runtastic has Runtastic SitUps PRO (iTunes Link) for the iPhone, iPod Touch, iPad in the iTunes App Store for FREE (regularly $1.99) for a limited time.

Flatten your stomach and get those ab muscles to start showing with runtastic SitUps PRO app!

With the runtastic SitUps PRO app you can now achieve this goal. The app is your personal sit-up trainer that uses an easy to follow scientific sports training plan that helps you build strength and see constant improvement.

Unique recognition of your sit-ups: Sit-ups are counted automatically using the accelerometer on your iPhone or iPad.