Complex sentence: Twietmeyer is the only person to have completed the Western States Endurance Run more than 25 times in under 24 hours, a race he has won five times, in 1992,1994-1996, and 1998.
Split into simpler sentences: Twietmeyer is the only person to have completed the Western States Endurance Run more than 25 times in under 24 hours. His five WS100 victories came in 1992,1994-1996, and 1998.