The Scapular Contribution to the Amplitude of Shoulder External Rotation on Throwing Athletes - Technologies for Medical Sciences - page 221

The Scapular Contribution to the Amplitude
of Shoulder External Rotation on Throwing
Athletes

Andrea Ribeiro, Augusto Gil Pascoal, and Nuno Morais

Abstract Traditional clinical testing of the shoulder ER imposes a fixed scapula
in order to assess the glenohumeral joint, despite the recognized importance of the
scapular mobility and stability on shoulder function. Here the scapular contribution
to the amplitude of humeral axial rotation (internal and external) was tested on
the dominant shoulder of two groups of 12 subjects, the thrower athletes and the
non-athletes group. The scapular 3D position recorded at the end-range of GH and
TH IR and ER rotations was compared across groups using a mixed-model two-
way ANOVA. At the end-range of humeral ER, throwers showed less GH and
TH amplitude and a scapula more in retraction. A positive correlation was found
between scapular spinal tilt and TH and GH angles at the end-range of ER. The
throwers group showed a scapula more in retraction in maximal external rotation of
the humerus, and less external rotation in active motion. On volleyball players, the
scapula assumed a position of posterior spinal tilt when the humerus was positioned
more in external rotation. No such correlation was found in the control group or the
handball players group, possibly due to sports adaptation.

1 Introduction

Overhead throwers are a population at risk of developing shoulder injuries. The
mechanics of the throwing action, where a ball is released or stroked at maxi-
mum speed when the hand is placed over the head, puts an enormous stress on

A. Ribeiro ( ) • A.G. Pascoal
CIPER - Neuromechanics of Human Movement Research Group,
Technical University of Lisbon, Lisbon, Portugal
e-mail: [e-mail] ; [e-mail]
N. Morais
Higher School of Health, University of Aveiro, Aveiro, Portugal
e-mail: [e-mail]