Scapula Adaption in Overhead Athletes

Previous studies have proposed various ways to assess scapular dyskinesis, but they were impractical in clinical setting or the validity was questioned. The novel scapulometer we developed can measure the prominence of scapular medial border and inferior angle. We would like to examine its reliability and validity in subjects with symptomatic scapular dyskinesis. The long-term, high-intensity, unilateral loading may cause overhead athletes to develop adaptive changes in shoulder kinematics, range of motion (ROM) and strength in the dominant arm. We hypothesized that these changes may be related to scapular dyskinesis. According to the previous studies, we expect electromyography (EMG) biofeedback training can help improve the ratio of muscle activation of scapular muscle.

Fifty subjects of scapular dyskinesis will be classified and recruited from overhead players (baseball, basketball, tennis, volleyball, and so on) at high schools and through local Internet media. All participants and their legal guardians will provide written informed assent and consent, respectively, and the study will be approved by the Ethics Committee Institutional Review Board. Since intervention may be specific to pattern of scapular dyskinesis, pattern of scapular dyskinesis in control group will match the pattern of scapular dyskinesis in the intervention group. Twenty-five subjects per group is based on a minimal revenant difference of a self-reported functional questionnaire between intervention and control (Struyf et al., 2013; Andersen et al., 2014). Participants will be recognized as elite players in their age categories. Subjects will be excluded if they have a history of shoulder pain or injury. Players will supply their player characteristics, including years of sports practice, weekly sports and conditioning exposure and type of sports. Players' standing height, sitting height, and body mass will be measured and used with the chronologic age to estimate their biological age according to the assessments of skeletal age, dental age, and secondary sex characteristics (Baxter et al., 2005). A clinical trial with a blinded assessor will be conducted. The subject takes a form (with a letter A or B) indicating allocation to either groups (scapula-focused approach versus control) from a closed envelop. For the scapula-approached group, pattern of scapular dyskinesis will be assessed. Then subjects in B control group will meet pattern-matched criteria related to pattern assessment of scapula-focused group. More subjects may be recruited for the control group to meet pattern-matched criteria of scapula-approached group. A list with subject numbers and the group allocation that results from this matched-control procedure will be stored in a sealed envelope. Only the therapist has direct access to the allocation list. In this way, subjects are allocated to either intervention or control group comprised of 25 subjects in each group. Both groups will be treated by the same therapist.

Eligibility Criteria:
Inclusion Criteria:

* (1) with scapular dyskinesis
* (2) overhead players (baseball, basketball, tennis, volleyball, and so on) at high schools

Exclusion Criteria:

* if they have a history of shoulder pain or injury