Olympian Simpson will never run again after cardiac arrest

Olympic medallist Jenny Simpson says a "chapter has ended" and she will not return to running after having a cardiac arrest.

The 39-year-old American, a former 1500m world champion, was pacing a mile group at a pop-up event in North Carolina in June when she collapsed.

She required CPR and the use of an automated external defibrillator before being transported to UNC Rex Hospital in Raleigh, where she went into cardiac arrest again.

"My heart was severely injured and stunned. My lungs struggled too," Simpson said in an Instagram post, external on Thursday.

"I was diagnosed with a rare inherited heart condition called arrhythmogenic right ventricular cardiomyopathy (ARVC)."

ARVC is a genetic condition in which the proteins that normally hold heart muscle cells together do not work properly.

This can cause heart muscle cells to die and be replaced by fatty tissue and scar tissue.

It causes the walls of the heart chambers to become thin and stretched, and the heart cannot pump blood around the body properly.

"My future is an incredible gift. It's hopeful, and it will continue to have great purpose," Simpson said.

"But my diagnosis also means it would be dangerous for me to return to running. That chapter has ended. Thankfully, my story hasn't."

Simpson won 1500m gold at the 2011 World Championships and bronze at the 2016 Olympic Games in Rio, and retired from competitive racing at the end of the 2024 season.

"I'm profoundly grateful that I got to have the career I did," added Simpson, who also won silver medals in the 1500m at the 2013 and 2017 World Championships.

"I experienced everything - from the trenches of training to standing on the top of the podium while our national anthem filled the stadium."