; 8.8%). Female trainees were over 3 times as likely to experience radiographically-confirmed BSIs than males (percent ratio: 3.35; 95% CI: 1.99, 5.64).
Radiographically-confirmed BSIs declined among both males and females during the surveillance period. While the percentage of cadets with radiologically-confirmed BSIs declined by 76.6% from 2022 to 2024, this descriptive study cannot attribute any particular countermeasure to this decline. Further investigation is warranted to assess the impacts of two countermeasures recommended by medical staff that were implemented in latter iterations, as described by the Basic Cadet Training Director of Operations (e-mail communication, Aug. 16, 2024). In 2023, and re-emphasized in 2024, the physical fitness program was modified to establish a more tightly standardized regimen featuring a gradual increase in intensity. Second, in 2024 basic trainees were provided more time to ‘break in’ their combat boots before their use in formation running.
Surveillance and work-up biases are unlikely, as medical access and clinical evaluation were unchanged during this period. Likewise, the preparatory fitness program detailed in the U.S. Air Force Academy Appointee Handbook did not change. These data suggest that modifications to the fitness training regimen may reduce BSIs during Basic Cadet Training at a military service academy.
Author Affiliations
U.S. Air Force Academy Physical Medicine Flight: Capt Hogan, Capt Prinster; U.S. Air Force Academy Sports Medicine: Maj Caulkins; U.S. Air Force Academy Human Performance Laboratory: Maj Deming; U.S. Air Force Academy Preventive Medicine: Lt Col Webber
Disclaimer
The views expressed in this research are those of the authors and do not necessarily reflect the official policy nor position of the Department of the Air Force, Department of Defense, or the U.S. Government.
References
- Knapik JJ, Sharp MA, Canham-Chervak M, Hauret K, Patton JF, Jones BH. Risk factors for training-related injuries among men and women in basic combat training. Med Sci Sports Exerc. 2001;33(6):946-954. doi:10.1097/00005768-200106000-00014
- Lee D, Armed Forces Health Surveillance Center. Stress fractures, active component, U.S. Armed Forces, 2004-2010. MSMR. 2011;18(5):8-11.
- Nye NS, Covey CJ, Sheldon L, et al. Improving diagnostic accuracy and efficiency of suspected bone stress injuries. Sports Health. 2016;8(3):278-283. doi:10.1177/1941738116635558