Brown and Newton each posted footage from their day on social media.
"'Ace Boogie,'" Brown said in an Instagram video, referring to Newton by his nickname.
"There is so much juice and swag in one video boy that you don't know what to do with it," Newton said. "Your phone probably leaking right now."
Brown tagged "the Heavyweight Factory" in his posts, which is a gym located near Davie, Fla. He previously tagged the location on social media for offseason workouts with Todd Gurley and members of the University of Miami football team.
Newton and Brown worked with Brown's trainer. They did setup workouts and several other exercises. The video comes after the NFL Network released its annual top 100 players list. Brown ranked No. 2, while Newton came it at No. 25.
Newton, who doesn't have any Instagram posts, said he was waiting on a good time to come back on Instagram. He posted his videos on his story, while trying to keep the details of the workouts "super top secret."
"We working," Newton said. "I had to figure what the ingredients was to the No. 2 juice my dog."
"I cant give you the juice if I ain't got the juice. No. 25 ain't cool. I'm trying to be No. 1."
Newton topped the list in 2016. He ranked No. 44 in 2017 and No. 73 in 2015. The 2015 NFL MVP ranked No. 24 in 2014.
The Steelers and Panthers face off on Nov. 8 in Pittsburgh.