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Background and aim: The ability to maintain upright stance is essential in gait and initiation of voluntary movements that are vital not only for sport but also for activity of daily living .Lateral ankle sprains are common in athletes and are most prevalent in jumping sports such as volleyball , football and basketball .Although these injuries are common after direct contact. It may occur in non contact mechanism such as landing from a jump. Neuromuscular control plays a major role in dynamic joint stability. Most of ankle joint injuries occur in jump-landing task and at the end of sport activitiesparticularly when the athlete is fatigued. Our purpose was to evaluate the effects of ankle muscle fatigue on dynamic postural stability in jump landing task. 

Material and methods: Twenty two healthy women athletes (age:22.8±1.7 years, height:160.3±4.9 cm and weight:56.2±5.8  kg) volunteered to participate in this study .Two test sessions were done with a rest period of one week between them . During each session, effect of one group of ankle muscles (sagital or frontal movers) on dynamic postural stability was assessed. Postural stability was evaluated for 5 seconds after landing on force plate by postural stability indices ( Medial/Lateral, Anterior/Posterior, Vertical and Dynamic Postural Stability Indices) before and after isokinetic fatigue of ankle muscles.

Results: The finding indicate significant increase in all stability indices after isokinetic fatigue of ankle muscles (p<0.05).

Conclusion:These results indicate that isokinetic fatigue of ankle muscles significantly decrease postural control ability in healthy women athlete. 

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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.