Ryan Shay‘s autopsy has been completed, and while it does not include an public toxicology report, his father was told that there was no evidence of any drug use. There was evidence of scarring in his heart that could not be attributed to anything specific and could have been caused by anything from childhood pneumonia to previous heart attacks. The official cause of death was has been linked to an irregular heart beat due to an enlarged heart.

Runner’s world has taken a look at various studies of cardiac deaths, comparing the instances of sudden cardiac death in young people to coronary artery death in people in their 40s or older. In the instances of young people, the most common causes of sudden cardiac death are due to genetic abnormalities that are present since birth and severe blows to the chest. Despite young athletes with some sort of heart abnormality being in more danger of dying during exercise, their overall risk of mortality is less if they engage in regular exercise.

As marathoning cardiology expert Paul Thompson, MD, once wryly put it: “If your only goal is to survive the next sixty minutes of your life, then your best strategy is to go to bed… alone. However, if you want to lower your lifetime risk of heart disease, then your best strategy is to fill the next hour with sixty minutes of moderate exercise.”

Ryan died during the men’s Olympic Marathon Trials this past November.

(More information: Runner’s World)