Runyan won four gold medals at the 1992 Summer Paralympics in the long jump and the 100, 200, and 400 meter races. She also competed in cycling at those games. She attempted to qualify for the "Able Bodied" Olympics at the 1996 U. S. Olympic Trials, finishing 10th in the Heptathlon. While failing to qualify, she ran the 800 meters in 2:04.60, the Heptathlon record. This success convinced her to try distance running. At the 1996 Paralympics in Atlanta, she took silver in the shot put and gold in the pentathlon.
Her career as a world-class runner in able-bodied events began in 1999 at the Pan American Games, where she won the 1,500-meter race. The next year, she placed eighth in the 1,500-meter in the 2000 Sydney Olympics, making Runyan the first legally blind athlete to compete in the Olympics and the highest finish by an American woman in that event.
By 2001 she won her first of three consecutive 5000 metre National Championships. She also released her autobiography "No Finish Line: My Life As I See It" In 2002 she added the road 5K and 10K National Championships, and married her coach, Matt Lonergan.
She finished as the top American at the 2002 New York Marathon with a time of 2 hours, 27 minutes and 10 seconds to post the second-fastest debut time ever by an American woman. Being an international medalist at 1500 metres and a top major marathon runner is an accomplishment over a wide variety of distances rivaled only by Rod Dixon on the men's side. Medaling at distances as short as 100 metres and diversely explosive events like Shot Put and Long Jump is remarkable versatility.