Measurement properties of hip strength measured by handheld dynamometry: Reliability and validity across the range of motion.

OBJECTIVES

Different angles and positions may influence the reliability and validity of hip strength dynamometry. This study examined the reliability and validity of hip strength measured with belt-stabilized handheld dynamometry (HHD) compared to isokinetic dynamometry (IKD) across multiple angles.

DESIGN

Repeated measures.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Thirty healthy participants completed 3 sessions.

MAIN OUTCOME MEASURES

Hip torque was measured for hip abduction (ABD; -10°, 0°, 20°, and 40°), internal rotation (IR; -30°, -15°, 0°, 15°, and 30°), external rotation (ER; -30°, -15°, 0°, 15°, and 30°), and extension (EXT; -10°, 0°, 30°, 60°, 90°, and 120°).

RESULTS

ABD was reliable (no intratester reliability differences p = 0.409-0.997; ICC = 0.624-0.900) and valid (no HHD-IKD difference p = 0.270-0.946; r = 0.556-0.624) measure. IR had questionable reliability (intratester reliability differences p = 0.001-0.043; ICC = 0.682-0.879) and validity (HHD-IKD differences p < 0.001; r = 0.393-0.771). ER was reliable (no intratester reliability differences p = 0.226-0.937; ICC = 0.731-0.876) but not valid (HHD-IKD differences p < 0.001-0.003; r = 0.194-0.651). EXT showed varying levels of reliability and validity; 30° was both reliable and valid. Peak torque occurred in a lengthened position for ABD, ER, and IR, and at 90° of hip flexion for EXT.

CONCLUSIONS

HHD can be an effective tool for measuring strength under certain circumstances; however, IR/ER testing should be used with caution.