Avitabile’s first marathon was 34 years ago, and she began competing in triathlons as the sport exploded in the United States in the 1990s. In the only triathlon she couldn’t finish in her career, Avitabile actually did cross the finish line — in an ambulance. It happened at the Sea Gulls Century triathlon in Salisbury, Md., about 10 years ago, when she crashed on the bicycle course.