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Abstract
Movement, somatosensory, and neuromuscular function are theorized to be altered and directly relate to the heightened musculoskeletal injury risk following concussion, but to date, limited research exists. The purpose of this dissertation was to examine functional movement (gait and single-leg hop), somatosensory (passive joint repositioning, touch-sensation threshold, pressure-pain threshold), and neuromuscular (superimposed burst technique) function among concussed and healthy, matched-control cohorts acutely (0-7 days post-injury) and asymptomatic (± 72 hours of symptom resolution). Eight concussed and 8 controls completed all assessments across the two clinical timepoints. Concussed individual’s asymptomatic status (symptom severity ≤ 3) was determined by comparing daily symptom severity to their retrospective baseline proxy symptom severity, and controls were yoked to their matched counterpart. Gait occurred on an instrumented walkway with spatiotemporal outcomes calculated. Single-leg hop occurred in a motion capture space with kinematic and kinetic outcomes derived. Passive joint repositioning occurred on a Biodex, with absolute joint angles recorded. Touch sensation was assessed using standard Semmes-Weinstein monofilament procedures, and pressure-pain threshold assessed via algometry. The superimposed burst technique examined voluntary knee extensor torque production and maximum torque capability via supramaximal electrical stimulation. Mixed model ANOVAs were used to examine differences between groups over time among functional movement and somatosensory outcomes, and independent t-tests among neuromuscular outcomes (completed only at asymptomatic timepoint). Gait demonstrated slower and shorter spatiotemporal outcomes acutely for concussed individuals that resolved once asymptomatic. We observed subtle, but potentially important, joint moment differences during single-leg hop between groups. Touch sensation was significantly higher (i.e. more force needed to detect) among concussed individuals across both timepoints. No statistically different pressure-pain thresholds or joint repositioning joint angle errors were observed, though potentially important effect size magnitudes were identified. No statistically different voluntary knee extensor torque production or maximum torque capability were observed. The cumulative dissertation findings indicate potentially important biomechanical and somatosensory deficits following concussion, but not neuromuscular outcomes. These findings provide novel biomechanical, somatosensory, and neuromuscular insights for future research to utilize and optimize longitudinal investigations aimed at examining the heightened musculoskeletal injury risk after concussion phenomenon.