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Shared Neuromuscular Performance Traits in Military Personnel with Prior Concussion

EAGLE, SHAWN R.1; KONTOS, ANTHONY P.2; MI, QI1; FLANAGAN, SHAWN D.1; NINDL, BRADLEY C.1; BEALS, KIM1; CONNABOY, CHRIS1

Medicine & Science in Sports & Exercise: August 2019 - Volume 51 - Issue 8 - p 1619–1625
doi: 10.1249/MSS.0000000000001974
CLINICAL SCIENCES
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Concussions are common in military personnel and may result in increased risk of musculoskeletal injury. One plausible explanation for this risk could be that neuromotor deficiencies enhance injury risk after a concussion through altered muscular activation/contraction timing.

Purpose To compare military personnel with at least one concussion during the past 1 month to 2 yr (CONCUSSED) to military branch-matched, age-matched, and Special Operations Forces group–matched controls (CONTROL) on physiological, musculoskeletal, and biomechanical performance.

Methods A total of 48 (24 CONCUSSED, 24 CONTROL) male Air Force and Naval Special Warfare Operators age 19 to 34 yr participated in the study. Participants self-reported demographics/injury history and completed the following assessments: 1) physiological—body composition, anaerobic power and capacity, aerobic capacity and lactate threshold; 2) musculoskeletal—lower extremity isokinetic strength testing, including time to peak torque; and 3) biomechanical—single-leg jump and landing task, including landing kinematics of the hip, knee and ankle. A machine learning decision tree algorithm (C5.0) and one-way ANOVA were used to compare the two groups on these outcomes.

Results Despite nonsignificant differences using ANOVA, the C5.0 algorithm revealed CONCUSSED demonstrated quicker time to peak knee flexion angle during the single-leg landing task (≤0.170 s; CONCUSSED: n = 22 vs CONTROL: n = 14), longer time to peak torque in knee extension isokinetic strength testing (>500 ms; CONCUSSED: n = 18 vs CONTROL: n = 4) and larger knee flexion angle at initial contact (>7.7°; CONCUSSED: n = 18 vs CONTROL: n = 2).

Conclusion The findings supported the hypothesis that CONCUSSED military personnel would demonstrate altered neuromuscular control in landing strategies and muscular activation. Future research should assess prospectively neuromuscular changes after a concussion and determine if these changes increase risk of subsequent musculoskeletal injuries.

1Neuromuscular Research Laboratory/Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA; and

2UPMC Sports Medicine Concussion Program/Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA

Address for correspondence: Shawn R. Eagle, M. A. T., 3860 S. Water St, Pittsburgh, PA 15203; E-mail: seagle@pitt.edu.

Submitted for publication November 2018.

Accepted for publication February 2019.

Online date: March 6, 2019

© 2019 American College of Sports Medicine