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Author Topic: What/What muscle(s) make you run fast?  (Read 4174 times)

Simulated

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What/What muscle(s) make you run fast?
« on: 28/09/2007 10:28:35 »
Just wondering. Cuz I'm a skinny little kid and I can run really really fast. Just ask Ben.

another_someone

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What/What muscle(s) make you run fast?
« Reply #1 on: 28/09/2007 17:39:17 »
Just wondering. Cuz I'm a skinny little kid and I can run really really fast. Just ask Ben.

Not surprising.  Muscles increase as the square of your size, while weight increases as the cube of your size; so the larger you are, the lower your power to weight ratio (which is why an ant can lift 6 times its weight, while a blue whale cannot even carry its own weight out of water).

The main other factor is ofcourse the length of your legs.

Simulated

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What/What muscle(s) make you run fast?
« Reply #2 on: 28/09/2007 21:34:31 »
I shoudln't have said Skinny. I'm 130 pounds, but really skinny at the same time some how.

And i'm 5 foot 8 or 9. so that'd make my legs..how long?

Karen W.

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What/What muscle(s) make you run fast?
« Reply #3 on: 30/09/2007 17:35:26 »
That all depends on how long the rest of your torso is! 5ft 8 or 9  doesn't give enough of your info to tell how long your legs are! LOL. You may have a short torso and loner legs or longer torso and shorter legs, may be half legs and half torso or even the same.. LOL It all depends!LOL

Bored chemist

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What/What muscle(s) make you run fast?
« Reply #4 on: 30/09/2007 18:15:04 »
"And i'm 5 foot 8 or 9. so that'd make my legs..how long?"
Long enough to reach the ground.

If you stay in proportion, muscle mass (and hence it's ability to produce power) will increase as the cube of your height; just the same as your weight. Probably more important is the lack of fat to carry about.

Simulated

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What/What muscle(s) make you run fast?
« Reply #5 on: 30/09/2007 22:42:25 »
Oh I see

another_someone

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What/What muscle(s) make you run fast?
« Reply #6 on: 30/09/2007 23:10:36 »
If you stay in proportion, muscle mass (and hence it's ability to produce power) will increase as the cube of your height; just the same as your weight. Probably more important is the lack of fat to carry about.

http://www.ftexploring.com/think/superbugs_p2.html
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   Are ants incredibly super strong? Would they be able to toss trucks around like volley balls if they were our size? What if we could shrink down to ant size? Say about 6.4 millimeters (1/4 of an inch for the metrically challenged) tall? How strong would we be compared to the mighty ant?

     And while we're at it, wasn't there always some little guy in PE class that could do 200 pushups and 30 pullups? The big guys, even the strong fast athletic big guys, just aren't usually the pull-up champions, are they? It's almost always the small guys.
  It's true for world class weight lifters too. The smaller people usually lift more with respect to their weight than the big people. It's not better muscles, or a more determined attitude, that helps the little guys, it's just geometry and the way muscles work.

     Like ants their feats are not "super" or even particularly impressive. If they couldn't lift more in proportion to their weight than bigger people, they would be real wimps.

http://www.madsci.org/posts/archives/may99/927263695.Gb.r.html
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Hi Josh-

That's a great question! If you look around on the internet, you'll find numerous references to ants being able to "lift up to 50 times their own weight", but nobody ever explains how, or where that number of "50 times" comes from. I haven't been able to find out where the number came from, but I can tell you why ants can lift so much.

The reason that ants can lift so much is because of scaling: ant muscles are no stronger than human muscles on a pull-for-pull basis, but the small size of ants gives them an advantage on how much muscle force they can produce.

A muscle is basically a bundle of fibres which can contract and create a pulling force- the amount of force produced by a muscle is proportional to the cross sectional area of that bundle of fibres. Consider a bundle of bungee cords- one bungee cord has a small cross sectional area, and doesn't exert much force (you wouldn't jump off a bridge with just one bungee cord to stop you!); a bundle of bungee cords, such as is used for bungee jumping, has a much greater cross sectional area, and exerts much more force (enough force to stop a bungee jumper from hitting the ground!). In human terms, you can think of a human bicep- the bigger the bicep, the larger the cross-sectional area, and the more force (or strength) that can be applied by that bicep. A fellow by the name of Wigglesworth, in 1972, looked at the strength of insect and vertebrate muscles, in terms of force per square centimetre, and found that they both exerted similar forces, so it's not that ant muscles are somehow stronger.

The reason that ants can lift so much is because body size (in terms of volume, which is closely related to mass) increases as a cube of length- while the cross sectional area of muscles increases as the square of length. So, as the size of an organism increases, its mass increases at a much greater rate than the cross-sectional area of its muscles, so those muscles have proportionately more mass to lift.

So, the reason ants can lift so much is because their small size means they don't have a large body mass that they must carry around- they have proportionately more muscle (in terms of that cross-sectional area) that they can use to lift heavy things. Conversely, humans are proportionately more massive, and have less muscle that can be applied to lifting heavy things. The diagram below will explain this:

 You can see that as size increases from big to small, the difference between mass and the amount of force that can be produced by the muscles gets greater and greater. In effect then, we humans have all this extra mass we must lug around, and we have proportionately less muscle to apply force on it, which keeps us from being able to lift as much of our body weight as ants can.

Hope that helps!

Rob Campbell, MAD Scientist



Simulated

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What/What muscle(s) make you run fast?
« Reply #7 on: 01/10/2007 13:25:33 »
Wahoo thanks George for all the info

Bored chemist

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What/What muscle(s) make you run fast?
« Reply #8 on: 01/10/2007 19:17:51 »
Ants are very strong. The question was about speed. Ants are not very fast.

 

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