Defense Date

6-6-2019

Graduation Date

Summer 8-10-2019

Availability

One-year Embargo

Submission Type

dissertation

Degree Name

PhD

Department

Rehabilitation Science

School

Rangos School of Health Sciences

Committee Chair

Jason S Scibek

Committee Member

Christopher R Carcia

Committee Member

Amy L Phelps

Keywords

overhead athlete, racket sport, shoulder, upper extremity, soft-tissue adaptation, bony adaptation, motion deficit, internal rotation deficit, strength ratio

Abstract

Purpose: This study aimed to develop an understanding of humeral retroversion (HRV) asymmetries in tennis players and its impact on physical and performance characteristics of the shoulder.Participants: Healthy tennis players were categorized into 3 groups: younger juniors (n=11, age=14.5±0.5 years), older juniors (n=12, age=17.1±0.9 years), and collegiate (n=16, age=19.6±1.2 years). Methods: HRV, internal rotation (IR), and external rotation (ER), total arc of motion (TAM), HRV-corrected IR (HRVcIR), and HRV-corrected ER (HRVcER) were measured and calculated bilaterally using a digital inclinometer and ultrasonography. Bilateral differences (Δ) were calculated (dominant minus nondominant) for HRV and ROM variables. Isometric ER:IR strength ratios were measured and calculated for the dominant limb using hand-held dynamometry. Paired-sample t-tests and one-way ANOVAs were used to analyze limb-to-limb and group comparisons. Pearson correlation coefficients were used to analyze relationships between HRV and both ROM and strength measures. Results: HRV was significantly greater in the dominant limb in the younger juniors (dominant 62.8°±9.1° vs nondominant 56.3°±6.8°, p=.039), older juniors (dominant 75.5°±11.2° vs nondominant 68.6°±14.2°, p=.043), and collegiate players (dominant 71.7°±8.5° vs nondominant 61.2°±6.9°, p=.001). Significantly less IR was observed in the dominant arms only in older juniors (dominant 36.9°±9.9° vs nondominant 46.3°±11.2°, ppr=‑0.531, p=.001), ERΔ (r=0.654, pr=0.332, p=.039), HRVcIRΔ (r=0.735, pr=‑0.330, p=.040). No relationships were observed between HRV adaptations and strength ratios. Conclusion: Tennis players demonstrate increased HRV in the dominant limb, and it appears that this adaptation may occur mostly before the age of 14. ROM asymmetries appear to be significantly influenced by HRV adaptations. Once HRV was accounted for, ROM asymmetries appeared to neutralize. These findings suggest that correcting ROM measures for HRV may provide a more accurate assessment of shoulder motion adaptations. Clinical Relevance: Considering that tennis players demonstrate asymmetries in HRV, clinicians should be cautious when screening for and implementing interventions for soft tissue motion deficits based on clinical ROM measures.

Language

English

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