Introduction: Flatfoot is one of the most common foot deformities that have a high impact not only on the lower limb but also on the pelvis and the spine.
Purpose: The purpose of this study was to compare hip performance (hip muscle fatigue time, proprioception, dynamic balance, and muscle strength) and the effect of hip muscle fatigue on hip extensors and abductors strength between adults with flexible flatfoot and matched healthy volunteers.
Methods: twenty four healthy and twenty tow adults with bilateral flexible flatfoot volunteers from both genders were recruited. Hip joint position sense was evaluated by digital inclinometer, hip extensors and abductors strength were assessed before and after fatigue protocol by the handheld dynamometer, and dynamic balance was assessed using the Y balance test. All tests were carried out for the dominant leg in both groups for comparison.
Results: The fatigue time and strength of hip extensors and abductors were significantly lower in the flatfoot group compared to healthy individuals (p < 0.05). Furthermore, a significant difference was observed in hip joint position sense (JPS) and dynamic balance. (p < 0.05).
Conclusion: The current study suggested that the fatigability of the hip extensor and abductor was higher and negatively affected the strength more in flatfoot subjects. The accuracy of hip joint position and dynamic balance appears to be lower among those populations. which must be considered in clinical evaluation and treatment.