Study finds high-tech "shark skin" swimsuits do not affect speed

(CBS News) As with so many Olympic sports, swimmers look for any edge to cut precious tenths of a second off their time. One recent advance in swimming technology was the introduction of "shark skin" swimsuits - tight-fitting suits designed to imitate a shark's unique, sandpaper-like skin. But a recent study from Harvard University concludes that these high-tech suits don't have nearly as much of an effect as Olympians might hope.

George Lauder, a professor of ichthyology, led a study that found shark skin does increase speed - in sharks. The effects on humans are far less noticeable.

"What we have shown conclusively is that the surface properties themselves, which the manufacturer has in the past claimed to be biomimetic, don't do anything for propulsion," Lauder told the Harvard Gazette.

Which is not to say the suits do nothing at all. They may have other benefits outside of their surface texture.

"There are all sorts of effects at work that aren't due to the surface," Lauder said. "Swimmers who wear these suits are squeezed into them extremely tightly, so they are very streamlined. They're so tight they could actually change your circulation and increase the venous return to the body, and they are tailored to make it easier to maintain proper posture even when tired. I'm convinced they work, but it's not because of the surface."

By contrast, the skin on a shark - made up of millions of tiny, tooth-like structures called denticles - has a noticeable effect on the animal's speed.

Lauder and his team discovered that the difference comes from the structure the skin is placed over. Sharks are extremely flexible creatures, and that flexibility allows their skin to reduce drag in the water. When worn by swimmers, the human body's comparative rigidity limits the ability of the shark skin to increase speed.

The study, published in the Journal of Experimental Biology, attached mako and porbeagle shark skin to two robotic arms - one designed to be flexible, the other rigid. The arms were placed in a recirculating water tank. Lauder and his team observed that the flexible arms were able to generate more thrust and less drag than the rigid device.

"I've thought for years that the literature on shark skin needed an upgrade," Lauder told the Harvard Gazette. "Once we got going, I thought it would be fun to look at the Speedo materials, because we don't have a lot of quantitative information on the effect of the surface structure."