In Athens swimmers hope to take advantage of improvements to the full-body swimsuits, introduced at the Sydney games four years ago, that reduce so-called surface friction drag. This effect is caused by water flowing along the surface of the swimmer’s body as he or she moves through the water. Although surface friction drag is a relatively small part of the overall drag experienced by the swimmer, it is large enough to add several hundredths of a second to a competitor’s time and could therefore make a crucial difference in the race for medals.

British company Speedo has developed a swimsuit known as Fastskin, the surface of which is made up of a series of grooves that mimic the dermal denticles – microscopic fin-like structures – found on a shark’s skin. These grooves create microscopic vortices in the water next to the swimmer, thereby disturbing the flow of water along the body and reducing the surface friction drag.

But new studies carried out by Speedo and the Natural History Museum in the past four years have revealed that the texture of a shark’s skin varies across its body to match the flow of water at different parts of its anatomy. The latest version of Fastskin, called FSII, also varies the type and textures of fabric along the swimmer’s body, and is specific to the swimmer’s gender, as well as the type of stroke employed. The outfit is made of rough material around areas where the drag is greatest, such as the chest and buttocks, but makes use of a smoother fabric in regions where the water flows more slowly, such as the inner legs.

To optimize the performance of its FSII suit, Speedo used computational fluid dynamics (CFD) to assess the flow characteristics of numerous combinations of fabrics. It also tested a number of prototype suits on manikins and elite swimmers at a water flume – the equivalent of a swimmers’ treadmill – at the University of Otago in New Zealand.

According to Speedo, the FSII suit reduces surface friction drag by up to 4% compared with the original suit. US swimmer Michael Phelps, who will wear the FSII suit at Athens, will be hoping that this improvement can help him in his quest for seven gold medals. If he succeeds, he will pick up a $1m bonus from Speedo.

In the frame for medals

As with swimming, technology can make all the difference between winning and losing in cycling. For example, two cyclists with the same physical power, identical physique and matching technique travelling at 65 kph could be separated by just a couple of hundredths of a second at the finish line – equivalent to the difference of half a wheel – if the aerodynamic properties of their bikes are different.

The British Cycling team now has what is considered to be the best bike in the world. Designed by Metron Advanced Equipment in the UK, and containing numerous carbon-fibre components manufactured by the Advanced Composites Group, the bike first made its appearance at the Manchester Commonwealth games in 2002. At its heart is a carbon-fibre frame designed using a technique called finite element analysis. This computational method allows the designers to predict the stresses and deformations taking place within the components by breaking a model of the bike down into tens of thousands of individual elements and calculating the forces acting on each element. The designers can then optimize the weight and strength of the bike by distributing the material throughout the frame to match the corresponding variations in the stress.

Recently the designers have enhanced the bike by using CFD to model the complex airflow round it. Previously they had to rely on wind tunnels, but these are expensive to run and require prototypes to be made for each different design under consideration. CFD instead creates a “virtual” wind tunnel that allows the designers to optimize the size and shape of components such as the handlebars and front forks without building numerous prototypes (see figure).

Getting the laser treatment

The development of both Speedo’s swimsuit and the British Cycling bike relied on state-of-the-art laser-scanning systems to create 3D images of either components or the athletes themselves. These scanners generate a 2D fan of laser light that illuminates the object in question at a series of points along its length. At each point the shape of the leading edge of the laser fan matches the profile of the object. This shape is captured by placing a camera at an angle to the laser beam and recording the light reflected from the surface of the object. Joining the profiles together then produces the desired 3D image.

Speedo used a laser scanner belonging to CyberFX, a Hollywood special-effects company that has helped create digital images for films such as the Matrix and Spiderman. Laser scans of a male and female elite swimmer were used to create full-size manikins for tests in the water and to generate the computer models for the CFD studies. The British Cycling team, meanwhile, used the scanner belonging to our group at the University of Sheffield. The scanner was attached to an articulated arm to aid manoeuvrability. It was used to generate 3D models of many of the bike’s components, including its forks, handlebars and even the cyclists’ helmets.

Technology impacts on many sports at the Olympics, not just swimming and cycling. Some say it is cheating, but the use of such technology is a much less invidious aspect of modern sport than performance-enhancing drugs. Strict rules in each sport limit the use of advanced technologies to ensure that competition remains fair. The same cannot be said of advanced pharmaceuticals.