Sylvia has found her best success at the Half Marathon distance, where she won the 2001 National Championships. She was runner up in 2000. Those results put her on the US National team at the 2001 IAAF World Half Marathon Championships. She had further Half Marathon victories in the Austin Half Marathon and the America's Finest City Half Marathon. She set her personal record of 2:33:47 in the Marathon at the New York City Marathon in 2002. Along with a 2:36:38 at the Los Angeles Marathon, that brought her to number 4 on the US rankings that year. She also holds the course record at the 3M Half Marathon. 2003 New York Marathon 2:33.10 First American 10th, 3M Half Marathon 2004 P.R. 1:09.51 First overall