Jenny Simpson, a world champion runner, recently shared that a unique heart condition led to her experiencing cardiac arrest during a race in June, ultimately leading to her decision to retire from running.

On Thursday, in an Instagram announcement, the 39-year-old disclosed that she had been diagnosed with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), a condition that resulted in “dangerous heart rhythms that ultimately led to my heart stopping.”

Due to the diagnosis, Simpson acknowledged the risks associated with returning to running, stating that “that chapter has ended,” but expressed gratitude that her life continues beyond athletics.

The incident occurred while Simpson was pacing a group of girls during a mile run in Raleigh, North Carolina, where she collapsed. Prompt CPR and the use of an automated external defibrillator were administered before she was swiftly transported to the hospital for further treatment.

In response to the situation, Simpson shared her perspective on receiving support, urging well-wishers not to express sympathy but rather to acknowledge their gratitude for her survival, reflecting her own appreciation for being alive.

From 2007 to 2017, Simpson dominated as America’s top women’s 1,500-meter runner, achieving significant milestones such as winning world championships in 2011, securing two second-place finishes, and earning an Olympic bronze medal in Rio during the 2016 games.