Fig. 4. Orientation and body angles used in the present study. The heading angle () was defined as the angle between the projection of the longitudinal axis of the body on the horizontal plane (X_g–Y_g) and the X_g axis; the elevation angle () was defined as the angle between the longitudinal axis of the body and the horizontal plane (X_g–Y_g); and the bank angle () was defined as the angle between the line connecting both chest markers and the horizontal plane (X_g–Y_g) (see inset). Body angles were defined as the deviation around the body-fixed axes in a body coordinate system. Arrows define the positive rotation direction of the body angles. Rotations about the body-centered X_bY_bZ_b axes were designated roll, pitch and yaw, respectively. X_bY_bZ_b, dynamic, body-based coordinate system, centered on the hip.