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Background and aim: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.

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Background and Aim: Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition. Women with patellofemoral pain syndrome would present significant weakness in many of hip muscle groups when compared with the healthy group. The objective of the present study was to compare the strength of hip abductor, extensor and external rotator muscle groups in sedentary women with bilateral patellofemoral pain syndrome to a matched control group of sedentary women without patellofemoral pain syndrome. 

Materials and Methods: Twelve women with bilateral patellofemoral pain syndrome as experimental group and other twelve matched women as control group participated in this study. Maximum isometric strength for three hip muscles including abductor, extensor and external rotator muscle groups was measured bilaterally in all subjects using a dynamometer fixed on a platform and finally averaged between two limbs and compared with the control group.

Results: The hip abductor, extensor and external rotator muscle groups of experimental group were statistically weaker than that of the control group (p< 0.001).

Conclusion:  It seems that lower limb muscles including hip muscles of women with patellofemoral pain syndrome become weaker due to disuse conditions.