Patients with shoulder pain often exhibit hyperactivity in the muscles surrounding the scapula. In particular, the pectoralis minor seems to be prone to hyperactivity or tension related to shoulder dysfunction. (Castelein et al. Manual Therapy 2016).
In case a patient with shoulder disorders shows a dysfunction in the scapular muscles, it is important to restore optimal muscle balance, activating the muscles that are weak, with simultaneous inhibition of the hyperactive muscles.
A few studies have been performed examining relative muscle activity of the several scapular muscles during commonly used exercises.
As an example, this table from the study of Castelein et al. JOSPT 2016 shows that adding external rotation to an elevation exercise increases middle and lower trapezius activity, but not pectoralis minor activity, this compared to elevation in the scapular plane (scaption).
In another study (Castelein et al. Man Ther 2016), it was shown that closed chain protraction (push-up movements) resulted in equal activity in pectoralis minor and serratus anterior compared to an open chain protraction (serratus punch) in which pectoralis minor activity was lower compared to serratus anterior activity. Therefore, in case of pectoralis minor hyperactivity, open chain protraction should be preferred over closed chain protraction.
In summary, based on the studies of Castelein et al. (JOSPT 2016, Man Ther), in case of hyperactivity of the pectoralis minor, we can recommend to add an external rotation component to an exercise, (Castelein et al. JOSPT 2016), and to avoid closed chain protraction exercises (Castelein et al. Man Ther 2016).
Written by: Ann Cools
Castelein B, Cagnie B, Parlevliet T, Cools A. Scapulothoracic muscle activity during elevation exercises measured with surface and fine wire EMG: A comparative study between patients with subacromial impingement syndrome and healthy controls. Man Ther. 2016 Jun;23:33-9. doi: 10.1016/j.math.2016.03.007.
Castelein B, Cagnie B, Parlevliet T, Cools A. Superficial and Deep Scapulothoracic Muscle Electromyographic Activity During Elevation Exercises in the Scapular Plane. J Orthop Sports Phys Ther. 2016 Mar;46(3):184-93. doi: 10.2519/jospt.2016.592.
Castelein B, Cagnie B, Parlevliet T, Cools A. Serratus anterior or pectoralis minor: Which muscle has the upper hand during protraction exercises? Man Ther. 2016 Apr;22:158-64. doi: 10.1016/j.math.2015.12.002