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

Abstract

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.

Keywords: Curves; Error; Intratester reliability; Torque.