Shoulder muscles with pendulum exercises and light activities during rotator cuff rehab
In repairing an injured rotator cuff, there are a number of potential rehab pathways, but most surgeons recommend that patients limit themselves exclusively to passive motion and restrict active motion in the arm to prevent another injury. Still, some studies report that 75% of patients with large tears who undergo repair go on to re-tear their rotator cuff, which means that proper rehab is of utmost importance. One exercise that's commonly recommended in rehab programs is the pendulum, in which patients gently and passively rotate their arm in circles using only trunk motion while leaning towards the ground. To the contrary, it's believed that many patients accidentally treat this as an active exercise and use shoulder muscles to perform it rather than keeping them relaxed, thus putting the repaired rotator cuff at more risk for re-injury. In addition, many recovering patients will attempt to return to activities of daily living (ADLs) like brushing teeth and typing without thinking them harmful, when in actuality, some of these can activate rotator cuff muscles and cause further complications. To better gauge how muscles are affected by carrying out pendulum exercises and ADLs after rotator cuff repair, a study was conducted that measured the EMG signal amplitude of muscles in the shoulder while performing these activities correctly versus incorrectly.
Thirteen subjects (7 male, 6 female) with an average age of 29 (range 20-57) were used for the study. Exclusion criteria were any history of shoulder pain, injury or surgery, use of assistive device for ambulation and inability to tolerate the study protocol. Electrodes were inserted on each patient's supraspinatus and infraspinatus muscles while they carried out the pendulum exercises and ADLs (typing, drinking out of a water bottle and brushing teeth) and numbers were recorded for EMG monitoring. Pendulum exercises were done on a diagram of 10-cm wide concentric circles that ranged from 20-51 cm, and patients were instructed to perform the exercises correctly (passively), then incorrectly (actively) in a small circle, then a large circle. The four exercises were completed in a randomized order and laser pointers were attached to each subject's arm to track the size of the circle. It was emphasized to subjects during correct exercises that it was more important for them to do the exercise passively then for the laser pointer to remain perfectly within the circle. Subjects were also instructed to stop exercises and start them over if they believed they were doing them actively.
Large pendulum exercises performed both incorrectly and correctly, as well as the activity of drinking from a water bottle all showed a mean peak percent MVIC (maximal voluntary isometric contraction) greater than 15% in the supraspinatus and infraspinatus muscles. Further analysis showed that the difference in percent MVIC in the supraspinatus between incorrect and correct pendulum exercises reached statistical significance only for large-diameter pendulums and not for smaller ones. It was also noted that drinking from a water bottle had significantly higher muscle activation than typing for both the supraspinatus and infraspinatus. The discrepancy in size of pendulum exercises may be explained by the fact that large pendulum exercises are more difficult than smaller ones, and thus cause the subject to perform them actively rather than passively. These findings suggest that large pendulums, regardless of how they're performed, and drinking out of a water bottle are activities that activate muscles in the shoulder directly involved in rotator cuff repair and should be restricted early on in recovery to prevent another injury. The study did note a few limitations, including the use of EMG as a measurement of muscle force, since it's not direct, and the use of healthy subjects rather than ones that had experienced a rotator cuff injury, as they may differ. Still, physical therapists and other health-care providers administering rehab should stress the importance of carrying out pendulum exercises correctly and guide patients in only performing activities that are safe for their shoulders. While typing and brushing teeth were deemed safe, activities as common and basic as drinking out of a water bottle can cause further injury and must be regulated early on in recovery. Finally, it's recommended that some patients use a support for their opposite arm when performing pendulum exercises to assist in executing them correctly.
-Summarized by Greg Gargiulo
-As reported in the April edition of the Journal of Orthopaedic & Sports Physical Therapy
