From CK Applied Technology:
Gym Executive is a business management database designed specifically for session-based (non-membership) gyms and personal trainers. The software tracks customers, trainers, sessions scheduled, products sold and allows for the creation of invoices for customers and trainers. Trainers can be treated as employees of a gym or as independent contractors. Data can be exported for use with accounting software and spreadsheets. Download the free 50-use demo and start managing all of the daily tasks related to your business using a single software package.