Falling Toward the Finish talked about using gravity to help pull a runner forward. A similar visualization helps to clarify why landing feet way out in front of you makes for inefficient running.
First off, imagine running down a steep hill, gravity pulling you forward so much you’re in danger of losing control; a natural response – aside from just stopping (or in fact especially if you decide to stop) – is to stretch your strides so the foot hits well in front of your center of gravity. A portion of your body’s forward momentum is then transmitted right down through that outstretched leg, pressing the foot harder against the surface (one reason your foot is more likely to skid along the ground running downhill than on level ground). To the extent you don’t skid, it means friction between sole and earth is eating up momentum, transferring forward motion into grinding and heat. By landing the foot out front, you’re ‘hitting the brakes’ a little bit with every stride.
Second, even on level ground, since the length of your extended leg is fixed, the farther in front your foot hits, the lower your body is to the ground. (Not so obvious? You can prove it with trigonometry if you’re into that, but for the rest of us, stand with feet together, then lift one foot and place it out in front of you – feel your entire torso dropping toward the floor?). In order for your body to move forward over that planted foot, it needs to move upward, like an upside down pendulum. You see this in runners whose feet strike well-ahead of them, a bobbing motion as their bodies rise up and drop down, up and down. (When I first started running, my kids called me ‘the Energizer Bunny’ because of that bobbing, almost hopping, motion; kids can be pretty astute sometimes…) At a cadence of 180 steps per minute, that means lifting your torso, arms and head – the majority of your body weight – some distance, 180 times per minute; a considerable expenditure of energy on something that is not direct forward motion.
And third, the farther you swing your leg out forward, the longer it takes for your body to move past it, which means you can take fewer strides per minute. That might be OK – theoretically, a smaller number of longer strides could gain more distance than a greater number of shorter strides – but since those long strides require extra energy to lift the body and to overcome braking, that leaves less energy to accomplish forward motion – it’s just plain less efficient. Studies of elite runners prove this out, showing a near-universal correlation between high cadence and speed. Long bounding strides are relaxing and can be useful to ‘mix it up,’ relieving strains while covering long distance, but they are not as efficient as quick turnunder (that’s like turnover, only since the feet are under us… OK, so, like, forget I said that…).
Avoid the braking effect, reduce energy-wasting up-and-down motion, and allow more strides per minute – multiple reasons why landing the feet beneath the body can help MPRs achieve their full potential.