Spring-supported concrete floating floors are often used as a high-end solution to mitigate noise and vibration disturbances in fitness centers. Suppliers of these floors typically provide impressive sound test results, but information regarding their low-frequency vibration isolation capabilities is scarce. In this study, the authors collected in-situ vibration data from an existing fitness center equipped with a 4-in (102-mm) thick spring-supported concrete floating floor while conducting various activities such as running on a treadmill, dropping a dumbbell, putting down a barbell and slamming a medicine ball on the floor. Frequency measurements revealed that entrapped air led to an increase in the natural frequency of the floating floor. The data demonstrated that floating slab effectively isolated noise and high-frequency vibrations, but was not able to isolate low-frequency vibrations. Additionally, a finite element model of the structure was developed, incorporating the floating floor and the base structural slab. The model was used to simulate treadmill running and weight drops, and calculated vibration levels were presented as heat maps across the entire floor. The model's predictions aligned closely with the actual measurements, demonstrating that vibration analysis based on finite element models is a valuable method to design effective mitigation strategies for fitness centers.