INDIANAPOLIS  The United States Swimming National Championships are serving as a stark reminder that while seasons change, fads fade and fresh faces turn tired, there remains one constant: Michael Phelps.

Phelps raced in two events Wednesday night that were part of his 2004 and 2008 Olympic programs  the 200-meter freestyle and 200-meter butterfly  and won both. In the 200 freestyle, Phelps led from the start against a field that included three other Beijing Olympians. His time of 1 minute 44.23 seconds was well off his world record of 1:42.96.

An hour later, Phelps held off Tyler Clary in the 200 butterfly, an event in which he has held the world record since 2001. He was timed in 1:52.76, missing his world mark by 73-hundredths of a second.

In between Phelps’s swims, Aaron Peirsol regained the 100-meter backstroke world record he had held from 2004 until last week, when the Spaniard Aschwin Wildeboer claimed it with a clocking of 52.38. Peirsol, the two-time defending Olympic champion, took it back with a 51.94.