The American women continued their assault on the U.S. record book last night, breaking three marks on the second day of competition at the AAU National Short-Course Swimming Championships at East Los Angeles College.

The U.S. women have set American standards in all five events completed, with two days of competition remaining.

The men also got in on the record spree as Mission Viejo's Jesse Vassallo won his second event of the meet setting an American standard in the 400-yard individual medley of 3:48.24.

Vassallo, 17, is the world champion and world record holder in the 400-meter event. His splits tonight for the race were 52.19 in the butterfly, 56.55 in the backstroke, 1:06.18 for the breaststroke and 53.32 for the freestyle.

Tracy Caulkins, 16, of Nashville Aquatic Club stretched her unbeaten streak in national competition to 12 events and set her third American mark of the meet by winning the 400-yard individual medley in 4:08.09.Caulkins, winner of the 1978 Sullivan Award as the nation's outstanding amateur athlete, broke the mark of 1:11.38 she set at the nationals championships last year in Austin, Tex.

Caulkins won easily over Anna Twedy of Santa Barbara Swim Club, second in 4:15.81. Caulkins swam the butterfly leg in 55.22, backstroke in 1:03.3, breaststroke in 1:12.58 and freestyle in 57.09.

Cynthia Woodhead, 15, of Riverside, Calif., broke the American mark of 1:44.89 she set in the preliminaries of the 200-yard freestyle, blazing to a 1:44.1 to win her fifth national title.

In the men's 200 freestyle, Dave Larsen held off a strong challenge from Florida Aquatic Club teammate Rowdy Gaines to win in 1:36.20. Gaines was a flash behind in 1:36.22.

Starlit Aquatic Club's Brendan McCarthy finished 14th in the 200 freestyle with 1:40.05 after qualifying for the finals in 1:35.25.

Starlit Aquatic Club also finished 11th in the men's 400 medley relay, won by Longhorn Aquatics in 3:18.39. The Starlit quartet of Sam Hewson (52.98) Trent Lyght (57.31), Tom Townsend (49.21) and Sam Jones (43.71) recorded a 3:23.21.