Shoulder muscle strengh in asyntomatic patients, according to age, sex and method of determination

OBJECTIVE: Determine the normal value of shoulder muscle strengh, in an adult population divided in six groups between 20 to 86 years, without known shoulder pathology. MATERIALS AND METHODS: 523 individuals, 1046 shoulders, had their muscle strengh evaluated in two different positions, in 90 abduction and 90º fowarf flexion in the scapular plane. Three measurements were performed and the aveage one was recorded. Patiens with known shoulder pathology, reumathoid diseases, cancer were excluded. The patients were divided in six groups according to age, from 20 to 29 (68 patients), 30 to 39 (92 patients), 40 to 49 (109 patients), 50 to 59 (103 patients), 60 to 69 (91 patients) and 70 to 90 (60 patients). The strengh eas measured in pounds. RESULTS: Average mucle strengh was 17,64 at the scapular plane and 16,82 lb at 90ª (p<0,0001)For the right shoulder, the average muscle strengh of the second decade group was 22 lb at scapular plane and 20,73 at 90º. The third decade was 19,93 and 18,50 respectively. The fouth decade values were 20,45 and 19,58, on the fifth decade 17,83 and 17,07. On the sixth decade was 15,57 and 15,23 and for the seventh decade was 11,40 and 11 lb respectively. The values for the left shoulder were for the second decade 21,53 om the scapular plane and 20,53 at 90º. On the third decade were 19,33 and 18,17, on the fourth decade 19,62 and 18,95, on the fifth decade were 16,8 and 16,2 , on the sixth decade 15,57 and 15,23. And for the final group 11,4 and 11 lb. Significant differences were seen between both shoulders ,sex (p<0,0001), position of the arm at time of measure (p0,0001), dominace (p0,001) CONCLUSION: The objective measurement of the muscle strengh of the shoulder varies significantly with age, sex and position of the arm at time of measure, putting in dout the validity of the contralateral shoulder as a value to compare against.