ATHLETES in the ancient Olympics competed in the buff, on the grounds (among other things) that clothes were a hindrance to performance. Modern technology, however, has changed that. In some sports, notably swimming, the right attire can be an enormous boon. Take Speedo's LZR swimsuit, which was introduced in February. Fully 38 of the 42 world swimming records that have been broken since then have fallen to swimmers wearing LZRs. Indeed, some of those records have been claimed by less-than-notable racers, suggesting that the difference lies in the apparel, not the athlete.

To make the LZR, four innovations had to come together. The first is the fabric. The new suit is cut from a densely woven nylon-elastane material that compresses the wearer's body into a hydrodynamic shape but is extremely light. Moreover, there are no sewn seams. Instead, the suit is bonded by ultrasonic welding. Seams act as speed bumps in the water. Ultrasonic welding removes 6% of the drag that would otherwise occur, according to Jason Rance, the head of Aqualab, Speedo's research and development centre in Nottingham, Britain. Compared with Speedo's previous suit, which was used by numerous gold medallists in the 2004 Olympic games, the new material has half the weight yet triple the power to compress the body.

Second, the suit has what Speedo calls an “internal core stabiliser”—like a corset that holds the swimmer's form. As a swimmer tires, his hips hang lower in the water, creating drag. By compressing his torso, the LZR not only lets him go faster, because it maintains a tubular shape, but also allows him to swim longer with less effort. In tests, swimmers wearing the LZR consumed 5% less oxygen for a given level of performance than those wearing normal swimsuits did.

The third innovation, a further drag-reduction measure, is that polyurethane panels have been placed in spots on the suit. This reduces drag by another 24% compared with the previous Speedo model. Fourth, the LZR was designed using a three-dimensional pattern rather than a two-dimensional one. It thus hugs a swimmer's body like a second skin; indeed, when it is not being worn, it does not lie flat but has a shape to it.

The results are a suit that costs $600 and takes 20 minutes to squeeze into, and a widespread belief among swimmers competing in the Beijing Olympics this summer that they will have to wear one or fail. The director of the American team, Mark Schubert, for example, thinks the LZR improves performance by as much as 2%—a huge leap considering that tenths of a second may mark the difference between first and fourth place. Arena, a rival swimsuit maker, called the situation “unprecedented” and, initially, lobbied for a review of the garment rules in an open letter to the sport's governing body, FINA (the Fédération Internationale de Natation). Another maker, TYR Sport, has launched another type of suit altogether. It is suing Speedo's parent company, Warnaco Swimwear, Mr Schubert (for more or less insisting that members of his team wear the LZR) and others on antitrust grounds. The LZR is thus being referred to by some people as high-tech doping on a hanger.

Speedo's success is partly due to a subtle rule “clarification” made by FINA in April. It was this which confirmed that polyurethane areas can be incorporated into racing swimsuits. Other manufacturers complain it is unfair that a revision with sweeping implications took place a few months before the Olympics. Still, they are rushing to bring forward rival products. On June 4th FINA approved new suits by Arena, Adidas and Mizuno, so Speedo's technological lead may not last. In technology as in sport, records are simply there to be broken.