Take the US Navy’s Basic Underwater Demolition/SEAL (BUD/S) course, as anexample. All US Navy personnel, officer and enlisted alike, who desire to become navalcommandos must attend BUD/S, conducted at the Naval Special Warfare Center,Coronado. Just to qualify to attend the course, candidates must swim 500yd (457m)using breast- and/or sidestroke in less than 12 minutes 30 seconds. They are allowed aten-minute rest before having to perform a minimum of 42 push-ups in two minutes,before taking a two-minute break. Next comes at least 50 sit-ups in two minutes, againfollowed by a two-minute rest, and then a minimum of six pull-ups, with no time limit.After resting for ten minutes they have to tackle a 1½-mile (2.4km) run wearing bootsand long pants, in under 11 minutes 30 seconds.