The Fitness level is the way BKOOL calculates your fitness level. The default level for any user is Amateur. There are four main categories, with 10 sport level on each one:
You can find all the information about your fitness level and work zones logging at BKOOL.com and clicking on your name (top right corner) >> Profile. Then click on Fitness Level.
Work zones can be modified while editing your FTP test. However our current sport level (Amateur 5, Active 3, etc) won't change unless you take a new FTP test.