Well?
Well?
You don't. People just like to make stuff up to support their argument. You can argue that they're "braking" when they land on their forefoot.
Running is a propulsionary action which means you exert force into the ground, pushing you forward.
You can not push into the ground until your Center of Gravity is in front of your point of impact/your heelstrike, until so, you are pulling your center of gravity towards the point of impact.
Elite runners land with the COG above or in front of their point of contact so that as soon as they land, they can begin pushing into the ground to propel themselves forward. By doing the opposite, landing with the point of impact in front of the COG, your lead leg must act as a coilspring, dissapating the shock, until you can pull your COG above the point of impact and begin pushing into the ground.
A sprinter's foot strike, is similar well infront of the center of gravity, but a good sprinter will not slow their momenum from having a foot strike infront of their COG, instead they begin pulling from that point, until the foot passes under the COG, then they push. The entire leg, including the foot acts as a spring in this case. The associated loss in momentum is the cost of the added propulsion from pulling and compressing the leg-foot spring action. This sort of movement is necessary for moving fast.
As a distance runner you can (and will) do the same thing throughout a race, but it is less efficient to pull than to push, and often this difference can vary greatly from runner to runner.
biomechanist wrote:
Running is a propulsionary action which means you exert force into the ground, pushing you forward.
You can not push into the ground until your Center of Gravity is in front of your point of impact/your heelstrike, until so, you are pulling your center of gravity towards the point of impact.
Elite runners land with the COG above or in front of their point of contact so that as soon as they land, they can begin pushing into the ground to propel themselves forward. By doing the opposite, landing with the point of impact in front of the COG, your lead leg must act as a coilspring, dissapating the shock, until you can pull your COG above the point of impact and begin pushing into the ground.
Does that come with soup or salad?
i don't get it
Whe I became a forefoot striker I became alot faster.
Sprinter Guy dude Sir: "A sprinter's foot strike, is similar well infront of the center of gravity..."
Reference?
Please provide video of your form before and after you became a forefoot striker along with your various pr's both before and after. Thanks.
noodler wrote:
Whe I became a forefoot striker I became alot faster.
Thanks for your n=1 study. Now, care to offer some explanation of how forefoot striking is so much better, or (gasp!) evidence for your theory?
Here's how I explain it to the kids, and they generally get the idea. It's the difference between a square wheel and a round wheel in the caveman era. The square wheel works, but it is a clunker. It appears to stop momentarily every time it contacts the ground, then catches up and rotates over the point of contact, and wastes energy as it clunks along. The round wheel just rolls, baby. Heel vs. mid- or fore-foot stiking is not much different.
biomechanist wrote:
Running is a propulsionary action which means you exert force into the ground, pushing you forward.
No, for some champion-level runners, it is not an exclusionary 'push' force, but instead, groundstrike is a 'pull then push', as the center of mass shifts forward over the foot. In such cases, the reactionary ground force from the 'pull' is less than the ensuing 'push' force.
Sprinter Guy dude Sir wrote:
A sprinter's foot strike, is similar well infront of the center of gravity, but a good sprinter will not slow their momenum from having a foot strike infront of their COG, instead they begin pulling from that point, until the foot passes under the COG, then they push. The entire leg, including the foot acts as a spring in this case. The associated loss in momentum is the cost of the added propulsion from pulling and compressing the leg-foot spring action. This sort of movement is necessary for moving fast.
As a distance runner you can (and will) do the same thing throughout a race, but it is less efficient to pull than to push, and often this difference can vary greatly from runner to runner.
Sprinters do NOT strike in front of the center of gravity. My sprint coach (400 coach) told me to strike below or just behind where your center of mass is. Think of it in terms of force vectors. If you plant in front of your center of gravity the force vector is going basically up your leg, this means there is a portion of the vector pushing back (against your motion) and up. If you plant below or behind this braking force (force opposing your motion) is not there.
All distance runners have a footstrike in front of their center of gravity (COG).
Every distance runner also has a toeoff behind their COG.
The thing to notice here is that the toeoff is more behind their COG than their footstrike is in front of their COG. This in part accounts for the more forward push with every stride to overcome wind resistance.
Sprinters only seem to have their footstrike under or behind the COG during rapid acceleration. Once constant speed is reached, footstrike is in front of the COG.
http://www.youtube.com/watch?v=Bxv5IUb_JNs
In the video, Moses Kipkosgei's footstrike is well in front of his COG. But his impact is quite soft, with vertical forces absorbed slowly. The overall braking effect is quite minimal.
Peter Kamais has a footstrike less in front of his COG. However, his impact is much more rigid, with vertical forces absorbed very quickly. Just a subjective observation here, but his overall braking effect is virtually the same as Kipkosgei's.
The idea that the point of impact needs to be behind the center of gravity, while often perpetuated, is never accompanied by any actual proof.While not a direct analogy, a front wheel drive car seems to work just fine while exerting force in front of its center of mass.Also, when walking all human beings land on their heels and then roll forward. I suspect that walking has evolved to be fairly efficient (probably more so than running), why do we heel strike then?
biomechanist wrote:
Running is a propulsionary action which means you exert force into the ground, pushing you forward.
You can not push into the ground until your Center of Gravity is in front of your point of impact/your heelstrike, until so, you are pulling your center of gravity towards the point of impact.
Elite runners land with the COG above or in front of their point of contact so that as soon as they land, they can begin pushing into the ground to propel themselves forward. By doing the opposite, landing with the point of impact in front of the COG, your lead leg must act as a coilspring, dissapating the shock, until you can pull your COG above the point of impact and begin pushing into the ground.
However you naturally hit the ground, it is important to be as efficient as possible. This means making ground contact directly underneath your center of gravity and using a light strike; don't stomp. When running, you should try to run like you would run for the bus as this often is one of the most effecient ways to run. You should make tweaks from there, but overall when running you should try this. If you are a heel striker who makes ground contact way out in front of your body (overstriding), you will get more benefit from just bringing this under control than you would from changing to a forefoot strike.
Forefoot strike refers to making initial contact on the balls of your feet rather than on the heel. There are a small percentage of people who are natural forefoot strikers. Sometimes they are runners who ran track in high school or played sports that involved cleats (try heel striking in a cleat once and you will not do it again). Other times one cannot really point to the genesis of their strike; that is just how they run. Either way, they tend to make ground contact more softly than heel strikers and have a slightly more efficient natural gait. In some cases, this results in fewer injuries to the knees and hips.
bump
Everyone lands a little in front of their center of gravity. It's impossible to land directly under it. That is an old wive's tale.
http://www.runblogger.com/2010/08/on-running-form-ii-where-should.html
http://www.scienceofrunning.com/2010/08/why-we-land-in-front-of-our-center-of.html
The facts wrote:
Either way, they tend to make ground contact more softly than heel strikers and have a slightly more efficient natural gait. In some cases, this results in fewer injuries to the knees and hips.
I disagree with the statement that forefoot runners make ground contact more softly than heel strikers.
I hit with my heel first. However, the impact force is minimal as I quickly roll along the side of my foot and pronate to push off with the big toe. In fact, my foot falls are so quiet, I can usually sneak up on slower runners such that they are startled when I pass. My friends who are forefoot strikers have a much heavier foot fall. They also have all kinds of achilles/calf injuries that I have generally avoided.
I think what is called "heel striking" is not so inefficient. When you wear a running shoe with a two inch heel, you are going to strike with your heel just because there is too much heel on the shoe.
Would all you engineers agree the the less time/friction with the foot in front of your CG the better?
P.S. I'm an engineer too.