The effect of insole on ground reaction forces of two-legged vertical jumping for heading ball in flexible flat foot male subjects

To determine the effectiveness of insole for flexible flat foot subjects with and without insole during stance phase of two-legged vertical jumping on a force plate for heading a ball.

Randomized assignment of participants for this prospective study.

To measure salient points of three dimensional ground reaction forces and some temporal events of these points. A force plate flush mounted in the floor was used.

Fifteen FF foot subjects and fifteen normal foot subjects of male sex voluntarily participated in this study. The mean, ±SD of age, height, and weight of the normal foot subjects were 23.13, ±2.72 years, 176.40, ±5.03cm, and 69.55, ±8.31 kg; and those of the FF foot subjects were 22.73, ±2.31years, 174.60, ±4.13 cm, and 69.87, ±9.2 kg, respectively.

The use of insole could not have significant effect on parameters regarding saggital and mediolateral directions in the normal and FF foot subjects. Moreover, findings of GRF related to vertical direction for maximum force due to take off and stance duration revealed significant differences between the normal foot and FF foot subjects without insole (p< 0.05 respectively) and insignificant differences between the normal foot and FF foot subjects with insole adoption (p> 0.05 respectively).

The results of this study revealed that the use of insole in the FF foot subjects can be significantly effective in increase of stance time duration and decrease of magnitude of GRF of take off as the main constitution of vertical jumping.