Using Biofeedback for Shoulder Impingement

Shoulder impingement is one of the most frequent diagnoses given to those with shoulder pain. Individuals with shoulder impingement syndrome classically present with poor scapular muscle activation patterns and faulty mechanics when reaching or lifting the arm.(1) Going through a motor re-learning program is often necessary to restore proper movement patterning.(2) Given the lack of neuromuscular control that results from shoulder impingement, visual biofeedback is an obvious adjunct training tool to any rehabilitation program.

Literature Review

Before we look at the practical ways EMG biofeedback can be used for rehab of shoulder impingement, let’s take a glance at what the literature says. Numerous researchers and clinicians agree that shoulder impingement is the combined result of 1) tightness of the muscles in the front of the shoulder along with bad posture AND 2) faulty movement patterns caused by poor muscle timing/coordination of the scapular muscles.(1–4) We will mostly focus on the second issue.

Specifically, a study by Larsen et al looking at shoulder impingement found that using EMG biofeedback allowed participants with shoulder impingement to achieve proper muscle activation patterns.(5) In fact, the use of sEMG on those with shoulder impingement closely mimics the proper activation patterns seen in healthy subjects without shoulder impingement.(5)

With shoulder impingement, the infraspinatus muscle is often not being used optimally as a result of poor posture and muscle weakness. It is common to then see an increase in posterior deltoid muscle activity as a resultant compensatory pattern.(6) Lim et al found that sEMG biofeedback can be used to increase infraspinatus muscle activity and decrease posterior deltoid muscle activity during shoulder external rotation.(6) This creates better activation balance and control of the scapular muscles, limiting shoulder impingement symptoms.

Finally, Du et al found immediate improvements in scapular muscle activation patterns of the upper and lower traps after the use of electromyographical and video biofeedback for people with scapular dyskinesis as a result of shoulder impingement syndrome.(4)

Incorporating EMG Treatment

For the shoulder, surface EMG biofeedback offers real-time knowledge of performance and results during or immediately after the exercise. This is ideal for motor learning and its transfer to the activities and movement patterns we use so heavily in our daily lives.(2)

Shoulder impingement is caused by a lack of proper muscle activation patterns during simple movements.(3) Below are a few easy way to use sEMG biofeedback in the clinic to counter these improper recruitment patterns.

1. 1. Shoulder Scaption or Elevation (Single Channel)
      1. 1. Using a unilateral single channel, place the electrodes on the lower trap of the affected shoulder. (In video below, tape marks indicate electrode placement under the patient’s clothing)
         2. Instruct patient to perform shoulder elevation / scaption exercises.
         3. As the patient performs the exercise, they are instructed to increase activation of the lower traps; as a result the muscle activation meter should increase.

   2. Shoulder Scaption or Elevation (Dual Channel)
      1. Using dual channel mode, place one set of electrodes on the upper trap (CH1 in the video below) and the other set on the lower trap (CH2 in the video below) of the affected shoulder. (In video below, tape marks indicate electrode placement under the patient’s clothing)
      2. Instruct patient to perform shoulder elevation / scaption exercises.
      3. As the patient performs the exercise, they are instructed to keep upper trap activation low (CH1). The muscle activation meter should stay relatively still during the exercise. They are instructed to simultaneously increase activation of the lower traps (CH2); the muscle activation meter for this channel should increase.

          

         Channel 1 (left meter) is on the upper trap. Channel 2 (right meter) is on the lower trap.

   3. Shoulder External Rotation (Single Channel)
      1. 1. Using a unilateral single channel, place the electrodes on the infraspinatus of the affected shoulder. (In video below, tape marks indicate electrode placement under the patient’s clothing)
         2. Instruct patient to perform shoulder external rotation.
         3. As the patient performs the exercise, they are instructed to increase activation of the infraspinatus muscle; as a result the muscle activation meter should increase.

   4. Shoulder External Rotation (Dual Channel)
      a. Using dual channel mode, place one set of electrodes on the infraspinatus (CH1 below) and the other set on the posterior deltoid (CH2 below) of the affected side.
      b. Instruct patient to perform shoulder external rotation.
      c. As the patient performs the exercise, they are instructed to minimize activation of the posterior deltoid (CH2), resulting in minimal movement of the muscle activation meter. They are also instructed to increase activation of the infraspinatus (CH1) muscle resulting in an increase in the muscle activation meter for this channel.

Channel 1 (left meter) is on the infraspinatus. Channel 2 (right meter) is on the posterior deltoid. 

Summary

Recovering from shoulder impingement can be made easy with the use of mTrigger biofeedback. This surface EMG biofeedback device offers real-time knowledge of performance during and immediately after an exercise. Since shoulder impingement is frequently caused by a lack of proper muscle activation patterns during simple movements, this tool is ideal for motor learning and enhances the transfer of knowledge to the activities and movement patterns we use so heavily in our daily lives.

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References

1. Hotta GH, Queiroz POP, de Lemos TW, Rossi DM, Scatolin R de O, de Oliveira AS. Immediate effect of scapula-focused exercises performed with kinematic biofeedback on scapular kinematics in individuals with subacromial pain syndrome. Clin Biomech. 2018;58:7-13. doi:10.1016/J.CLINBIOMECH.2018.07.004
2. Antunes A, Filipe I, Cordeiro S, Rosa J, Carnide F, Matias R. Effectiveness of Three-Dimensional Kinematic Biofeedback on the Performance of Scapula-focused Exercises. doi:10.5220/0004928701730178
3. Cools AM, Declercq GA, Cambier DC, Mahieu NN, Witvrouw EE. Trapezius activity and intramuscular balance during isokinetic exercise in overhead athletes with impingement symptoms. Scand J Med Sci Sports. 2007;17(1):25-33. doi:10.1111/J.1600-0838.2006.00570.X
4. Du W-Y, Huang T-S, Chiu Y-C, et al. Single-Session Video and Electromyography Feedback in Overhead Athletes With Scapular Dyskinesis and Impingement Syndrome. J Athl Train. 2020;55(3):265. doi:10.4085/1062-6050-490-18
5. Larsen CM, Juul-Kristensen B, Olsen HB, Holtermann A, Søgaard K. Selective activation of intra-muscular compartments within the trapezius muscle in subjects with Subacromial Impingement Syndrome. A case-control study. J Electromyogr Kinesiol. 2014;24(1):58-64. doi:10.1016/J.JELEKIN.2013.09.008
6. Lim O, Kim J, Song S, Cynn H, Yi C. Effect of Selective Muscle Training Using Visual EMG Biofeedback on Infraspinatus and Posterior Deltoid. J Hum Kinet. 2014;44(1):83. doi:10.2478/HUKIN-2014-0113