STATIC AND DYNAMIC STRENGTH OF THE SHOULDER ROTATORS IN HEALTHY, 45-YEAR-OLD 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 performan ce of these individuals and the potential utility oi ratio data are un clear, The purposes oi the present study were to examine the reliabili ty of peak torques and external/internal rotation (ER/IR) ratios for s tatic, dynamic-concentric, and dynamic-eccentric tests and to determin e 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 s ubjects sitting and their dominant glenohumeral joint positioned in th e scapular plane, two isolated contractions were completed at 0, 60, a nd 120 degrees/sec angular velocities. For peak torques (Nm), all 10 r eliability coefficients greater than or equal to 0.83, whereas for ext ernal rotation/internal rotation (ER/IR) ratios (%) all live reliabili ty coefficients less than or equal to 0.67. Relative measurement error (standard error of measurement/standard deviation) was much larger fo r ER/IR ratios (56-79%) than for peak torques (17-41%). Static and dyn amic 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 as sociated with ratio data and its tendency not to follow the pattern oi relationships which characterizes absolute data suggests that clinici ans exercise caution when making treatment-related decisions using rat io data.