Retired NASCAR driver Dale Earnhardt Jr. said concussion-related nausea returned as he watched a recent practice up close at Martinsville (Va.) Speedway.

Earnhardt went to the track with colleagues from NBC and accompanied Steve Letarte to the inside of turn three, Yahoo Sports reported. Letarte is an NBC Sports color analyst and former NASCAR crew chief.

Being so close to the cars gave him the same feeling of nausea that he had in 2016 while recovering from a concussion, Earnhardt said on his Dale Jr. Download podcast.

Earnhardt had concussions in 2012, the first at a test at Kansas Speedway that he did not divulge. Later that season, he suffered a concussion in a wreck at Talladega (Ala.) Superspeedway. Earnhardt missed the next two races and was treated at the University of Pittsburgh Medical Center.

Concussion-related issues factored heavily into his decision to retire after the 2017 Cup season.

“My doctor explained that my vestibular system had never been in that situation before,” Earnhardt said on last week’s podcast. “And I got to thinking that. Yeah, I had never been down in the corner watching cars practice. Never have. Never been there since I’ve been a kid. Never done that in years, since I’ve been in the car.

“When I was out of the car, I was never standing 25 feet away from them watching practice,” Earnhardt said. “That was a real extreme environment to be in, and it made me trip out. Gave me some symptoms and stuff that reminded me of the illness I had a couple years ago with the head issues.”

In March 2016, Earnhardt said on Twitter that he will donate his brain for concussion research.