During triathlon races, athletes normally wear a bodysuit, also called a trisuit, which is a garment suitable for swimming, cycling and running. The bodysuit is worn in contact with the skin for the entire race and must have particular characteristics of breathability, drying speed, comfort and resistance.
Most of the suits on the market today are made with special technical fabrics that provide a 'compression' effect, that is, they wrap the muscles in order to minimize vibrations and improve their performance and at the same time ensure excellent breathability that allows the triathlete to stay dry during the effort. Many Trisuits are equipped with seat pads that make the bike phase comfortable but that do not constitute an impediment during swimming and running and that are designed to dry immediately after swimming.
As an alternative to the trisuit, some athletes prefer a combination of shorts and a singlet with similar characteristics to the trisuit. In general, however, the trisuit is preferred in competition, while the singlet and shorts are used more often in training.
If a wetsuit is used during the swim to improve buoyancy and thermal protection, it is worn over the Trisuit and removed by the athlete during T1, i.e. during the swim-bike change. The wetsuit is optional when the water temperature allows for comfortable racing without additional protection, but becomes mandatory in cold water competitions. The race judge decides whether the wetsuit is mandatory, optional or prohibited. Wetsuits ensure maximum thermal protection and buoyancy and are made of fairly thick neoprene, from 2 to 5 millimeters.
In some races, such as the Ironman that are held in warm waters, when it is possible to change between one leg and the next, some athletes use body suits without a pad made of fabrics similar to those of racing suits. These garments called triathlon suits or 'swim skins' are thinner than wetsuits and are made of water-repellent fabrics. Triathlon suits are less popular than wetsuits as they guarantee glide but do not offer thermal protection and are used by the most demanding athletes for 'fast' races.