I'm with dirty on that one..

Back in the "day", years ago when I was training... we weren't required by the company to be certified. We had in house certifications on weight equipment, cardio classes and such... but that's it. Today, the need for certification has changed some. Most places require their trainers to be certified to work there, or they require getting a certification in a short time frame. Like 30-90 days of getting the job.

Also, a training certification is NOT government regulated. Nor is it regulated by any type of 'official' group or board. So in a nutshell, anyone can give a test and call you certified. There's some 'recognized' certifications out there that most go with, but there is no 'standard'. So you'll want to lean towards someone that's got a degree (from a college) that's centered around physical education or something of the sort. If they do have a degree.. it'll most likely be on the wall to show off. Right next to their personal trainers certs.

Good luck!