Lou's Aerobic Fitness Center was a fitness center in 1985. It was located in the Courthouse Square of Hill Valley where Lou's Cafe, the Sisters of Mercy Soup Kitchen, and the Palace Saloon used to be located.
When Marty McFly passed the fitness center on October 25, the ladies working out inside seemed to know him; as he rode by on his skateboard and waved, the ladies waved back. A sign outside the center advertised a year's membership for $65.00.
It is unknown if Lou Caruthers still owned the building by 1985, but it is highly unlikely, judging by Lou's age in 1955.