Objectives: The objective was to compare low level laser therapy (LLLT) therapy versus low LLLT therapy in combination with an exercise or exercise only on pain, range of motion (ROM), functionality, and activity limitation in patients with subacromial impact syndrome.

Design: Randomized and placebo-controlled clinical trial.

Setting: The setting for the study was the Municipal Clinic of Barueri, São Paulo, Brazil.

Participants: 60 patients with subacromial impact syndrome were randomly assigned in three groups.

Interventions: Group I, experimental (n=21) treated with low level laser therapy and exercises; Group II, experimental (n=21) treated with exercises; and Group III, experimental (n=18) treated with low level laser therapy. Laser used were GaAs (904 nm, 60 mW), in continuous emission. The participants received application of laser three times or week for eight weeks, on 9 shoulder points (3 Joules/point) per session.

Main outcome measures: Visual Analogic Scale (VAS) score, Shoulder Pain and Disability Index (SPADI), goniometer, Modified-University of California at Los Angeles Shoulder Rating Scale (UCLA), recorded before and after treatment.

In the groups that received low level laser therapy (LLLT), energy was irradiated over three insertion points in the supraspinatus muscle region, three points on the bursa subacromial, and three points along the bicipital groove, at 3 Joules per point. Total dose per shoulder was 27 Joules per treatment, using a previously calibrated Irradia Class 3B (Stockholm, Sweden). Pen's semiconductor consisted of gallium arsenide with a wavelength of 904 nm, frequency of 700 Hz, average potency of 60 mW, peak potency of 20 W, pulse duration of 4.3 ms, and 50 seconds per point (0.5cm2 area). The parameters followed the recommendation of the World Association of Laser Therapy for subacromial impact syndrome.

The participants received application of laser three times or week for eight weeks.

The groups treated with exercise followed the same training program. Isotonic strengthening exercises were performed for the scapular pivot, scapula stabilizer, and humeral propellant muscle groups. Three sets of 15 repetitions of each isotonic strengthening exercise were performed. The isometric exercises were performed in ten sets of ten seconds each. Analytical stretching of each muscle group was performed at the beginning of the session for 30 seconds.

The participants performed the exercises three times a week for eight weeks.

Inclusion Criteria:

• Clinical diagnosis of subacromial impact syndrome
• Age range: 30-75 years
• Both genders

Exclusion Criteria:

• cancer,
• diabetes,
• symptomatic shoulder osteoarthritis,
• surgery or previous fractures in the humeral head of the shoulder,
• history of acute trauma, calcification of the articular rotator tendon,
• total tendon rupture,
• cervical myofascial syndrome,
• radicular pain,
• inflammatory rheumatic disease,
• neurological disorders,
• depressive syndrome
• use of antidepressants,
• use of anti-inflammatory medications
• use anxiolytics