Is a long femur or tibia better for running

BoneStructure wrote:

Is a long femur more beneficial as opposed to a long tibia, or is it the other way around?

Tibia is more important. I think there are mechanical reasons, but also it's lighter.

Tibia for sure. You can extend the tib/fib segment at a much more acute angle relative to the ground (more parallel to the ground)during propulsion (when the leg is behind you), than the femur is capable (can only extend about 10-15 degrees from vertical) when the torso is vertical. This gives advantage if the tibial segment is longer, allowing one to cover more ground per stride than a limb with a short tibia/long femur ratio.

It also follows that good ankle extension at end stage propulsion further enhances the stride length.

Femur, easily.

Just wow... wrote:

Tibia for sure. You can extend the tib/fib segment at a much more acute angle relative to the ground (more parallel to the ground)during propulsion (when the leg is behind you), than the femur is capable (can only extend about 10-15 degrees from vertical) when the torso is vertical. This gives advantage if the tibial segment is longer, allowing one to cover more ground per stride than a limb with a short tibia/long femur ratio.

Reductive argument. Everyone has different biomechanics.

MENTALITY > physicality

http://www1.pictures.zimbio.com/gi/Tsegaye+Kebede+Virgin+London+Marathon+2010+0a-zSMJD46ol.jpg

wow at you wrote:

Just wow... wrote:

Tibia for sure. You can extend the tib/fib segment at a much more acute angle relative to the ground (more parallel to the ground)during propulsion (when the leg is behind you), than the femur is capable (can only extend about 10-15 degrees from vertical) when the torso is vertical. This gives advantage if the tibial segment is longer, allowing one to cover more ground per stride than a limb with a short tibia/long femur ratio.

Reductive argument. Everyone has different biomechanics.

Agreed, but if you remove all other variables, there is a mechanical advantage to the long tibia.

Just wow... wrote:

wow at you wrote:

Reductive argument. Everyone has different biomechanics.

Agreed, but if you remove all other variables, there is a mechanical advantage to the long tibia.

Only in your imagination.

its not length but proportional length

but having a greater percentage of tibia length to the leg/persons height is more beneficial (there will be a point where you see diminishing returns if it is too long but it would be so extreme it isnt something you actually see)

for cycling the femur becomes more important

leg biomechanics wrote:

its not length but proportional length

but having a greater percentage of tibia length to the leg/persons height is more beneficial (there will be a point where you see diminishing returns if it is too long but it would be so extreme it isnt something you actually see)

for cycling the femur becomes more important

Yes.

just look at how the Kenyans are built. long tibia with little calf muscle mass.

You're implying that a longer stride is better. But stride length x stride rate = running pace.

Your argument is reductive nonsense.

wow at you wrote:

You're implying that a longer stride is better. But stride length x stride rate = running pace.

Your argument is reductive nonsense.

I'm asserting that a longer stride is better if all other variables, such as stride rate, are held fixed.

Just wow... wrote:

wow at you wrote:

You're implying that a longer stride is better. But stride length x stride rate = running pace.

Your argument is reductive nonsense.

I'm asserting that a longer stride is better if all other variables, such as stride rate, are held fixed.

Well duh.

You have no idea what you are talking about.

wow at you wrote:

Just wow... wrote:

I'm asserting that a longer stride is better if all other variables, such as stride rate, are held fixed.

Well duh.

You have no idea what you are talking about.

Just wow... wrote:

Tibia for sure. You can extend the tib/fib segment at a much more acute angle relative to the ground (more parallel to the ground)during propulsion (when the leg is behind you), than the femur is capable (can only extend about 10-15 degrees from vertical) when the torso is vertical. This gives advantage if the tibial segment is longer, allowing one to cover more ground per stride than a limb with a short tibia/long femur ratio.

There's a non-sequitur here. You might be sure to cover more ground if both your feet stayed on the ground, but in running you leave the ground and your stride length is determined mainly by your speed.

A longer tibia may, by putting the point of contact farther behind the center of mass at takeoff, contribute to having the next footstrike further ahead; it may increase speed by making the foot move faster at the end of the leg as it swings back; but, on the other hand, it increases the amount of force needed in the hip extensors to drive it backward, and in the other various muscles to oppose gravity when it's on the ground, particularly when it's well behind the body. There is no obvious answer to where these advantages and disadvantages balance out.

leg biomechanics wrote:

its not length but proportional length

but having a greater percentage of tibia length to the leg/persons height is more beneficial (there will be a point where you see diminishing returns if it is too long but it would be so extreme it isnt something you actually see)

for cycling the femur becomes more important

This is one of the reasons I'm a natural on the bike and have never been great as a runner.

Take it to the limit. Imagine an extremely long femur and extremely short tibia and vice-versa.