The Fitness Center at Swissotel Amsterdam
The fitness center at Swissotel Amsterdam is acknowledged by experts. Of the 4 reviews tracked on TripExpert, 2 referenced the fitness center, like Oyster and Star Service.
Swissotel Amsterdam 
Oyster
Star Service
Oyster "The main floor has a small lobby, business center, and bright fitness center, but the narrow setting lacks communal areas and dining options"
Star Service "There is a small but reasonably well-equipped gym on the first floor where guests can look out over Dam Square and listen to music while working out"
