Silk is popular among the technical textiles manufacturers. In a 200-meter freestyle race, athletes can reach a speed of 6.1 km/h, which requires 290 kilojoules (about 72 calories) of energy to fight their own resistance. To reduce drag, many swimmers even shave their entire bodies. But the study found that even when swimming naked, the resistance was 9 percent greater than in a bathing suit. The nylon swimsuit, introduced in 1950, and the polyurethane swimsuit, introduced in 1976, both helped streamline the body to reduce drag in the water. But the real breakthrough was the shark-skin swimsuit first used by British athletes at the commonwealth games in 1998. The suit, made of teflon fiber, mimics the small, spine-shaped projections that line the shark's skin, making it more efficient at moving water around the body and reducing drag. In October 1999, "sharkskin" swimsuit was officially recognized by fina and was used by Australian swimming star thorpe in the Sydney Olympic Games in 2000. He won the gold medal in the 400-meter freestyle, the silver medal in the 200-meter freestyle and the gold medal in the 4-× 100-meter and 4-× 200-meter freestyle relay.

Phelps' new swimsuit for the Beijing Olympics is the LZRRacer from British Speedo, which sells for $290 to $550. Since its debut in February, LZR Racer wearers have broken 37 world records thanks to the amazing sharkskin.

These latest "shark-skin" suits cling to the skin from shoulder to heel, making them look like superman without a cape. Its primary function is to wrap around areas of the body, such as the breasts and buttocks, that sway in the water to increase resistance, and it takes a lot of time to squeeze yourself into the suit. In addition to reducing drag, they also help keep the swimmer's lower body in a more horizontal position.

Of course, it's one thing to measure the coefficient of friction on the fabric of a bathing suit in a NASA wind tunnel and model the fluid dynamics of a vibrating body. Just a few tenths of a second can determine how many gold MEDALS Phelps wins, but it's hard to measure exactly how much of that is due to his shark-skin suit, because competitive sports are always a mixture of individual talent, training and novelty.

American swimmer Michael Phelps won seven gold MEDALS at the 29th Olympic Games in Beijing, a feat attributed not only to his natural physical strength and hard work, but also to his technical textile "shark-skin" suit.