Thoracic Spine and Shoulder Kinematics and Muscle Activation in Rock Climbers with Shoulder Pain

Background and Purpose: Rock climbing has been a popular sport in recent years. Rock climbing includes various open-chain and closed-chain arm movements. Overhead reaching and pull-up are the basic rock climbing elements heavily involving upper extremities. Different inclination of the wall and terrain also demand sufficient range of motion and strength of the trunk. Generally overhead reaching and arm elevation may have similar shoulder kinematics, including scapular upward rotation, posterior tilt and external rotation. Arm elevation usually is accompanied with thoracic extension and unilateral lateral flexion and rotation. During pull-up, the scapula rotates downward and externally and tilts anterior. The prevalence of shoulder injuries are about 17%, the second most common among rock climbing injuries. In the shoulder injuries, shoulder labrum lesions and shoulder impingement are the most common. Previous studies have shown that individuals with shoulder impingement syndrome have shown decreased upward and externally rotation during arm elevation, and have limited thoracic extension range of motion and greater kyphotic posture. However, a previous study found no difference in the scapular kinematics and scapular muscle activation during pull-up in rock climbers with shoulder pain and healthy climbers. The non-significant finding may be due to that the pure pull-up may not mimic climbing tasks, in which the shoulder and trunk need to adapt different inclination of the wall. Therefore, the purpose of this study is to investigate the kinematics and muscle activation of the thoracic spine and shoulder in rock climbers with shoulder pain during climbing tasks with different reaching angles. Methods: Thirty sport climbers with shoulder pain and 30 healthy climbers matched with gender, age, and dominant hand will be recruited in this study. Testing tasks will include arm elevation in the scapular plane, overhead reaching to the target 15° backward to the frontal plane, pull-up with overhead reaching forward and backward. Thoracic and shoulder kinematics will be collected using an electromagnetic tracking system. The upper trapezius, lower trapezius, serratus anterior, latissimus dorsi, and erector spinae were collected with surface electromyography (EMG). A two-way mixed ANOVA will be used to determine differences between groups in the kinematics and EMG measures at the different arm elevation angles for the testing tasks.