Bobsledding is a winter Olympic sport where teams of athletes pilot a sled down an ice track at speeds over 80 mph. It originated in the late 1800s in Switzerland as an activity involving racing sleds down snow-covered hills. Modern bobsleds are made of aluminum and steel with metal runners, and races involve teams of 2 or 4 athletes pushing the sled at the start before jumping aboard to navigate the track through turns. Training for bobsledding requires extensive strength and speed work by athletes who may train over 10 hours per day to achieve the skills and fitness needed to compete at the Olympic level.