Proper muscle balance is essential in order to prevent injuries and to enhance athletic performance. Common sport-related injuries such as rotator cuff tendonitis or bicepital tendonitis are due to overuse/improper muscular balance. These injuries are common in certain sports, but are also common to the everyday wheelchair user.
A high percentage of athletes in throwing sports (baseball, shot put, discus, etc.) and other sports such as wheelchair track, swimming, and paddling report shoulder pain and/or injury and some studies estimate that up to 75% of manual wheelchair users will develop shoulder pain during their lifetime. The impact of a shoulder injury can be devastating for both the athlete and the wheelchair user impacting performance, functional mobility, and independence.
Etiology
Rotator cuff tears, degenerative changes, and other pathologies about the coracroacromial arch are commonly found in wheelchair users with symptomatic shoulder pain. These degenerative changes occur from repeated microtraumas when the joint space between the humeral head (upper arm) and the acromioclavicular (A/C) shelf decreases to the point where repeated contact occurs on the same area on the supraspinatus tendon. The position and the repetitive loading of the shoulder joint with use in sports and for propulsion most likely contribute to these changes.
Muscle Imbalances: Most rotator cuff injuries are due to muscle imbalances of the shoulder. Shoulder strength and muscular length/ROM imbalance can cause impingement of the soft tissue structures of the acromiohumeral space. Wheelchair users are even more susceptible to muscle imbalances. Nearly every motion and all repetitive motions are anterior working the pecs, shoulder internal rotators, anterior deltoid, etc. These anterior muscles become tight and shortened while the upper back muscles become weak and elongated. You can see these imbalances in the postures of chronic wheelchair users. A typical posture is rounded shoulders with mild thoracic kyphosis and forward head. This posture is even more accentuated by non-supportive wheelchair back that is stretched out accommodating this poor posture.
Preventative Strategies through Strength Training
Exercise Selection
It is important that athletes and wheelchair users perform stretches to the anterior musculature while strengthening the upper back, posterior shoulder, and scapular muscles.It is not uncommon for athletes to skip these muscle groups in favor of spending more time on strengthening the prime-movers specific to one’s sport or general fitness exercise. These include bench press and bicep curls.Performing exercises on the stomach or by being flexed forward in a wheelchair so that one can work the upper/lower trapezius, posterior deltoid, and rhomboids. A focus should also be on the external rotators of the shoulder. By restoring muscle balance, the acromiohumeral space can be preserved minimizing the pressure on the rotator cuff.
The upper trunk and shoulder girdle are the foundation of the upper extremities. With a solid foundation from which to move off of, the upper extremity (shoulder, elbow, wrist, hand) will show greater power, endurance, and efficiency as well as having a reduced chance of injury.
Order of Exercises
One strategy to promote muscular balance is the push-pull routine. After performing the bench press, follow up with compound rowing. By working the agonist and then by turning around and working the antagonist (the opposite muscle group(s)), you are assured not to overwork one muscle group and will increase strength in all of the movements possible at a joint.
Exercise Program Design
With use of the appropriate training load, the number of sets and repetitions govern the goal and outcome of the exercise program. Sets and repetitions can be set up for muscular endurance, muscular strength, and muscular power routines. Core muscles such as the scapular and pelvic girdle musculature are best trained via a muscular endurance routine. Other muscle groups can follow any of the above mentioned routines based on specific goals and activities required for sport or activities of daily living. Below is a table with general recommendations for the three routines.
The consequences of shoulder injury to the athlete and the wheelchair user can be devastating. Preventative measures can greatly assist in minimizing overuse injuries to the shoulder maintaining independence and enhancing performance.