Asymmetrical Loading Patterns in Military Personnel With a History of Self-Reported Low Back Pain

Background: Servicemembers are required to operate at high levels despite experiencing common injuries such as chronic low back pain. Continuing high levels of activity while com-pensating for pain may increase the risk of musculoskeletal injuries. As such, the purpose of this project was to determine if servicemembers with chronic low back pain have reduced lower extremity performance, and if they use alternate strategies to complete a functional performance task as compared to healthy servicemembers. Methods: Of a total of 46 male United States Marine Corps Forces Special Operations Command (MARSOC) personnel, 23 individuals who suffered from chronic low back pain (age = 28.6 ± 4.4 years, weight = 84.2 ± 6.8 kg) and 23 healthy controls (age = 27.9 ± 3.8 years, weight = 83.8 ± 7.7 kg) completed a stop jump task. In this task, three-dimensional biomechanics were measured, and lower extremity and trunk strength were assessed. Results: The low back pain group exhibited higher vertical ground reaction force impulse on the dominant limb (0.26% body weight [BW]/s), compared to the nondominant limb (0.25% BW/s, p =.036). The control group demonstrated relationships between jump height and strength in both limbs (dominant: r = 0.436, p =.043; nondominant: r = 0.571, p =.006), whereas the low back pain group demonstrated relationships between jump height and dominant limb knee work (r = 0.470, p =.027) and ankle work (r = 0.447, p =.037). Conclusions: This study demonstrates that active-duty MARSOC personnel with a history of low back pain reach similar levels of jump height during a counter movement jump, as compared to those without a history of low back pain. However, the asymmetries displayed by the low back pain group suggest an alternate strategy to reach-ing similar jump heights as compared to healthy individuals.