Table 3 A regression slope of each kinematic variable at kilometers 8 and 40 and its slope difference between kilometers 8 and 40. Slope Slope difference Kinametic variables 8 km p value 40 km p value p value Stride length .013 .528 .020 .340 .521 Contact time -.005 .208 -.007 .113 .461 Peak knee flexion during support 2.299 < 0.001 * 4.085 < .001* < .002 †  Peak hip extension during swing .905 .480 1.024 .448 .887 Peak knee flexion during swing 2.853 .063 1.529 .341 .175 Peak hip flexion during swing 2.228 .072 .891 .449 .063 The fast runners had significantly more peak knee flexion at support than the slow runners. The fast runners decreased their peak knee flexion during support significantly less than the slow runners at 40 km when compared to 8 km.