Jason Kelce has revealed on X that he likely will suffer from CTE, or chronic traumatic encephalopathy, a form of brain damage experienced by post-career football players from repeated head trauma.

Kelce made that revelation during a social media post May 9 suggesting that Secretariat had an enlarged heart, a symptom of being on steroids, and was likely “juiced to the gills,” when the horse won the 1973 Triple Crown.

That got him in trouble with Secretariat fans, including the family that owned the horse, writes Gabriela Carroll for The Philadelphia Inquirer.

One fan on social media declared Kelce’s comments as “objectionable and unfounded” and wrote, “You know who else makes unsubstantiated claims not back up facts? People suffering from CTE.”

Kelce agreed.

“What I’m saying is that it’s completely reasonable to think I have CTE. Even though there is no test to see if I currently have CTE, the evidence suggests I probably do,” he wrote.

“Just like the reality that a lot, if not most of the high-level horses of the 70s and 80s were doping because adequate tests were not available.”

He then questioned in his post why he raised the issue in the first place.

Read more about Kelce’s revelation and response in The Philadelphia Inquirer.