I like and use www.bioexsystems.com – reliable customer service, too. Description of the test, recommendation of the tests given specific client’s needs – I do like how it works. Good luck!
We use BSDI at the wellness centers I am employed. http://www.bsdifitness.com/
Fairly simple and easy to use and generates concise and colorful reports.
It offers a complete check-in system on both the Web and Windows platforms so that you can track and gate attendance at your studio too