Efficient runners time their movements such that the heel and lower leg swing up using momentum instead of expending energy.
When the foot leaves the ground and begins the follow-through phase, the foot, shoe and lower leg carry significant angular momentum. Most runners pause in this position, gliding through the air and waiting for gravity to pull them down into the ground.
During this time, angular momentum dissipates. When they hit the ground with one leg, they must contract the hamstring muscles of the opposite leg to lift the heel and initiate leg recovery.
Efficient runners don't pause in their stride cycle, but actually initiate leg recovery before completion of follow-through. Instead of contracting the hamstring muscles to lift the heel, they drive the knee forward using the hip flexor muscle. The upper leg driving forward while the lower leg and foot are still moving backward causes the lower leg and foot to swing up, without hamstring contractions.
Overlapping follow-through and leg recovery phases this way reduces the energy cost of leg recovery and associated hamstring fatigue. Learn to recover your leg this way and you will run faster, farther and with fewer injuries.
Ken Mierke is head coach of Fitness Concepts (www.Fitness-Concepts.com), developer of Evolution Running (www.EvolutionRunning.com) and author of The Triathlete's Guide to Run Training. Ken's book and video, Evolution Running: Run Faster with Fewer Injuries, are both available on his Web sites.