Should you shorten your stride to run barefoot?
One of the suggestions often made to beginning barefoot runners is to shorten the stride in order to land on a foot directly under the body. While this seems to make sense at first glance, if you consider it more carefully it may be poor advice, at least for those who are willing to work on improving posture.Lets look at it more closely.
First, running speed is determined by the amplitude of leg extension. And, the more completely and quickly the leg extends, the further and faster that leg will recover. (See Running is jumping) We can see this in sprinters with fine form, notably, in videos of Carl Lewis. His legs straighten almost completely, both in extension, and in recovery. After a full extension, his recovering leg is released quickly forward, and his foot is already beginning to move backwards when it touches the ground. He is not landing on his foot, nor is he running into his leg. His foot takes the ground before his body descends from the arc of his stride. His body continues its forward movement and moves over the foot, which has simply been placed on the ground in front of the body. When you are out running, try reaching out to touch a fence or telephone pole, and pushing off from it as your body passes it. You can see that your arm can reach out, touch and follow an object that you are running past. So, too, your feet can reach for the ground and take the weight of your body in preparation for extension without creating a braking effect. This works best if the ball of your foot and toes touch the ground first, which they should do if you’ve extended the ankle at the end of the extension phase. (See: No Impact Running)
The actions of the legs and arms are linked and coordinated through the spinal musculature. The action of one leg is linked to that of the other through the spinal musculature such that the degree of extension of one leg determines the extent of recovery of the other. Further, as the foot of the recovering leg moves toward the ground, its synchronization with the extended leg allows it to link its return to the speed of the body over the surface on which the body moves. (See George Coghill, Serge Gracovetsky and the Spinal Engine)
So, why the advice to shorten running stride? First, runners who focus on leg recovery (leading with the knees, lifting the leg, drawing the foot up with the hamstrings) tend to truncate the extension phase and, thus, shorten their strides. Second, runners who try to run with the trunk vertical wind up similarly truncating the extension phase of the stride, as one cannot easily extend a leg from a vertical pelvis, and they wind up running into their legs, landing hard on a foot if it lands too far in front of the body. These runners have stabilized their hips such that the shock of landing is carried through their bones and to the joints, rather than allowing a fuller extension, which extends the arc of the stride permitting the recovering foot to arrive on the ground before the “fall” so that the co-ordinated musculature of the legs again takes the weight of the body. Runners with rigidly vertical trunks may try to get their feet down quickly underneath the body to reduce the force of landing, and wind up having to look for a faster turnover to compensate for shorter strides. I think there is a better way.
An evident physiognomic difference between terrestrial man and his arboreal ancestors is in limb length. Apes have longer arms – better for moving in the trees – man has longer legs – better for running. Man has evolved long legs in relation to the size and power of the gluteus muscles and their ability to fully extend those limbs in locomotion. If high-cadence, short-stride running were really more efficient, the evolutionary process would not have resulted in lean, long-limbed runners, and dachshunds would be better runners than are greyhounds.
The reason that some studies show increased efficiency in some runners through shortening of stride is because the runners studied have postural faults that make full extension effortful. The general postural condition of modern man is one of global retraction. We hunch over our desks, we slouch in our chairs, we slump while standing. We run with our heads retracted, with our shoulders lifted, with our hands balled into fists, and, yes, with short strides. To attempt to correct this retraction with increased effort takes more energy. To force oneself to stand and sit “straight” doesn’t work. We need to learn to take the effort out of posture, to undo the retraction. Then a longer running stride will be able to do itself.
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