At the Beijing Olympics, 25 new swimming world records were set; the only Olympics at which more records were broken was in 1976, when goggles were used for the first time. At this year’s Olympics, in addition to U.S. phenomenon Michael Phelps, a new technology has been under the spotlight: Speedo’s LZR Racer supersuit. Not only does this suit have a futuristic, spacesuit-like appearance, but it also enabled astounding performances by swimmers who wore it. Since its launch in February of this year, swimmers wearing the LZR Racer have set 62 world records (as of August 14, 2008). Of the swimmers who set new records in Beijing, all but one wore the LZR Racer swimsuit.

So what is so special about the LZR Racer? According to Speedo, the suit reduces drag, or water resistance, by 38% compared with an ordinary LYCRA suit. This reduction in drag translates into approximately a 4% increase in speed for swimmers. This increase could mean the difference between a gold and a silver medal in swimming, where even a fraction of a second counts. But how does LZR Racer do it?

### The Technology Behind the Swimsuit

It turns out that there is a lot of science and engineering involved in the development of this supersuit, from the choice of fabrics to the positioning of the seams. For three years, Speedo collaborated with scientists from NASA, universities, and sport institutes, and experimented with over 60 materials. In the end, they came up with a design possessing key improvements from their previous swimsuits that: 1) minimizes drag, 2) maximizes support to the muscles; and 3) does so without constraining motion.

Reducing drag is the name of the game in competitive swimming. This is why swimmers do not wear baggy suits, and why some shave their heads. Reducing drag is important because, in mathematical terms, drag force is proportional to the square of speed, and the power required to overcome this drag is proportional to the cube of speed. This means that swimmers have to spend eight times more energy if they want to double their speed! A swimmer encounters two main components of drag: form drag and skin friction drag. Form drag is due to the shape, or form of the body; streamlining the body reduces form drag. Skin friction drag is caused by the actual contact of water against the surface of the body. This type of friction can be reduced by making the surface that contacts the water smoother. A good swimsuit design should minimize both of these components, and thereby allow swimmers to achieve higher speeds without exerting extra energy or altering their swimming techniques.

The LZR Racer is designed with these considerations in mind. Two important features of the LZR Racer are:

1) The fabric: LZR pulse. LZR Pulse is the new fabric Speedo developed for the LZR Racer. It is an improvement over their FastSkinII (used in the 2004 Olympics), which contains small parallel grooves that emulate a shark’s skin. LZR Pulse consists of very fine microfibers of nylon and spandex in a high-density weave. It is extremely light-weight and water-repellent. It is also highly stretchable: it presses firmly against the body and creates the compression needed to streamline the swimmer’s body to reduce form drag, and to reduce entry of water between the suit and the body which can become a source of drag. The compression also reduces muscle oscillation and skin vibration for more efficient performance without compromising swimmers’ freedom of movement. To put together the LZR Racer suit, Speedo used ultrasonic welding instead of traditional sewing to bond the fabrics, as the high profiles of normal seams act as bumps and induce drag. The suit therefore appears seamless. For the same reason, the zip fastener is made to face toward the body (so that the flat underside of the zip teeth faces externally, whereas the raised teeth face inwardly).

2) Panels and core stabilizers. Conventional competitive swimsuits only use a single layer of fabric with low profile seams to minimize skin friction drag. There are limitations to this approach, however. In general, the greater the surface of the body that is covered with a low drag material, the greater the reduction in skin friction. Unfortunately, low drag materials usually have high tension. Thus a swimsuit made of a single material minimizing skin friction can be too tight, and hinder a swimmer’s movement.

Speedo came up with a solution: instead of a single material, they use composite layers consisting of materials possessing different elastic and surface properties. The base layer of the LZR Racer is the LZR Pulse fabric, which fits the swimmer’s body snugly. Separate panels are then laminated onto the outer surface of this base layer. These panels are made of thin sheets of polyurethane, a more rigid material than the base fabric. Specific locations of the panels are customized to the type of strokes. The panels covering the quadriceps in suits designed for breaststroke, for example, are shorter than those for freestyle, so that the panels do not hinder the mobility of the hip joints for breaststrokes’ leg kicks.

In addition to these panels, an internal core stabilizer – an inner core layer of stretchable fabric bonded to the inner surface of the base layer – is used to tighten the abdomen and the lower back, and is supposed to provide a corset-like grip, which helps to reduce form drag and improve core stability.

### The Criticism: Technological Doping?

Though the LZR Racer has led to impressive results in the swimming world, some people have argued that wearing the suit is technological doping – the suit is more like a “device” that swimmers who can afford it (retail price of the LZR Racer is ~ \$550, and you are supposed to wear it only ten times) wear to improve their performance. Nevertheless, the suit was approved by FINA (the international federation recognized by the International Olympic Committee for administering competition in the aquatic sports) for this year’s Olympics.

There is no doubt that technology will continue contributing to the improvement of athletes’ performances in future competitive sports, and that in all likelihood the line between performance enhancing devices and legitimate clothing will become more obscured. The challenge will be deciding where to draw the line. After all, we wish to see a fair game between athletes based on their athletic prowess and technique, and not a competition between technologies and their respective inventors and sponsors.

— Sindy K. Y. Tang, School of Engineering and Applied Sciences

Description of the LZR Racer by Sports Illustrated:
< http://sportsillustrated.cnn.com/2008/olympics/2008/08/19/lzr.racer.suit/index.html >

Description of the LZR Racer by Textile World:
< http://www.textileworld.com/Articles/2008/May_2008/Departments/QFOM.html >

### Primary Literature:

Speedo’s patents on the LZR Racer suit: US Patent Publication number: US 2008/0141430; US Patent Publication number: US 2008/0141431