TRACKSUIT: Most tracksuits have a mesh interior which allows the user to wear them without any undergarment such as underwear. This is much like a bathing suit. Many people wear it for physical exercise sessions. A sauna suit is a specialized form of tracksuit made of a waterproof fabric such as coated nylon or PVC that is designed to make the wearer sweat profusely. Sauna suits are primarily used for temporary weight loss.