Progressive Resistance Training for Shoulder Impingement
Conservative management for people with shoulder impingement normally includes exercise therapy to strengthen the rotator cuff muscles as well as scapular stabilising muscles. Research has shown that exercise therapy can be just as effective as surgical intervention for the reduction of shoulder pain in people with shoulder impingement. The goal of exercise therapy is to increase the strength, endurance and/or muscular hypertrophy of the scapula stabilising and rotator cuff muscles. Control and progression of exercise variables including intensity, duration, frequency and load are crucial to achieve this. However, most clinical research studies in exercise for shoulder impingement vary widely in their prescription of exercise and do not closely control these exercise variables.
A recent research study looked at the benefits of a closely controlled progressive resistance training program for people diagnosed with sub-acromial shoulder impingement. Participants in this study were assigned to either a progressive resistance training (PRT) group or a control group which performed no exercise. Participants in the PRT group participated in exercise therapy to strengthen the muscles around the shoulder twice per week for 2 months. The exercise variables in this study were closely monitored and progressed over the 2 months to optimise increases in muscle hypertrophy, strength and endurance.
After the 2 month intervention, participants in the PRT group significantly decreased shoulder pain at rest and during movement as well as improvements in shoulder and upper limb function, where as the control group made no improvements. Participants in the PRT group also reported taking significantly less pain analgesics and NSAIDs compared to the control group at the completion of the 2 month intervention.
Whilst the benefits of exercise therapy for shoulder impingement have been previously shown, this study highlights the need for specific exercise prescription to optimise improvements in shoulder pain and function for people with shoulder impingement. When prescribing exercise for shoulder impingement, if the goal of the exercise therapy is to increase muscle hypertrophy, strength or endurance the intensity, frequency, duration and load should be closely monitored and progressed to achieve these goals, just as in any exercise program. Lombardi, I., Magri, A. G., Fleury, A. M., Da Silva, A. C., & Natour, J. (2008). Progressive resistance training in patients with shoulder impingement syndrome: a randomized controlled trial. Arthritis Care & Research, 59(5), 615-622.
Link to Article – http://onlinelibrary.wiley.com/doi/10.1002/art.23576/pdf
The shoulder complex is made up of the gleno-humeral (GH), acromio-clavicular (AC) and sterno-clavicular (SC) joints as well as the articulation between the scapula and the thorax. The GH is enclosed by a loose and shallow joint capsule which promotes a large range of movement at the cost of less joint stability. This lack of static joint stability means that the shoulder complex relies heavily on the rotator cuff muscles for dynamic joint stability as well as control of scapula-thoracic rhythm for optimal shoulder biomechanics and range of movement.
What is the Sub-Acromial Space?
The sub-acromial space refers to the space underneath the acromion of the scapula and the head of the humerus. The tendons of the supraspinatus and long head of biceps muscle pass through this joint space as well as the sub-acromial bursa.
What is Sub-Acromial Shoulder Impingement?
Sub-acromial shoulder impingement refers to the tendons of either or both of supraspinatus and long head of biceps getting compressed in the sub-acromial space. This compression causes irritation of the tendons and the sub-acromial bursa, causing inflammation and a reduction in the sub-acromial space, resulting in further shoulder impingement. This impingement usually occurs with overhead movements of the arm, resulting in pain around the tip of the shoulder and down the upper arm.
What Causes Sub-Acromial Shoulder Impingement?
Sub-acromial shoulder impingement can be caused by any one of the following factors including rotator cuff tears, GH joint instability, poor scapula-humeral rhythm, tight posterior shoulder capsule, AC joint or labral injuries, bone spurs and deficits in GH joint external rotation. These factors in isolation or in combination with each other cause a reduction in the sub-acromial space resulting in sub-acromial shoulder impingement.
Assessment and Treatment of Sub-Acromial Shoulder impingement
People with sub-acromial shoulder impingement will usually present with a positive “empty can” test. However it is important to differentiate between sub-acromial impingement and supraspinatus tears by then performing the empty can test with shoulder distraction. With distraction in the empty can test, pain should be reduced with sub-acromial impingement as the sub-acromial space is increased where as a supraspinatus tear will remain just as painful. It is crucial when assessing the shoulder to determine the cause of the reduction in the sub-acromial space leading to shoulder impingement. Once these factors have been determined, rehabilitation should focus on correcting any mechanical deficiencies that may be contributing to sub-acromial impingement such as poor scapula-humeral rhythm of lack of rotator cuff control.