Your ankles should remain flexible during the stride. The more rigid they are, the more force your body will experience as your foot contacts the ground. When your foot strikes the ground during forefoot running, your ankle should be plantar flexed (toes pointed down) at an angle greater than 90 degrees. When your heel strikes first, the ankle is dorsiflexed (toes point up) and the angle is less than 90 degrees. This makes it more likely your foot will slap down when heel striking.
During the support phase of the stride, the ankle should be dorsiflexed (figure 3.8a). This means the top of the foot is angled toward the body. From this position the ankle can release elasticity and power as the toes push against the ground to achieve plantar flexion in the push phase (figure 3.8b). If you are a heel striker, the angle at the ankle rarely is less than 90 degrees and therefore much of the elastic force is lost.
The ankle (a
) dorsiflexes during the support phase, then (b
) explosively shifts to plantar flexion during the push phase.
The knee should be slightly bent and relaxed when you land and just a little in front of your center of gravity. It remains slightly bent during the support phase (figure 3.9). As the body moves over the knee, it begins to straighten and is straight immediately before the big toe leaves the ground (figure 3.10). As the body goes through the drive phase, the other knee swings forward with the heel approaching the butt (figure 3.11). The heel reaches closer to the butt as speed increases. Allowing the knee to swing forward rather than forcing it forward allows the hip extensor muscles, especially the gluteal muscles, to complete their work of pulling the knee down and back without interference. The knee will swing high enough if it is relaxed and then the quadriceps can extend the lower leg and prepare for landing (figure 3.12). The relaxed, swinging action of the knee ensures the foot is high enough off the ground. If you sense your foot is too low, it may be because your knee is too low. Picturing yourself trying to spring over a small obstacle should help you swing your leg at the right height. As speed increases, the height of your swing should increase (figure 3.13).
Support phase: knee is slightly bent.
Straight knee immediately before big toe leaves the ground.
The knee swings forward as the heel approaches the butt.
Lower-leg extension in preparation for landing.
Higher knee swing associated with faster running.