Errors in Intra- and Inter-rater Measurements of Lower Limb Muscle Strength Using a Handheld Dynamometer

[Purpose] The purpose of this study was to verify the magnitude of errors in muscle strength measurement using a handheld dynamometer (HHD). [Participants and Methods] The study participants were 16 healthy adults (32 limbs). A HHD was used to measure lower limb muscle strength, including hip flexion, extension, abduction, adduction and knee extension. Each measurement was performed two times by two experienced raters to verify the magnitude of errors in intra- and inter-rater measurements. The errors for each measurement were estimated using the % minimum detectable change (%MDC). [Results] The error in intra-rater measurements of hip adduction was within “acceptable” limits. The errors in inter-rater measurements of hip abduction and adduction exceeded “acceptable” limits. The errors of the other items were “acceptable”. [Conclusion] When muscle strength is measured using an HHD, careful attention should be paid to the magnitude of errors found in this study.