X-Glide

Arena X-Glide is a swimsuit from the Arena brand, made of pure polyurethane that causes a swimmer to slide through water faster when swimming. One notable example of the efficacy of this suit design is that of Paul Biedermann of Germany who wore the suit in the 2009 World Championships, breaking two world records. The design of the suit covers basically the whole torso and the legs with the impermeable polyurethane, thereby exposing less skin to the water and improving the swimmer's buoyancy and streamlined shape. This significantly reduces the drag a swimmer experiences as he or she moves through the water.

According to Rick Sharp, an exercise physiologist at Iowa State University, "The Speedo team came up with a design that put panels of polyurethane over parts of the body that produce the highest drag. Another part is the suit design: You don't want a suit that traps water as it flows around the swimmer. Yet another innovation is to use material that squeezes and slims down swimmers "so the skin doesn't wobble around as they go through the water." Pieces of fabric were put through wind-tunnel tests to check for drag. Programmers used computational fluid dynamics to model the suits' aerodynamic qualities, as if they were trying to figure out how a brand-new jet will fly. Then, swimmers put the designs to real-world tests in tanks and pools.

Following the incredible results the new Speedo LZR Racer swimsuit produced in the Beijing Olympics (Twenty-three world records were broken by the swimmers who wore LZR Racer suits, compared with only two that were broken by the swimmers who didn't. Speedo said 89 percent of all the medals in swimming, including 94 percent of the gold medals were won by LZR Racer swimmers), Italian swimsuit makers Arena and Jaked responded by both developing suits that one-upped the Speedo by using pure polyurethane.

There was a great deal of controversy in the swimming world surrounding polyurethane swimsuits, and strict rules banning these types of swimsuits in professional swimming were put into place. After Biedermann's wins in the 2009 World Championships, Michael Phelps' trainer (until then, Phelps had held the world record for the 200m freestyle since 2007) suggested that Phelps boycott international swimming competitions until the suit is banned. Biedermann's breaking of both Ian Thorpe's 400m world record as well as Phelps's 200m record have been largely attributed to the superiority in the design of his swimsuit. Michael Phelps speculated that the new rules banning polyurethane will level the playing field once more, stating:

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