Inclusion Criteria:  Navicular drop tests (NDT) 10 mm or larger difference in the navicular tuberosity heights. Age range from 18-30 years from both sexes to limit the effects of arthritic changes that would be caused by bilateral FFF over the age 30. BMI 18-30 as the prevalence of flexible flatfoot appears to be higher in individuals with a higher body mass index (BMI).  Exclusion Criteria:  history of lower extremity injuries as fractures, congenital deformities or surgery affecting balance. history of cerebral concussions affecting balance. visual or vestibular disorders, and/or any neurological deficit affecting balance. any sign of foot pain, history of patellofemoral pain syndrome, plantar fasciitis, TA or TP dysfunction affecting foot function and balance.