At the Beach, Learning to Play in the Sand

4.1.1
4.1.1
Tuesday, June 7, 2005

When I run on the beach and a wave chases me up onto the dry sand, I feel like some doomed character from Greek mythology, furiously spinning my legs in vain. My next thought, invariably, is, "Thank God I'm not running from the cops."

Given the season, I decided to learn what happens when we run on particulate matter.

"Your biomechanics change" on soft sand, said Steve Rhyan, an exercise physiologist and registered nurse who trains Navy SEALs and amateur and pro athletes in the San Diego area. Unlike firmer surfaces -- such as asphalt, treadmill belt, a soccer field or even packed wet sand -- soft sand provides no rebound. All the sinking down and pushing back out, Rhyan said, "overloads your musculature." You shorten your stride and struggle to sustain your pace.

How much harder? A 1998 Belgian study concluded that walking on dry sand requires 2.1 to 2.7 times more energy than does walking on a hard surface at the same speed. Running on sand requires 1.6 times more energy than does running on a firm surface.

But don't slump into that chaise lounge just yet: There's a payoff for ambulating on tiny granules of quartz. A 1998 Turkish study of 60 men ages 15 to 21 showed that sand running produced a greater increase in calf circumference over road running and a larger boost in maximum aerobic power (VO2max). The calf size increases came from the muscle overload effect; the VO2jump resulted from the sand group's working harder to keep up with the road runners.

There may be other benefits to oceanside workouts as well. A study published in 2004 by Japanese and Australian researchers compared the impact effects of jumping onto sand vs. wood, concluding that, as one might intuit, training on sand may carry a lower risk of impact injury than training on harder surfaces.

To avoid frustration -- or being caught by the cops -- run or walk on the hard-packed damp sand near the water line. This will allow you to move near your normal pace on a slightly impact-absorbing surface.

On softer sand, Rhyan recommends mimicking your rate of perceived exertion from familiar workouts. "When you change your mode of exercise, always go by feel," he said. The overall intensity should equal that which you experience on other surfaces, as should your total time exercising.

So if you typically jog for 20 minutes, you might walk the beach for 10 minutes and jog the other 10. Or do 15 minutes of one and five minutes of the other.

Rhyan also encourages wearing shoes for beach running, for a few reasons: Our tender feet are unaccustomed to the abuse of barefoot running. Abrasions, blisters and cuts can result. Rhyan said running barefoot "provides no support," particularly nasty for pronators and others who wear orthotics to correct a faulty gait. It can also trigger plantar fasciitis, a persistent injury resulting from a tear in the tissue lining the bottom of our feet. (Yes, Moving Crew investigators are aware of the barefoot running movement, but we'll save that discussion for another day.)

No chat this week, giving you time to put your new beach-running education to work. Join us a week from Thursday. E-mail: move@washpost.com .

-- John Briley


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