Monday, June 15, 2009

How Beach Volleyball Players Jump!

Playing volleyball on the beach is a fun (albeit tiring) way to spend a day in the sun. For those of us who haven't played in a while, it's always a bit of a shock to realize just how difficult it is to jump on the sand. At first glance, the nets don't look all that high and you think to yourself, "Is this regulation? This looks too easy." But when you make that first attempt at a spike, it's immediately apparent the game isn't as easy as the pros on TV make it out to be.

One study suggests that if you can jump and reach 10 feet in a gym, you can expect to only reach 9 feet on the sand. So why is it so much more difficult to jump in the sand, compared to jumping in a gym? The answer is quite obvious: when jumping on the sand, your feet sink into the ground so there's less of a reaction pushing back on your feet, reducing how high you can elevate. In the gym, the floor does sink in a bit when you push off, but the floorboards spring back to their original position, pushing you off the ground for a nice jump. But sand doesn't have this springlike property; for the most part, it just gives way to the downward force you apply with your feet.

Understanding why it's more difficult to jump in the sand allows us to make some educated changes to our technique that may give us better results (i.e., higher elevation).

  • Take a little hop into a flat-footed position before jumping. The landing from the hop will compact the sand beneath your feet, giving you a stable platform from which to jump. The compacted sand will also increase the sand's reaction force to your push off, and will act a little more like the gym's surface (not a lot, but every bit helps). Landing flat-footed (as opposed to the front parts of your feet) increases the surface area in contact between your feet and the sand, minimizing how far you'll sink into the sand.

  • Get your back and arms into it. Bend at the waist a little, and swing your arms back during the loading phase of the jump. Building up this potential energy is a recommended technique when jumping on any surface, but it's especially important when you can't just rely on getting good push off the ground. Swinging your arms upward during the jump not only helps elevate you off the ground, it also gets your arms into position for a block or spike.

  • Jump upward, not outward. Your body can only produce so much force to propel itself; so if you use some of that force to jump forward, not as much of the force will be used to elevate yourself and you won't be able to reach as high a point during the jump. Again, this is true regardless of what surface you're playing on; but on the sand, where the ability to jump high is really valued, it's that much more important to get as much as you can out of each attempt.

While there's no guarantee you'll be able to elevate as high as the professional beach volleyball players, employing some of these techniques may help you get a little more out of your time on the beach. If you're interested in using video to calculate how high you can jump in the sand, please read our recent posting on that topic:

Below is a highlight video from a beach volleyball tournament in southern California. It's not an ideal video clip, in that the camera doesn't seem to be mounted on tripod, but you can clearly view the concepts described above. Enjoy!

1 comment:

John said...

Thanks for your interesting and nice posting:)

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