Fig. 1. Differences in knee flexion between conditions. (A) Level condition subjects were exercised at 0° pitch, whereas Incline subjects were exercised at 20°, resulting in a more acute angle of knee flexion () at peak normal ground reaction force (nGRF) oriented perpendicularly to the track surface. (B) Differences in knee flexion () are expected to result in differences in the orientation of compressive loads (dotted lines) relative to the distal femur in the parasagittal plane, because the joint reaction force (JRF; gray arrow) is transmitted more posteriorly on the femoral condyles. Mean knee flexion at peak GRF: Level, 76.3±1.33°, mean ± s.e.m., N=16 strides; Incline, 62.6±3.52°, N=10 strides; P<0.01, Student's t-test.