Standards for Judgments of Unilateral Impairments in Muscle Strength

Abstract

A secondary analysis of a data base of isometric strength measures from 136 asymptomatic adults (50–79 years) was conducted to estimate the normal difference between dominant and nondominant side strengths. Measures of strength obtained by hand-held dynamometry from 13 muscle actions were expressed as a ratio, dominant side strength:nondominant side strength. The ratios indicated that the dominant side was stronger on average but that the normal range of differences between sides could reach 23.2 to 40.2%, depending on the action. The findings do not provide much support for the convention of using a 10% difference in strength between sides to designate impairment.