The purpose of this study was to investigate kinetic characteristics of distance running on the uphill. Six varsity distance runners were asked to run on the slopes of different inclinations (0, 3.2, 6.4, and 9.1 %) at three running speeds (5.0, 4.2, and 3.3 m/s) on the overground. Subjects were videotaped with a high speed video camera. Ground reaction forces (GRF) were measured with two force platforms mounted in a specially-made runway, 12 m in length, on the slope. Two dimensional coordinates of body segment endpoints were obtained by a panning DLT method. Joint torques and joint torque powers of the lower limb joints were calculated on a planar link model. GRF data normalized by the support time and the joint torque and joint torque power normalized by the time of one running cycle were averaged.
In the steep slopes (6.4% and 9.1%), the vertical impact force just after the foot contact was small and the maximum loading rate was significantly smaller than the level condition. There was no significant difference in the impulse and the peak value of the vertical and horizontal GRF among four inclinations. The hip extensors' torque just before the foot contact and the hip positive power before and after the foot contact significantly increased as the inclination increased. The hip flexors' torque and the positive power just after toe-off significantly increased as the inclination increased. These results reveal that, the impact shock just after the foot contact was smaller and hip torque power during the swing phase was enhanced in the uphill running. In the support phase, there was little difference in the peak value and the pattern of the joint torques among the inclinations. However, the positive powers of the lower limb joints during the second half of the support phase increased in the uphill running due to larger extension velocities of the lower limb joints.
