Superficial and Deep Scapulothoracic Muscle Electromyographic Activity During Elevation Exercises in the Scapular Plane.

STUDY DESIGN

Controlled laboratory study.

BACKGROUND

In scapular rehabilitation training, exercises that include a humeral elevation component in the scapular plane are commonly implemented. While performing humeral elevation, the scapula plays an important role, as it has to create a stable basis for the glenohumeral joint. However, a comparison of both deep and superficial muscle activity of the scapula between different types of elevation exercises is lacking and would be helpful for the clinician in choosing exercises.

OBJECTIVES

To evaluate scapulothoracic muscle activity during different types of elevation exercises in the scapular plane.

METHODS

Scapulothoracic muscle activity was measured in 21 healthy subjects, using fine-wire electromyography in the levator scapulae, pectoralis minor, and rhomboid major muscles and surface electromyography in the upper trapezius, middle trapezius, lower trapezius, and serratus anterior muscles. Measurements were conducted while the participants performed the following elevation tasks in the scapular plane: scaption (elevation in the scapular plane), towel wall slide, and elevation with external rotation (Thera-Band). The exercises were performed without and with additional load. Possible differences between the exercises and the load were studied with a linear mixed model.

RESULTS

Performing elevation in the scapular plane with an external-rotation component resulted in higher middle trapezius and lower trapezius activity compared to the scaption and wall slide exercises. The upper trapezius was maximally activated during scaption. The pectoralis minor and serratus anterior showed the highest activity during the towel wall slide. The towel wall slide activated the retractors to a lesser degree (middle trapezius, lower trapezius, levator scapulae, rhomboid major). Adding load resulted in higher muscle activity in all muscles, with some muscles showing a different activation pattern between the elevation exercises, depending on the load condition.

CONCLUSION

Scaption maximally activated the upper trapezius. The addition of an extra external-rotation component may be used when the goal is to activate the lower trapezius and middle trapezius. The towel wall slide exercise was found to increase pectoralis minor activity. Adding load resulted in higher muscle activity. Some muscles showed a different activation pattern between the elevation exercises, depending on the loading condition. The findings of this study give information about which elevation exercises a clinician can choose when the aim is to facilitate specific muscle scapulothoracic activity.