Bit Timer: A Brilliant App That Makes Interval Workouts Easy This iPhone app is so elegantly designed that, while you still won’t want to work out, you’ll really wish that you did.

Repeat Timer can act simply as a stopwatch or countdown timer, but it can also handle intervals. You just set the main timer to whatever you want, then the interval timer to a separate length, and ...

What is interval training and how does it improve your speed? A beginner's guide to interval training and the best interval workouts to try.