Static and dynamic strength of the shoulder rotators in healthy, 45- to 75-year-old men and women.

Although clinicians routinely treat patients > 45 years of age and use ratio data in making treatment decisions, the reliability of performance of these individuals and the potential utility of ratio data are unclear. The purposes of the present study were to examine the reliability of peak torques and external/internal rotation (ER/IR) ratios for static, dynamic-concentric, and dynamic-eccentric tests and to determine the interrelationships between strength measurements in healthy 45- to 75-year-old subjects. Twenty men and 20 women (mean age = 59 +/- 9 years) were tested on two occasions, completed within 4-6 days. With subjects sitting and their dominant glenohumeral joint positioned in the scapular plane, two isolated contractions were completed at 0, 60, and 120 degrees/sec angular velocities. For peak torques (Nm), all 10 reliability coefficients > or = 0.83, whereas for external rotation/internal rotation (ER/IR) ratios (%), all five reliability coefficients < or = 0.67. Relative measurement error (standard error of measurement/ standard deviation) was much larger for ER/IR ratios (56-79%) than for peak torques (17-41%). Static and dynamic scores were highly related for peak torques (r = 0.72-0.89), but poorly related for ER/IR ratios (r = 0.23-0.36). The high variation associated with ratio data and its tendency not to follow the pattern of relationships which characterizes absolute data suggests that clinicians exercise caution when making treatment-related decisions using ratio data.

Shoulder rotator torques in female tennis and nontennis players.

The purposes of this study were to compare internal and external rotation torque measurements of the dominant arm during concentric and eccentric muscle actions, to determine the relationship between peak and average torques, and to compare shoulder rotator capabilities of tennis and nontennis playing women. Twenty healthy nontennis players and 20 healthy intercollegiate tennis players performed concentric-eccentric cycles at 60 degrees /sec angular velocity while seated with the glenohumeral joint at 45 degrees abduction and in the scapular plane (30 degrees horizontal flexion). No significant differences were observed between the two groups on peak or average torques within 115 degrees range of motion, on average torques within +/- 30 degrees of neutral, or on peak/average torque ratios (p > 0.05). Regardless of muscle action, the internal rotators produced significantly greater peak and average torques during eccentric actions than the external rotators (p < 0.01). Eccentric muscle actions produced significantly greater torques than concentric actions (p < 0.01). Peak torques were highly related to average torques within 115 degrees range of motion (r = 0.85-0.93) and less related within +/- 30 degrees of neutral (r = 0.76-0.91). This study provides comparative data for a test position and protocol that may be applicable early in rehabilitation. J Orthop Sports Phys Ther 1991;13(1):40-46.