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Human running speed of 35-40 mph may be biologically possible

blog.smu.edu

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Re: Human running speed of 35-40 mph may be biologically possible

#11

Post by ForHackernews »

faitswulff wrote: post #4

> "Despite how large the running forces can be, we found that the limbs are capable of applying much greater ground forces than those present during top-speed forward running.” Correct me if I'm wrong, but if they extrapolated this from one-legged hops, which put all of your weight on a single leg, isn't that more akin to measuring the ground force from jumping than it is to running?

> isn't that more akin to measuring the ground force from jumping than it is to running?

The point is that the limiting factor is not how much force the limb can exert, and that's what was demonstrated by the one-leg hopping.

Re: Human running speed of 35-40 mph may be biologically possible

#12

Post by ForHackernews »

IvyMike wrote: post #10

I've always been curious: in an enclosed stadium on the moon, would humans run the 100 yard dash faster or slower? I think the first reaction people have is "faster, since you weigh less". But I think the answer is slower, because you would actually be near-floating and contact the ground less. I got into a fight with people on ask.metafilter when I asked this same question, so I had to let it go. But still I hope so…

Who cares about sprinting, I can't wait for the lunar pole vault.

Re: Human running speed of 35-40 mph may be biologically possible

#13

Post by xivzgrev »

faitswulff wrote: post #4

> "Despite how large the running forces can be, we found that the limbs are capable of applying much greater ground forces than those present during top-speed forward running.” Correct me if I'm wrong, but if they extrapolated this from one-legged hops, which put all of your weight on a single leg, isn't that more akin to measuring the ground force from jumping than it is to running?

Yea that was my read too. Of course you have more force on one leg - all your weight is on it and there's less forward momentum.

If you could get all that force into running stance...that's like saying michael jordan has a great vertical. If a runner could apply that same vertical while running top speed, he could leap really far.

Re: Human running speed of 35-40 mph may be biologically possible

#14

Post by [deleted] »

IvyMike wrote: post #10

I've always been curious: in an enclosed stadium on the moon, would humans run the 100 yard dash faster or slower? I think the first reaction people have is "faster, since you weigh less". But I think the answer is slower, because you would actually be near-floating and contact the ground less. I got into a fight with people on ask.metafilter when I asked this same question, so I had to let it go. But still I hope so…

[deleted]

Re: Human running speed of 35-40 mph may be biologically possible

#15

Post by jcrites »

IvyMike wrote: post #10

I've always been curious: in an enclosed stadium on the moon, would humans run the 100 yard dash faster or slower? I think the first reaction people have is "faster, since you weigh less". But I think the answer is slower, because you would actually be near-floating and contact the ground less. I got into a fight with people on ask.metafilter when I asked this same question, so I had to let it go. But still I hope so…

You would certainly accelerate much more slowly, since the upper limit of acceleration is bounded by your friction with the ground, which is bounded by your weight, i.e., your mass times gravity.

What's not clear is whether you could reach a faster peak speed. I think it would be tough to reach a fast speed since your joints would need to oscillate rapidly in order to push off ground moving as fast. And each time you push off the ground you'd achieve less force, due to the friction thing. To summarize, I think I agree with you that humans will run more slowly in a low-gravity environment.

An interesting parallel question is: under 1.3, 1.5, or 2x gravity, how much more quickly could you run? And what's the optimal gravity for running if it's not 1.0 Earth?

Re: Human running speed of 35-40 mph may be biologically possible

#16

Post by omegant »

jcrites wrote: post #15
IvyMike wrote: post #10

I've always been curious: in an enclosed stadium on the moon, would humans run the 100 yard dash faster or slower? I think the first reaction people have is "faster, since you weigh less". But I think the answer is slower, because you would actually be near-floating and contact the ground less. I got into a fight with people on ask.metafilter when I asked this same question, so I had to let it go. But still I hope so…

You would certainly accelerate much more slowly, since the upper limit of acceleration is bounded by your friction with the ground, which is bounded by your weight, i.e., your mass times gravity. What's not clear is whether you could reach a faster peak speed. I think it would be tough to reach a fast speed since your joints would need to oscillate rapidly in order to push off ground moving as fast. And each time you…

Would a 2x gravity be similar to running with a 100 pounds backpack? Then I guess it's going to be substantially slower than 1G running.

Re: Human running speed of 35-40 mph may be biologically possible

#17

Post by recursive »

omegant wrote: post #16
jcrites wrote: post #15

Earlier quoted context omitted.

You would certainly accelerate much more slowly, since the upper limit of acceleration is bounded by your friction with the ground, which is bounded by your weight, i.e., your mass times gravity. What's not clear is whether you could reach a faster peak speed. I think it would be tough to reach a fast speed since your joints would need to oscillate rapidly in order to push off ground moving as fast. And each time you…

Would a 2x gravity be similar to running with a 100 pounds backpack? Then I guess it's going to be substantially slower than 1G running.

No. The runner still has the same mass, so accelerating takes the same amount of energy as 1x gravity. It's like shifting to a higher gear on your bike.

Re: Human running speed of 35-40 mph may be biologically possible

#19

Post by ck2 »

Wind resistance has to be a factor after 25mph, I mean it is on my electric bicycle.

And holy cow, even 25mph is crazy fast, 35? If you tripped and fell at 35-40mph you could seriously injure yourself.

I think I have a good question for the xkcd q&a site: how fast could Usain Bolt run on the moon (ignoring the oxygen problem).

Ah I see someone beat me to the moon problem. Here's another thought, without strong gravity to help return mass to the ground, running is probably much harder.

Re: Human running speed of 35-40 mph may be biologically possible

#20

Post by crystaln »

recursive wrote: post #17
omegant wrote: post #16

Earlier quoted context omitted.

Would a 2x gravity be similar to running with a 100 pounds backpack? Then I guess it's going to be substantially slower than 1G running.

No. The runner still has the same mass, so accelerating takes the same amount of energy as 1x gravity. It's like shifting to a higher gear on your bike.

Not exactly. Horizontal acceleration takes the same amount of energy. The mass of the body must also be supported upon landing, which obviously takes more energy with more gravity.
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