The goal of this study is to see the effect of the combination of biodex balance system and short foot exercise in the treatment of subjects with flexible flat foot. The main question is the effect of biodex balance training and short foot exercise on myoelectric activity of subjects with flexible flat foot experimental participant will receive biodex balance system exercise and short foot exercise for 4 weeks controlled participant will receive short foot exercise and stretching exercise for 4 weeks Assessment will be done pre and post treatment by using Navicular drop test Myoelectric activity of paraspinal muscle Dynamic balance Pain severity Functional ankle instability inder

Inclusion Criteria:

• 1) Sixty subjects from both gender with bilateral flexible flat foot will be selected with their age between 18 to 30Years old 2) Body Mass Index (BMI) was ranging from 18 to 25 kg/m2 3) The participants were eligible to be included if had bilaterally FFF according to the navicular drop test 4) Required participant to have been diagnosed (by an orthopedist) with flexible flat foot

Exclusion Criteria:

• Repeated lower extremity injuries as fractures or deformities. 2) History of surgery to the lower extremity. 3) History of cerebral concussions, and visual or vestibular disorders. 4) Any neurological deficit affecting balance. 5) Any medication can affect the balance 6) Any problem of lumbar spine( disc,spondylolisthrsis)