Relationship between Grade 3 Muscle Strength and the Maximum Muscle Strength in Manual Muscle Testing of Legs: Assessment of Flexion and Extension of the Hip and Knee Joints

Abstract

[Purpose] The purpose of this study was to clarify the relationship between grade 3 muscle strength and the maximum muscle strength of manual muscle testing established by Daniels et al. [Subjects] The subjects were the dominant legs of 21 healthy persons (mean age: 23.3 years). [Methods] Experimental tasks included maximum force static muscle contraction in flexion and extension of the hip and knee joints. The maximum resistance in each task was determined with a hand-held dynamometer. The relationships between grade 3 muscle strength and the maximum muscle strength were tested using regression analysis and analysis of covariance. [Results] We confirmed that all of the 4 regression equations could be used to predict the maximum muscle strength. The regression equation for flexion of the hip joint was the same as that for extension of the joint, while the regression equation for flexion of the knee joint differed from that of extension of the joint. [Conclusion] This study found there is a linear correlation between grade 3 muscle strength and the maximum muscle strength, and that the correlation was different for each motion.