Residual Impact of Previous Injury on Musculoskeletal Characteristics in Special Forces Operators

Jeffrey J. Parr, Nicholas C. Clark, John P. Abt, Julie Y. Kresta, Karen A. Keenan, Shawn F. Kane, Scott M. Lephart

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Background: Musculoskeletal injuries are a significant burden to United States Army Special Operations Forces. The advanced tactical skill level and physical training required of Army Special Operators highlights the need to optimize musculoskeletal characteristics to reduce the likelihood of suffering a recurrent injury. Purpose: To identify the residual impact of previous injury on musculoskeletal characteristics. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Isokinetic strength of the knee, shoulder, and back and flexibility of the shoulder and hamstrings were assessed as part of a comprehensive human performance protocol, and self-reported musculoskeletal injury history was obtained. Subjects were stratified based on previous history of low back, knee, or shoulder injury, and within-group and between-group comparisons were made for musculoskeletal variables. Results: Knee injury analysis showed no significant strength or flexibility differences. Shoulder injury analysis found internal rotation strength of the healthy subjects (H) was significantly higher compared with injured (I) and uninjured (U) limbs of the injured group (H, 60.8 ± 11.5 percent body weight [%BW]; I, 54.5 ± 10.5 %BW; U, 55.5 ± 11.3 %BW) (P =.014 [H vs I] and P =.05 [H vs U]). The external rotation/internal rotation strength ratio was significantly lower in the healthy subjects compared with injured and uninjured limbs of the injured group (H, 0.653 ± 0.122; I, 0.724 ± 0.121; U, 0.724 ± 0.124) (P =.026 [H vs I] and P =.018 [H vs U]). Posterior shoulder tightness was significantly different between the injured and uninjured limb of the injured group (I, 111.6° ± 9.4°; U, 114.4° ± 9.3°; P =.008). The back injury analysis found no significant strength differences between the healthy and injured groups. Conclusion: Few physical differences existed between operators with prior knee or back injury. However, operators with a previous history of shoulder injury demonstrated significantly less shoulder strength than uninjured operators as well as decreased shoulder flexibility on the injured side. All operators, regardless of prior injury, must perform the same tasks; therefore, a targeted injury rehabilitation/human performance training specifically focused on internal rotation strength and tightness of the posterior capsule may help reduce the risk for recurrence of injury. Operators presenting with musculoskeletal asymmetries and/or insufficient strength ratios may be predisposed to musculoskeletal injury. Clinical Relevance: Specific fitness programs to compensate for deficiencies in strength and flexibility need to be designed that may reduce the risk of injuries in Special Forces Operators.

Original languageEnglish
JournalOrthopaedic Journal of Sports Medicine
Issue number11
StatePublished - Nov 13 2015

Bibliographical note

Funding Information:
One or more of the authors has reported the following potential conflict of interest or source of funding: This study was supported by the US Army Medical Research and Materiel Command #W81XWH-11-2-0020. Opinions, interpretations, conclusions, and recommendations are those of the authors and not necessarily endorsed by the Department of Defense, Department of the Army, or US Army Special Operations Command.

Publisher Copyright:
© 2015, © The Author(s) 2015.


  • injury prevention
  • military
  • muscle injury
  • performance
  • residual

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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