The LZR Racer also squeezes with what Speedo calls a "core stabilizer"-- a girdle where the material is doubled up. Swimmers use their core muscles to find the posture in the water that helps them float the best, says coach Kipp. "The stabilizer will help you find your balance easier," he says. The stabilizer also reminds swimmers to engage their abdominal muscles during long races, when after 2 to 3 minutes, the muscles tire.
For all its coverage and squeezing, the LZR Racer remains light. Speedo's spandex weighs 100 grams per square meter, four times less than standard swimsuit material [source: Rance]. The spandex is also coated with a water-repellent substance, so it doesn't retain water, making it lighter. Rance emphasizes that the suit doesn't increase buoyancy but also doesn't make swimmers sink.
In simulated race conditions, swimmers swam a start, a 10-meter freestyle and a turn dressed in the LZR Racer and in normal training suits. They swam 4 percent faster and used 5 percent less oxygen in the LZR Racer, says Rance. So presumably, they didn't swim faster because they worked harder. It was because of reduced drag, says Rance.