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The Leg Bone’s Connected to the Knee Bone/The Left Hemisphere’s Connected to the Right Foot

- August 12, 2008

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If you’re watching the track events in the Olympics, notice that when the sprinters get down into their starting blocks, some of them have their left foot back to push off with and others have their right foot back.

Big deal, eh?

Well, it turns out that it matters. The left-foot-backers are putting themselves at a disadvantage, and if they would only read the Washington Post or, now, The Monkey Cage, they would know better. In a relatively long race, it’s not enough of a disadvantage to matter, but in a short sprint — say, the 100-meters race — it can make, say, a tenth of a second difference. And a tenth of a second difference can be the difference between a gold medal and nothing.

How can this be?

Shankar Vedantam, in the Washington Post, lays it out in non-technical terms, in a summary of an article by Adam Eikenberry and James McAuliffe, forthcoming in Acta Psychologica:

bq. …[T]he right hemisphere of the brain … plays a central role in reaction time, whereas the left hemisphere of the brain plays a larger role in overall movement control. When a task is primarily about reaction speed, people tend to be faster with their left hand because it takes less time for the right hemisphere to “talk to itself” than to tell the left hemisphere to move the right hand or foot.

bq. But when it comes to movement — in the case of sprinters, coming off the blocks and beginning the first step — people tend to be faster with the right hand and foot. That’s because the left hemisphere plays a dominant role in movement generally and moving the right side in particular.

And, contrary to my own initial assumption, which was cued by the fact that I’m left-handed/footed/etc., it’s not a matter of laterality. This effect holds for both righties and lefties.

I’m not sure that any of this really matters to 99.44% of us. But if you’re a sprinter, it certainly does. Presumably it would matter to a cyclist, too: Other factors being equal, you’d want to start with your right foot up so you can more rapidly mash the right pedal down and beat your competitors off the line.

For the full text of the Vedantam article, click here.

[Hat tip to Bruce Dickson]