Comparison of the test-retest reliability of hip strength measurements using dynamometer fixed by hand versus fixed to a stable frame in female athletes

Assessment of hip strength needs a reliable method. Hand-held dynamometers are appropriate alternatives for manual muscle testing and isokinetics. Stabilizing the dynamometer with hand will increase error in measurements. The purpose of this study was to compare the test-retest reliability of hand-held dynamometer fixed by hand and fixed to a new stable frame for measuring hip extension, abduction and external rotation strength in healthy female athletes.

Normalized average and peak values of torque of three successive trials for each muscle group were calculated in two sessions one week apart in ten healthy female athletes. Strength was measured with hand-held dynamometer fixed by hand and fixed to the stable frame in each session. Intra-class correlation coefficients (ICC), coefficients of variation (CV) and standard error of measurement (SEM) were calculated to determine the reliability.

For hip extension, abduction, and external rotation strength measured by hand fixation. The ICC ranged from -1.22 to 0.6, the CV ranged from 8% to 33% and the SEM ranged from 0.007 to 0.04. For strength measurements with stable frame, the ICC ranged from. 93 to. 96, and CV ranged from 5.26% to 7.94%. The range of the SEM was from. 004 to. 08.

Measurements of hip muscles strength with a dynamometer fixed to a stable frame showed higher reliability than fixation by hand in young female athletes. These findings support the error within hand fixation of dynamometers and the necessity for providing better fixation.