Examination of a Measurement Method Using a Hand-Held Dynamometer of Hip Extensor Strength in the Sitting Position: Different Pelvic Positions and Fixation Affect Measurment

[Purpose] To examine the effects of hip position and the presence or absence of manual fixation on a measurement method using a hand-held dynamometer (HDD) to measure hip extensor strength in the sitting position. [Subjects] The subjects were 10 healthy males. [Methods] The subjects performed isometric hip extension in the prone position, and in the sitting position with the pelvis tilted anteriorly, neutrally, and posteriorly, and with and without pelvis fixation. Hip extensor strength was measured with a HDD, and the muscle activities of the trunk and hip extensors were measured by surface electromyography (sEMG). For each of the measurement conditions, the reproducibility and validity of the muscle strength value was investigated, as well as the differences in muscle strength and sEMG activity values among the conditions. [Results] Muscle strength reproducibility and validity was highest with the pelvis fixed in anterior tilt. In this position, muscle strength and gluteus maximus activity were significantly higher than their respective values in the other measurement positions. [Conclusion] With the pelvis fixed in anterior tilt, the measurement method has high reproducibility and validity.