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Injury Risk and Prevention of the Shoulder and Upper Arm

Common Injuries
Some common injuries of the shoulder are instability, rotator cuff tears, frozen shoulder, fracture, and arthritis. The category of injury known as instability can lead to a sprain or a dislocation where the head of the Humerus comes out of the glenohumoral socket. The rotator cuff is composed of four muscles; teres minor, infraspinatus, supraspinatus, and subscapularis. Its key function is as it sounds; rotation. A rotator cuff tear is when one or more of the four rotator muscles or their tendons is overused or strained to the point where it detaches from the insertion point on the scapula. Frozen shoulder is the result of an over-abundance of scar tissue in the joint, or a lack of use of the muscles for a long period of time. Movements become very painful. A fracture may occur to the bones of the shoulder joint; the clavicle, scapula, or humerus. Arthritis is common in middle aged patients, where smooth surfaces of cartilages are worn away and movement becomes painful.

Risks
The risk of shoulder injuries is very prevalent in athletes. One study tested anterior shoulder instability with a group of seven hundred fourteen young athletes of different sports. Results showed significant risk factors in this group Owens, B. D., Campbell, S. E., & Cameron, K. L. (2013, July). Risk Factors for Anterior  Glenohumeral Instability. The American Journal of Sports Medicine, 42(11), 2591-2596. doi:10.1177. Actions such as throwing, body to body contact and other unnatural motions contribute to these risks. ￼

A different study tested relationship between spinal alignment and shoulder range of motion in elder citizens. Results showed that increased kyphosis and weak back muscles may result in a decreased range of motion on the shoulders, which is then a risk of injury Imagama, S., Hasegawa, Y., Wakao, N., Hirano, K., Muramoto, A., & Ishiguro, N. (2014, July). Impact of spinal alignment and back muscle strength on shoulder range of motion in middle-aged and elderly people in a prospective cohort study.European Spine Journal, 23(7), 1414-1419. Retrieved from Academic Search Premiere. . Another significant risk of injury is having been previously injured, due to decreased stability of the joint. A study was conducted by Medical and Biological Engineering and Computing, using six subjects with previous shoulder injuries and six with no past injuries. Results showed a dramatic decrease in stability among those with previous injuries Marchi, J., Blana, D., & Chadwick, E. K. (2014, March). Glenohumeral stability during a hand-positioning task in previously injured shoulders. Medical and Biological Engineering and Computing, 52(3), 252-256. doi:10.1007/s11517-013-1087-9. Other than these few examples, there are several other risk factors associated with these injuries.

Prevention of Shoulder Injuries
Whether it is for athletics or everyday living, the best and most effective way to prevent injuries of the shoulders is to strengthen and stretch the rotator cuff muscles and deltoids, this will allow for an increased range of motion along with the ability to handle a heavier load Laudner, K. G., Metz, B., & Thomas, D. Q. (2013, February). Anterior Glenohumeral Laxity and Stiffness After a Shoulder-Strengthening Program in Collegiate Cheerleaders. Journal of Athletic Training, 48(1), 25-30. doi:10.4085/1062-6050-47.6.0 . Strengthening programs are common among athletes to prevent all types of injuries. One study in the Journal of Athletic Training tested the effectiveness of a shoulder strengthening program for cheerleaders. A strengthening program is a weekly workout plan with the goal of strengthening specific muscles or the whole body. This particular program consisted of workouts three times a week for the athletes. For the first four weeks, Mondays consisted of seated dumbbell shoulder presses, lateral pull-downs, and body weight dips. Wednesday’s workout contained incline barbell presses, seated rows, and standing cable reverse flies. On Fridays the athletes would do standing dumbbell military presses, incline dumbbell reverse flies, and push ups. For the 5th and 6th week, the workouts changed. Mondays consisted of flat-bench dumbbell presses, plate rows, and seated single-arm presses. Wednesdays the athletes would do incline dumbbell presses, single arm rows, and standing upright rows. And finally, Fridays they would do seated dumbbell presses, lateral pull-downs, and swiss ball dumbbell presses. Results showed those who participated in the program to have less Glenohumoral laxity Laudner, K. G., Metz, B., & Thomas, D. Q. (2013, February). Anterior Glenohumeral Laxity and Stiffness After a Shoulder-Strengthening Program in Collegiate Cheerleaders. Journal of Athletic Training, 48(1), 25-30. doi:10.4085/1062-6050-47.6.0 . ￼ When stretching the muscles and tendons of the shoulder and upper arm, there is risk of having incorrect form which could do more harm than good (Maraki et al., 2006). However properly stretching the rotator cuff has many benefits. Maraki et al. discussed the importance of arm positioning while stretching the infraspinatus, supraspinatus, and posterior deltoid. It was found that performing, correct rotator cuff stretches, with proper arm angles, is very effective in preventing injuries. Muraki, T., Aoki, M., Uchiyama, E., Murakami, G., & Miyamoto, S. (2006, June). The effect of arm position on stretching of the supraspinatus, infraspinatus, and posterior portion of deltoid muscles: A cadaveric study. Clinical Miomechanics, 21 (5), 474-480. doi:10.1016/j.clinbiomech.2005.12.014