Subacromial pain syndrome (SAPS) defined as pain of non-traumatic origin localized around the acromion, is a debilitating, common and often chronic condition. Among many proposed underlying causes of SAPS, hypoperfusion and hypoxic conditions in and around the tendons may be an intrinsic cause of SAPS.
To determine if adding high intensity aerobic interval training (HIIT) of the rotator cuff to usual care was feasible in SAPS, and improved shoulder endurance more than usual care alone. Additionally, to examine the influence on shoulder pain and disability and the response of tendinous microcirculation following HIIT.
21 subjects with chronic SAPS were randomized to two groups: Experimental group (EG,n=13) receiving HIIT in addition to treatment as usual, and control group (CG,n=8) receiving treatment as usual. Before and after 8 weeks of exercise therapy, endurance performance was assessed by an incremental abduction exercise of the arm to exhaustion (TTE). Pain and disability was assessed by the shoulder pain and disability index (SPADI). Contrast enhanced ultrasound (CEUS) of the m.supraspinatus and tendon was utilized to indicate tendon blood flow.
Endurance in the TTE-test improved by an estimated 233 seconds more on average in EG than in CG (p=0.001, 95%CI:102to363) (p<0.001). The SPADI score was reduced 22 points more on average in EG (p=0.017, 95%CI:-40to-5). The change from pre to post-test was significant in EG for both TTE-test and SPADI improvement (p<0.001). EG also experienced less pain during exercise after the intervention compared to CG (p<0.001). CEUS indicated an increase in tendinous blood flow in EG (p=0.019).
HIIT rotator cuff exercise appear to be a feasible intervention in SAPS, increasing endurance performance more than usual care alone.