Baseball Development: Creating Functional Scapula Control - Part 1

Thanks to the unilateral demands of the sport, baseball players are going to develop and present particular deficiencies compared to the general population. Research¹ has indicated that the throwing athlete’s scapula positioning and orientation differ compared to non-throwing athletes in the following areas: increased upward rotation, internal rotation and retraction . Internal rotation, retraction and other scapular movement indeed possess significant contributing factors to the throwing movement, but the focus of this week’s post will be scapular upward rotation. Myers et al.¹ discovered that, “the increased scapular upward rotation is a chronic adaptation to achieve the subacromial clearance needed during the throwing motion for improved throwing skill and possibly injury prevention.” To fully grasp this concept, a visual explanation is needed.

Described on the left is the location of the acromion and the humeral head. The acromion is part of the scapula, therefore, when the scapula moves so does the acromion. The area between the acromion and humeral head is what Myers et al. refer to as “subacromial clearance”. This area is going to be deceased if the humerus elevates and the scapula remains in its initial position. To maintain this clearance throughout the throwing motion, it is critical that the scapula upwardly rotates sufficiently. Research² has indicated that individuals with MDI (multidirectional instability) have a significant decrease in scapula upward rotation, compared to those individuals without MDI.   

A sufficient angle of scapular upward rotation is approximately 60 degrees (angle measured off of intersecting lines drawn up the spine and along the vertebral border of the scapula).³ A decreased angle will contribute to limited shoulder flexion and abduction. Especially in the baseball population, asymmetrical adaptation will be present as well.

 

 

During the game of baseball, shoulder flexion and abduction (overhead arm motion) is a movement that is unavoidable. This may seem redundant, but in order to play baseball, players do have to throw a ball. For the athletes that reveal similar limitations to the athlete above, the underestimated throwing motion quickly becomes quite taxing. Research¹ revealed that, “a loss of upward scapular rotation and resulting increased loss in acromial elevation perpetuate impingement of the subacromial structures.” In other words, limited upward rotation leads to unhappy shoulders, which equals a decrease in performance on the field. Hopefully, the seriousness toward limited scapula upward rotation has been elevated, and the evaluating process for this limitation will be performed more frequent and with greater caution. Stay tuned in next week for corrective exercises that can be incorporated into warm- ups, workouts and pre-throwing routines.

 

¹Myers, J. B., Laudner, K. G., Pasquale, M. R., Bradley, J. P. & Lephart, S. M. (2004). Scapular position and orientation in throwing athletes. American Journal of Sports Medicine, 33 (2), 263-271. http://www.pitt.edu/~neurolab/publications/2005/Articles/MyersJB_2005_AmJSportMed_Scapular%20Position%20and%20Orientation%20in%20Throwing%20Athletes.pdf

²Ogston, J. B. & Ludewig, P. M. (2007). Differences in 3-dimensional shoulder kinematics between persons with multidirectional instability and asymptomatic controls. American Journal of Sports Medicine, 35 (8), 1361-1370. http://ajs.sagepub.com/content/35/8/1361.full.pdf+html

³Cressey, E., Hartman, B., & Robertson, M. (2009). Assess & correct: Breaking Barriers to unlock performance. Indianapolis, IN: Indianapolis Fitness and Sports Training.

⁴Ludewig, P. M. & Reynolds, J. F. (2009). The association of scapular kinematics and glenohumeral joint pathologies. Journal of Orthopaedic & Sports Physical Therapy, 39 (2), 90-104.
http://www.jospt.org/doi/full/10.2519/jospt.2009.2808#.UwYZDvPnbct

⁵(2012, June 07). Ball and Socket Shoulder Joint [Web Photo]. Retrieved from http://www.jakegoh.com/ball-and-socket-joints-shoulder/