The effects of a six week scapular muscle exercise programme on the muscle activity of the scapular rotators in tennis players with shoulder impingement—A pilot study
Shoulder impingement is a common pathology in overhead athletes. Scapular dysfunction is regularly implicated in the pathogenesis of shoulder impingement and research has demonstrated altered scapular muscle activity in subjects with impingement. Clinically scapular movements are assessed and if they are found to be altered an exercise programme aimed at re-educating the scapular rotator muscles is often undertaken. However, to date there is no empirical research evidence to support the use of this type of exercise programme.
Objectives
To investigate the effect of a 6 week scapular muscle exercise programme on the muscle activity of lower trapezius, upper trapezius and serratus anterior.
Method
A test–retest design was used. Subjects were tested at the start, 3 weeks later without any intervention and then 6 weeks later having completed a scapular exercise programme. All subjects were tennis players with signs of shoulder impingement that were confirmed with either or both a positive “empty can” or Hawkins and Kennedy impingement test. Surface electromyography was used to recode the muscle activity of lower trapezius, upper trapezius, serratus anterior and anterior fibres of deltoid.
Results
During the control period there was no statistical difference in the average muscle activity, variability of the muscle activity and the onset times of lower trapezius, upper trapezius and serratus anterior. Following completion of the exercise programme there was no statistical differences found for the average muscle activity or muscle onset times. The exercise programme statistically reduced the variability of lower trapezius activity but not the other muscles ().
Discussion
This study suggests that a 6 week scapular exercise programme does alter the muscle activity of lower trapezius and has some potential clinical benefits. Future studies are needed that address the methodological limitations of this study and address if these changes in muscle activity have any clinical significance.
