Activation of the Shoulder Musculature During Pendulum Exercises and Light Activities

Abstract

Study Design Prospective, single-group, repeated-measures design. Objectives To evaluate electromyographic (EMG) signal amplitude in the supraspinatus, infraspinatus, and deltoid muscles during pendulum exercises and light activities in a group of healthy subjects. Background There are numerous rehabilitation protocols used after rotator cuff repair. One of the most commonly used exercises in these protocols is the pendulum. Patients can easily perform these exercises incorrectly, and may also perform light activities of daily living without knowing that they may be putting excessive stress on the repair. The effect of improperly performed pendulum exercises and light activities after rotator cuff repair is unknown. Methods Muscle activity was recorded in 13 subjects performing pendulum exercises incorrectly and correctly in both large (51-cm) and small (20-cm) diameters, and while typing, drinking, and brushing their teeth. Results Incorrect and correct large pendulums and drinking elicited more than 15% maximum voluntary isometric contraction in the supraspinatus and infraspinatus. The supraspinatus EMG signal amplitude was greater during large, incorrectly performed pendulums than during those performed correctly. Both correct and incorrect large pendulums resulted in statistically higher muscle activity in the supraspinatus than the small pendulums. Conclusion Larger pendulums may require more force than is desirable early in rehabilitation after rotator cuff repair. J Orthop Sports Phys Ther 2010;40(4):230–237. doi:10.2519/jospt.2010.3095

The initial effects of a sustained glenohumeral postero-lateral glide during elevation on shoulder muscle activity: A repeated measures study on asymptomatic shoulders

“…Similar differences were reported for activities for daily living and shoulder exercises. For example, a previous study reported differences between typing and drinking tasks to be approximately 2% of MVIC for middle deltoid, and approximately 6% MVIC for infraspinatus muscle (Long et al , 2010). Another study reported differences of approximately 1% MVIC for supraspinatus muscle, when comparing the full and empty can exercises (Reinold et al , 2007).…”

Rotator cuff repair protocols: A survey of current New Zealand practice

“…As electromyographic (EMG) activity is low with these exercises, they were considered representative of passive exercise (Dockery, Wright, & LaStayo, 1998;Long et al, 2010;McCann, Wootten, Kadaba, & Bigliani, 1993). Active exercise was defined as "patient-generated movement" whereas resisted exercise was defined as movement undertaken with load applied (Petty, 2014).…”

“…Small pendular exercises (20cm in diameter) performed in a position of trunk flexion generate less than 10% maximal voluntary contraction (MVC) of supraspinatus, whereas large, incorrectly performed pendular exercises can generate more than 15% of MVC of supraspinatus (Long et al, 2010). The ASSET consensus statement recommends protected passive ROM during the first 6 weeks after rotator cuff repair of small to medium sized tears (< 4cm), with EMG activity of 15% (Thigpen et al, 2016).…”

Rotator cuff repair: post-operative rehabilitation concepts

“…Electromyographic (EMG) analysis of the supraspinatus confirms that therapist assisted shoulder elevation and external rotation, and pendulums performed by the patient are truly passive as these motions elicit activity similar to resting levels [21•]. However, EMG data reveals that with incorrectly performed pendulums moderate activity of the supraspinatus is generated and therefore may be avoided in early rehabilitation programs to minimize chance of patient error [22]. When correctly performing pendulums, the patients position themselves slightly bent over, supported with their non-surgical arm.…”