Fitness boot camps as outdoor fitness group classes developed independently in Australia in 1991 (Original Bootcamp),[13][14] the United States in the 1990s,[3][7][8][15][nb 1] the United Kingdom in 1999 (British Military Fitness),[16][17][18] and Canada in 2001 (The Original Boot Camp).[19] Outdoor group fitness classes such as these have been growing in popularity ever since and have become a distinct commercial market within the fitness industry.[20][21][22][23]