Effects of adding scapular stabilization exercises to a periscapular strengthening exercise program in patients with subacromial pain syndrome: a randomized controlled trial

Key points

1. 01Both groups improved shoulder function (SPADI-Br) and pain scores within groups over 16 weeks, but gains were equal
2. 02No significant Time x Group interaction was found for any primary or secondary outcome at 4, 8, or 16 weeks
3. 03Scapular positioning, range of motion, and muscle strength all showed similar improvements in both groups
4. 04The only near-notable difference was 3.8% greater upward scapular rotation at 90 degrees in the stabilization group at 16 weeks, which did not exceed the minimal detectable change
5. 05Both groups showed equivalent reductions in kinesiophobia and similar patient satisfaction scores

How it was conducted

Design

Randomized controlled trial with 4-, 8-, and 16-week follow-up

Participants

60 middle-aged adults with chronic non-traumatic subacromial pain syndrome (mean symptom duration approximately 28-29 months), recruited from an outpatient physiotherapy clinic in Brazil

Groups

Periscapular Strengthening Group (PSG, n=30): 8-week progressive resistance program; Scapular Stabilization Group (SSG, n=30): same strengthening program plus scapular stabilization exercises emphasizing retraction and depression with visual, verbal, and kinesthetic feedback

Primary outcome

Shoulder Pain and Disability Index - Brazilian version (SPADI-Br, 0-100, lower = better function)

Secondary outcomes

Numerical Pain Rating Scale, scapular position (inclinometer), shoulder ROM, muscle strength (hand-held dynamometer), kinesiophobia (TAMPA), global perceived effect, patient satisfaction (MEDRISK)

Sessions

PSG completed mean 22.2 (SD 2) sessions; SSG completed mean 22.4 (SD 1.7) sessions

What they found

• SPADI-Br at baseline: PSG 63.3 (SD 18.4) vs SSG 65.7 (SD 20.9); between-group difference -2.4 [95% CI -15.4 to 10.6], p=0.71
• SPADI-Br at 8 weeks: PSG 37.1 (SD 25.3) vs SSG 39.7 (SD 30); between-group difference -2.6 [95% CI -15.6 to 10.4], p=0.69
• SPADI-Br at 16 weeks: PSG 32.8 (SD 26) vs SSG 34.2 (SD 30); between-group difference -1.5 [95% CI -14.5 to 11.5], p=0.82
• Pain (NPRS) at 16 weeks: PSG 0.5 (SD 1.7) vs SSG 1.2 (SD 2.4); between-group difference -0.7 [95% CI -2.2 to 0.8], p=0.35
• Shoulder flexion ROM at 16 weeks: PSG 146.6 (SD 24.7) vs SSG 149.9 (SD 21.8) degrees; between-group difference -3.2 [95% CI -17.5 to 11], p=0.65
• Upward scapular rotation at 90 degrees humeral elevation at 16 weeks: PSG 16.8 (SD 8) vs SSG 20.6 (SD 6.6) degrees; between-group difference -3.8 [95% CI -8.9 to 1.2], p=0.35 (exceeded SEM but p not significant)
• Serratus anterior strength change 0-16 weeks: PSG 3.9 (SD 4.0) vs SSG 3.8 (SD 4.0) KgF; between-group difference 0.1 [95% CI -2 to 2.1], p=0.98
• Global Perceived Effect at 16 weeks: PSG 3.3 (SD 1.5) vs SSG 3.1 (SD 2); between-group difference 0.2 [95% CI -1.1 to 0.7], p=0.67

Limitations

• The treating therapist was not blinded to group allocation, which is inherent to exercise-based RCTs but introduces potential performance bias
• Psychosocial factors such as patient expectations of recovery and self-efficacy were not assessed, though these can influence shoulder pain outcomes
• Not all patients had imaging to confirm or exclude tendon pathology, and pain medication use during the intervention was not controlled
• The scapular stabilization exercises were performed in isolation without integration into functional upper limb tasks, which may have limited their neuromotor relevance

Why it matters

For patients

Patients with chronic shoulder impingement can expect meaningful pain relief and functional improvement from a general periscapular strengthening program, and paying extra attention to retracting and depressing the shoulder blade does not appear to speed up that recovery.

For clinicians

Adding isolated scapular stabilization drills emphasizing retraction and depression to a standard periscapular strengthening protocol provides no measurable additional clinical benefit, suggesting that progressive resistance loading of the periscapular muscles may be sufficient.

For readers

This well-controlled RCT challenges the common practice of supplementing shoulder strengthening with specific scapular repositioning exercises, and raises the question of whether task-integrated functional upper limb loading may be a more effective approach.