Shoulder Kinematics and Muscle Activation in Sport Climbers With Shoulder Pain

Sport climbing has recently become a highly popular sport and was included in the Summer Olympic Games 2021. Shoulder injury accounts for 15 to 20 percent of all sport climbing injuries, and it is the third most common problems, only surpassed by wrist and hand injuries. Sport climbing involves both open and closed chain movements of upper limbs. These prolonged and repetitive movements on vertical or overhanging terrain may lead to overuse and fatigue, which result in injuries. Sport climbing consists of multiple movement elements. Pull up with small holds is a basic movement in sport climbing, and activates many shoulder muscles, including trapezius, serratus anterior, latissimus dorsi. Studies related to sport climbing have focused on observing difference between sport climbers and non-sport climbers. Altered posture, increased scapulohumeral rhythm during arm elevation, and decreased shoulder angle during one-arm hanging have been observed in sport climbers. However, little studies have investigated whether climbers with shoulder injuries demonstrate different shoulder kinematics and muscle activation during tasks related to sport climbing. Therefore, the purpose of this study is to investigate the shoulder kinematics and muscle activation during pull-up with small holds in sport climbers with and without shoulder pain. Methods. Thirty sport climbers with shoulder pain and 30 healthy control subjects matched with gender, age, dominant hand and experience will be recruited in this study. All subjects will undertake physical examinations such as shoulder range of motion (ROM). Shoulder kinematics and muscle activation will be collected during arm elevation in the scapular plane and pull-up with gym-bar and 20mm depth small climbing holds. An electromagnetic tracking system will be used to measure bilateral scapular and humerothoracic kinematics. Surface electromyography (EMG) will be used to record muscle activation of bilateral upper trapezius, lower trapezius, serratus anterior and latissimus dorsi. Demographic data and physical examination will be analyzed by independent t test or Chi-square test. Two-way ANOVA will be used to test differences between groups in kinematics and EMG data at different phases of tasks. If significant interaction effect is found, Post-hoc pairwise comparison with Bonferroni correction will be used. The significant level is set at 0.05.