In the late 20th century the term strongman changed to describe one who competes in strength athletics - a more modern eclectic strength competition in which competitors lift rocks, tote refrigerators, pull trains, walk while towing an eighteen wheel truck behind them, etc. The most famous competition of this type is World's Strongest Man and the "World's Strongest Man Super Series", however North American Strongman, Inc. (NAS) holds amateur and other meets throughout the United States.