RELATIONSHIP BETWEEN REARFOOT AND FOREFOOT ORIENTATION AND GROUND REACTION FORCES DURING RUNNING

In this study, footprint and ground reaction forces (GRF) were simulta neously recorded from 32 male subjects running barefoot. Angle between the rearfoot and the forefoot in static (alpha S) and in running (alp ha R) conditions, and orientation of both, rearfoot (alpha rf) and for efoot (alpha ff) with the direction of running (DOR), were measured an d correlated to selected GRF parameters. The dynamic rearfoot/forefoot angle (alpha R) was correlated, positively with arch deformation (r = 0.58, P < 0.001), vertical Fz loading peak (r = 0.60, P < 0.001), med iolateral, and anteroposterior force rates (r = 0.47 and 0.48, P < 0.0 1), and negatively with stance time (r = -0.41, P < 0.05) and total co urse of the force application point path (r = -0.71, P < 0.001). Both a medial and a lateral rotation were observed on footprint between the rearfoot and the forefoot in the horizontal plane. A medially rotated forefoot (''closed foot'') was associated to a rigid and inverted foo t, whereas a laterally rotated forefoot (''open foot'') was associated to a flexible and everted foot.