Reliability of measurements of knee extensor muscle strength using a pull-type hand-held dynamometer

[Purpose] The purpose of this study was to examine the intra-examiner and inter-examiner reliabilities of measurements of knee extensor muscle strength using a pull-type hand-held dynamometer (HHD). [Subjects] Fifty-four healthy adults (35 males; average age, 23 years) participated in this study. [Methods] Knee extensor muscle strength of each leg was measured three times using the HHD. To examine the intra- and inter-examiner reliabilities, measurements were performed by two examiners, a physical therapist and a physical therapy student. [Results] The intra-examiner reliabilities, ICC (1, 1) and ICC (1, 3) ranged from 0.94–0.99. The inter-examiner reliabilities, ICC (2, 1) and ICC (3, 1) ranged from 0.90–0.92 for the right leg, and 0.88−0.90 for the left leg. Neither constant nor proportional errors were found by Bland-Altman analysis. [Conclusion] Intra-examiner and inter-examiner reliabilities were acceptable, indicating that muscle strength can be measured with the pull-type HHD without dependence on skill of measurement. Pain was not caused by measurements with the pull-type HHD.