Lamback dropped more than five seconds from his qualifying time (1:17.26), setting a world record (1:12.09) in the men’s 100-meter backstroke (S7).
“The race really starts after the turn. You can go out as hard as you want, but if you can’t hold it up, you won’t win,” Lamback said . “I had a good turn and brought it home from there. The gold feels awesome.”
Lamback, 22, won a silver medal on Monday in the 100-meter freestyle and also set a U.S. record in the event.
He still has two more individual events to compete in this week.
He won two bronze medals in the 2004 Paralympics.