THE SIDELINES : Amateur Boxer Sean Lee Dies

COLORADO SPRINGS, Colo. — Sean Lee of Baton Rouge, La., who was entered in the 139-pound competition at the U.S. amateur boxing championships, died Sunday while running.

Lee, 18, was the second boxer in four days to die in Colorado Springs, where the championships begin tonight.

Lee died of cardiac arrest, according to Dr. Deborah Waters, chief medical officer for the U.S. Olympic Committee, who said an autopsy might determine whether an undetected heart defect could have contributed to the death.

Tyrone Smith, Navy’s 147-pound boxing champion who had been stationed in Norfolk, Va., died Thursday after surgery to remove a blood clot caused when he fell off a ring apron at the Ft. Carson boxing gym.