Age-related changes in normal isometric shoulder strength

Normative data are useful for assessing isometric shoulder strength in pati ents with bilateral shoulder abnormalities. The purpose of this study was t o develop a normative database for shoulder strength in the clinically rele vant positions and movements. Twenty combinations of exertions and postures -including flexion, extension, abduction, adduction, internal rotation, and external rotation-were tested for both the dominant and nondominant sides. Strength was measured isometrically using a modified Cybex II dynamometer. The cross-sectional study design included 120 subjects (60 women and 60 me n) ranging in age from 20 to 78 years from southern Minnesota. Tables of no rmative strength data were constructed. Multivariate analyses were performe d to assess the effect of age, sex, and weight on strength. Age was negativ ely associated with all strength measures, and weight was positively associ ated with them. Men were stronger than women when controlling for age and w eight. Statistically significant differences between dominant and nondomina nt shoulders were found for only some of the strength measures taken. These normal data will be useful to the clinician, as they permit a standard aga inst which to compare shoulder strength.