Comparison of Reliability of Isometric Leg Muscle Strength Measurements Made Using a Hand-Held Dynamometer with and without a Restraining Belt

[Purpose] The aim of this study was to evaluate whether using a belt to restrain a hand-held dynamometer improves reliability of isometric leg muscle strength measurements in healthy subjects. [Subjects] Twenty to 44 healthy subjects participated in the test. [Methods] Two raters, one man and one woman, used a hand-held dynamometer with or without a restraining belt to measure the isometric strengths of the following muscle groups: flexors, extensors, abductors, adductors, internal rotators and external rotators of the hip; flexors and extensors of the knee; and dorsiflexors and plantar flexors of the ankle. [Results] The intraclass correlation coefficient, used to describe interrater agreement, ranged from 0.97 to 0.99 with the belt and from 0.21 to 0.88 without the belt. Pearson's correlation coefficient for measurements with versus without the belt ranged from 0.61 to 0.95 for the man and from 0.31 to 0.87 for the woman. [Conclusion] The interrater reliability of isometric leg muscle strength measurements was improved by use of a belt to restrain the hand-held dynamometer.