Three-Dimensional Scapular and Clavicular Kinematics and Scapular Muscle Activity During Retraction Exercises

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To describe and compare scapular and clavicular kinematics and muscle activity during 6 retraction exercises in young healthy adults (mean +/- SD age, 23.2 +/- 2.4 years). BACKGROUND: Based on the association between shoulder injuries and scapular/clavicular movement, muscle activity during various exercises that target muscles surrounding the scapula have been investigated. However, the scapular and clavicular movements occurring during these exercises remain uninvestigated. Evaluation of the scapular and clavicular kinematics in addition to muscle activity provides additional information that allow clinicians to select exercises that best meet the patient's needs. METHODS: Three-dimensional scapular and clavicular kinematics and scapular muscle activity data were collected while the participants performed 6 scapular retraction exercises. One-way repeated-measures ANOVA and post hoc analyses were used to determine differences in scapular/clavicular kinematics and activation levels of the upper, middle, and lower trapezius and serratus anterior muscles occurring during the exercises. RESULTS: The general pattern of the kinematics observed during all retraction exercises was scapolar external rotation, scapular upward rotation, scapular posterior tilting, clavicular retraction, and clavicular depression. However, the exercises resulted in varying amounts of scapular movement and muscle activity. CONCLUSION: Clinicians can select appropriate exercises for their patients based on their need to strengthen specific retractor muscles and to improve specific scapular and clavicular movement patterns, pre-existing conditions, and available range of motion. J Orthop Sports Phys Ther 2010;40(3):169-179. doi:10.2519/jospt.2010.3018