Because your stride length is so short, you don’t hit the ground very hard, and ground contact is typically made with the outside of the heel, with your foot only a few inches in front of you. To run fast while hybrid running, gradually increase your stride length and try to spend as little time on the ground as possible (you hit the ground like a

possible and focus on rapidly pushing off with your calf muscles to initiate a brief airborne phase. Almost all force associated with slow hybrid running comes from your calves and Achilles tendons.

Think of slow hybrid running as a shuffle run in which you generate force by moving your hips in a scissors-like action while moving your knees through a small range of motion. Spend as little time on the ground as

fast hybrid running how the ranges of hip flexion and extension increase (Fig. 2.5), which allows for the longer stride lengths necessary to run fast. To keep the center of mass relatively flat, the knee has to be flexed 40° during midstance while fast hybrid running.

In slow hybrid running, the initial point of contact is almost always the outer heel, which makes initial contact only 2½ inches (6.35 cm) in front of the center of mass.

maintain economy, the best hybrid runners must “fine-tune” the positions of their limbs prior to contact in order to provide just enough stiffness to absorb and return energy at each successive running speed: Too much stiffness, and the center of mass moves up and down excessively and impact forces increase; too little stiffness, and the pathway of

that people would choose an intermediate gait referred to as “pendular running.” In this gait pattern, which I like to call “hybrid running,” the stride length is shortened, the airborne phase is reduced, and the lower limbs are stiff for brief periods during stance phase

all in-between speeds, the computer model suggested

walking and sprint running were only used at the extremes of speed: