VENTURA, CA -- The sport of running experienced an 8 percent jump in participation from 1998 to 2005 after declining in the early 1990s, according to a recent study from the USA Track and Field’s Road Running Information Center. The center conducted its own research and reviewed studies from the National Sporting Goods Association and American Sports Data for its annual report. In 1998, 35 million reported running at least once, and in 2005, 37.8 million people ran for exercise. The study also found that the frequency of the runs also increased. About 29 people ran at least six times in 2005, and runners who ran at least 100 days a year increased to 11.5 million.