Jenny Simpson, a three-time Olympian and former 1500m world champion, announced her retirement from running after collapsing during a track event in June. Simpson, 39, experienced cardiac arrest while pacing a mile group in North Carolina. She was diagnosed with ARVC, a condition causing dangerous heart rhythms.

Simpson, who won bronze in the 1500m at the 2016 Olympics, was placed on life support due to heart and lung issues. In an Instagram post, she stated it would be dangerous to return to running. She remains connected to the sport through her role at Fleet Feet. Read more culture coverage.

Despite the setback, Simpson expressed gratitude for her life and encouraged others to share positive messages. She represented the U.S. in three Olympics and won multiple world championship medals. Related: Weymouth parkrun Canceled Due to Safety Concerns.

This original Runner World brief is based on reporting from The Guardian Athletics. Visit the source for its complete reporting, context and any later corrections.