Affiliations: [a] College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| [b] Physical Therapy, Midwestern University, Glendale, AZ, USA
| [c] Clinical and Translational Science Institute, University of Rochester, Rochester, NY, USA
| [d] Phoenix Veterans Affairs Medical Center, Phoenix, AZ, USA
| [e] Biomedical Engineering, Pennsylvania State University, University Park, PA, USA
| [f] Physical Medicine and Rehabilitation, Penn State College of Medicine, Hershey, PA, USA
Correspondence:
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Address for correspondence: Meghan E. Vidt, PhD., Biomedical Engineering, Pennsylvania State University, 331 Chemical and Biomedical Engineering Building, University Park, PA 16802, USA. Tel.: +1 814 865 6885; E-mail: mzv130@psu.edu.
Abstract: BACKGROUND: Individuals fluent in sign language (signers) born to non-signing, non-deaf parents (non-natives) may have a greater injury risk than signers born to signing, deaf parents (natives). A comprehensive analysis of movement while signing in natives and non-natives has not been completed and could provide insight into the greater injury prevalence of non-natives. OBJECTIVE: The objective of this study was to determine differences in upper extremity biomechanics between non-natives and natives. METHODS: Strength, ‘micro’ rests, muscle activation, ballistic signing, joint angle, and work envelope were captured across groups. RESULTS: Non-natives had fewer rests (p = 0.002) and greater activation (p = 0.008) in non-dominant upper trapezius. For ballistic signing, natives had greater anterior-posterior jerk (p = 0.033) and for joint angle, natives demonstrated greater wrist flexion-extension range of motion (p = 0.040). Natives also demonstrated greater maximum medial-lateral (p = 0.015), and greater minimum medial-lateral (p = 0.019) and superior-inferior (p = 0.027) positions. CONCLUSIONS: We observed that natives presented with more rests and less activation, but greater ballistic tendencies, joint angle, and envelope compared to non-natives. Additional work should explore potential links between these outcomes and injury risk in signers.
