The Dutch take their sports seriously. Amsterdam has about 800 sports clubs. The most popular sports in the Netherlands are football, tennis, (ice)skating and hockey. Step out into the parks and you'll find a number of joggers and walkers of all ages keeping in shape.
Fitness First (http://www.fitnessfirst.com) and David Llyod (www.davidlloyd.nl) are among two international standard, fully- serviced gyms you can find in the city. Below is a listing of some of the main sports and recreational activities you can indulge in when in Amsterdam. http://www.goamsterdam.nl/uk/sports_&_recreation
I see this original post is from 2008, so I thought I'd just update with a site called Gym Nomad (https://www.gymnomad.com) made just for visitors and expats to find fitness facilities over Amsterdam.
Meditation to MMA, 1 day to 8 weeks.
For all tennis fans in Amsterdam!
I have created a website for everyone who is looking for someone to play tennis with in Amsterdam.
I lived in Barcelona for a while where I met a lot of people to play tennis with thanks to a quite similair website, when I got back in Amsterdam I noticed that there was no website like this.
Thats why I created a website for all tennisfans in Amsterdam. The name of the website is http://www.tennisfriends-amsterdam.com,
you dont need to register or something you can just go to the forum and look for people of your own level.
It still needs some promotion so I also created a facebook page : https://www.facebook.com/pages/Tennisfriends-Amsterdam/289809937739443
Please check it out and like the facebook page. :) And hopefully we'll see eachother soon on the tenniscourt!