The Fitness Center at Park Centraal Amsterdam
The fitness center at Park Hotel Amsterdam is mentioned by professional reviewers writing for major publications. Out of 6 reviews that we tracked, 3 referenced the fitness center, like Fodor's, Oyster and Star Service.
Park Centraal Amsterdam 
Fodor's
Oyster
Star Service
Fodor's "If leafy Vondelpark isn’t beckoning you to take an early morning jog, there's also a very well equipped 24-hour fitness center, with Star Trac cardio- and strength-training equipment, as well as free weights, towels, fruit and water, and a personal trainer available on weekdays"
Oyster "Other hotel features include a modern fitness center with personal trainers available (open 24 hours), bike and Vespa rentals, and a bar off the lobby"
Star Service "A modern fitness center features the latest cardio and weightlifting equipment"
