Seriously though, the 1966 AITC, on page 3-7, recommended 100 psf for Gymnasiums and Dance Halls, but only 75 psf for Bowling Alleys, pool rooms, and similar recreation areas.
Considering the weight of pool tables as compared to workout equipment, and the similar distribution of people, 75 psf might not be a bad value to start with.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask