The Gym Barn first appeared in the episode "Rockersize" where Gym Barney was facing some trouble with getting all of the body builders there to work out because of the music he was playing. Grojband went there and said that they would be able to make better music for them. Trina and Mina were also there as exercising with Nick Mallory. Nick mallory was working on his "one ab for week plan" while Trina just came along to gawn at him. Mina also came along to do yoga but she made Trina jealous because of how much better she was at excersizing than her. Barney took them to three elder members of the gym who were the hardest people to put up with at him gym. Grojband ate some super powered energy bars which caused them to jam pack three weeks worth of music into five seconds which gave the old ladies an overdose of testosterone, turning them into three giant "Gorillandmas" who smashed through the wall of the Gym Barn and ran around Peaceville destroying everything. Eventually, Grojband got the Gorillandmas back to the gym again where they played the song "Yesterday" which made them fall asleep. At the end of the episode, Mina got locked in one of her yoga positions of which she ended up left behind in the Gym Barn as it closed down for the day.
The Gym Barn appeared again in the episode "Who Are You" where a body builder was seen lifting a barbell. Corey passed by him and quoted "Meh." which caused the body builder to agree with him and lose interest in working out. It appeared again later in the same episode when Kin, Kon, and Laney took Corey back to the Gym Barn and make him run on a treadmill with the Shoe-Niversities, causing him to excessively care about everything.