Sled runners, also known as blades, are a type of winter sport athlete who use a sled to race down a track of ice. They use their body weight to steer the sled and reach speeds of up to 140 km/h. Sled runners must have excellent balance and control in order to navigate the curves of the track. The sport has been around since the late 19th century and is popular in countries with cold climates such as Canada, Germany, and Switzerland.