Arm-swinging riddle is answered | Hacker News Reader

Arm-swinging riddle is answered

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27 pointsepi0Bauqu11 comments

The only problem I have with this experiment is that there is no control for muscle memory.

If you compared the metabolic rate of a piano player playing piano vs. someone who's never touched one before, intuitively the skilled player would outperform the unskilled player. (There are certainly better examples.)

How much experience arm-swinging did those in the arm-swinging group have?

How much experience opposite-swinging did those in the opposite-swinging group have?

How much experience keeping their arms still while walking did those in the still-armed group have?

And is there a certain amount of swing that is most efficient?

I think you misunderstand.

Imagine I wanted to see which arm is better for throwing a ball: right or left.

I choose 1000 subjects and ask 500 of them to throw lefty and 500 to throw righty.

Do you see the issue with this experimental method?

I've always claimed that the arm-swing counters the angular momentum of the legs. Without that you have to expend more energy to prevent your body from twisting. If you walk with your arms constrained that seems to require a "twist" effect from somewhere else.

This could be complete nonsense, of course, but my personal experiments suggest and support it.

> But a trio of specialists from the United States and the Netherlands have put the question to rigorous tests.

This trio clearly did not take Physics 101 at their specialist training location. What you described is a conventional explanation for the arm swinging as I heard it back in high-school over 20 years ago.

In a post a couple of weeks ago on HN, I commented on the difficulty of redesigning the human body. In many contexts, people often suggest "obvious" improvements to the human body, the classic being "let's just get rid of the appendix". But I've get to see a redesign that I can guarantee is actually a good idea.

Here's another example, where some people considered it "common sense" that we'd be better off not swinging our arms around, but, when actually investigated, it turns out that what the human body is actually doing is done for a reason (in the sense that not doing it is less optimal for the body, not in the "intention" sense), and those who thought there was a trivial improvement were wrong.

Just something I thought I'd point out, since this is such a perfect example.

The appendix a popular target just because people aren't entirely sure what it is there for, or weren't for a long time. In recent years we have found more evidence that it has a function in the immune system and in the health and homeostasis of the intestine.

Of course, the relative health of people who have had their appendix removed reinforces this, but the same could be said of a few teeth and kidneys.

We really know very little about the actual purpose and processes of the body. It's an incredibly complex machine. In fact, it is so complex that we currently lack the ability to intelligently design a better one.

How much arm-swinging do speed / race walkers do? Since they compete over long distances and durations, saving energy would be a competitive advantage.

Arm Swing Challenged http://www.funnyassblog.com/random-funny/arm-swing-challenge...

The study, headed by Steven Collins at the University of Michigan at Ann Arbor, says we should give the thumb's-up to arm swinging.

In our easy-calorie society, shouldn't we now give the thumbs-down to arm swinging? (And start telling people to run in corridors)

I learned this from my body work and martial arts studies. Good to have scientific validation...

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