This is the app I'm currently using whenever I run on the treadmill, basically everyday.
You can check out this app in the iTunes store webpage to see a complete list of functions. One of the best thing about this app is the accuracy of its data. Tried, tested & loved.

When you run, it counts the steps you have taken & convert it into distance measurements (km). It even counts your speed and amount of calories burnt. However, when I used it with my treadmill's tracker, there was a slight difference in the distance and speed parameters, but only a slight difference.

I love how it allows you to lock the screen in-app so that you can hold it or put it in your pocket while running without accidentally pressing on the start/stop button. Also, there was once I clicked the home button by accident and an alarm went off to tell me that I have exited the app by accident. You can also build your own gym playlist in the app, so you don't have to re-sync it with iTunes or exit the app to switch songs. So useful, no?

There are options for you to set your daily goals, as well as to key inputs on your body's parameters to track the changes in your body as the weeks progress. It keeps a very nicely graphed record of your body changes & work outs so that you can refer back and compare.

All in all, this is one of the best apps (available in both free & paid versions) and it works for all levels of iOS (so you don't need an iPhone 4 and beyond to use this) even for older versions of the iPod Touch. If you need some pointers on how to start running, see here.

Much love!

xxx