The effect of EMG biofeedback: a randomized controlled clinical trial in patients with shoulder pain

INTERVENTION: The intervention program was divided into two periods. The first period was a three‐week phase with instruction in different exercises with focus on LT and SA activation. The purpose was to (re)activate the muscles and thereby increase the subjects’ awareness of those muscles’ position and function. The purpose of the second period (a five‐week phase) was to transfer the awareness gained through the first phase into the performance of more functionally complicated exercises. Here, coactivation of the LT and SA in dynamic movements was emphasised in order to master exercises and succeed to the next. Standardised progression regimes according to the subjects’ individual pain levels were developed and followed in both first and second period. The subjects were supervised once a week by the same physiotherapist and instructed how to progress and to do the exercises with 2x10 repetitions once a day during the eight weeks of intervention. Also, stretching exercises and ergonomic instructions were given. All participants in this study received the same exercises. The only difference between the interventions applied to the intervention and control group was the provision of online visual feedback of muscle activity, shown horizontally (from left to right) on a monitor (biofeedback) visible for both the subject and instructing physiotherapist in the intervention group. The no‐EMG control group only received instructions from the physiotherapist based on quality of exercise and if needed, manual/tactile corrections. CONDITION: Subacromial impingement syndrome (SIS) ; Musculoskeletal Diseases ; Impingement syndrome of shoulder PRIMARY OUTCOME: Self‐reported pain assessed using a numeric rating scale (NRS) as part of a questionnaire filled out before commencing physical testing at baseline and follow‐up (week 0 and 8):; 1. “Pain now” measured on NRS (0‐10) at baseline and follow‐up testing; 2. “Pain within the last 24 hours” measured on NRS (0‐9) at baseline and follow‐up testing; 3. “Pain within the last 7 days” measured on NRS (0‐9) at baseline and follow‐up testing; Furthermore, the subjects were asked to register their daily pain level in a diary throughout the eight weeks of home exercise. This diary was used to measure the daily pain development (NRS 0‐10) and then to measure compliance, as the subjects would register the execution of their home exercises. SECONDARY OUTCOME: 1. Self‐reported shoulder‐scores obtained from questionnaires at baseline and follow‐up:; 1.1. Disability of the Arm, Shoulder and Hand questionnaire (DASH); 1.2. The Oxford Shoulder Score (OSS); 2. Muscle activity measured by surface electromyography (sEMG) signals from three muscles: upper trapezius (UT), lower trapezius (LT) and serratus anterior (SA). The measurements were carried out according to a standardized experimental procedure, containing a voluntary movement task (described in experimental procedure). During arm elevation, mean relative activity (percentage of maximal voluntary electric activity, %MVE) was measured and muscle activation ratios between the muscles (UT/LT and UT/SA) were calculated. Measured at baseline and follow‐up. INCLUSION CRITERIA: 1. At least 30 days with pain/discomfort in the shoulder/neck region within the last year 2. At least two or more positive impingement tests based on the Jobe, Neer; Hawkins and Apprehensions tests 3. 18‐65 years old