Hey, you, with the scrawny little arms! Yeah, you! Think you have what it takes to be a beefcake like me? Then come on down to Knuckles' Upper-Body-Only Workout Center, 'cause nothing says cool like "mus-cools!"
— Knuckles the Echidna, "Where Have All The Sonics Gone?"
From what has been shown, Knuckles' Upper-Body-Only Workout Center is an outdoor workout center whose exercise equipment are hosted on the beach. As its name implies, it focuses solely on building up the muscles of the upper body.
Owned by fitness celebrity Knuckles the Echidna, Knuckles' Upper-Body-Only Workout Center received recognizable advertisement through street signs and television commercials featuring Knuckles as the spokesperson and/or poster boy.