If you listen to music while you run, chances are there a few songs that you particularly like, as their tempo perfectly matches your preferred running speed. Wouldn't it be neat if your whole music library consisted of songs like that? Well, that's the idea – or one of them, at least – behind the Cruise Control app. Without changing the pitch of the music, it automatically alters a song's tempo to turn it into a motivational running soundtrack.

Cruise Control was created by biomedical physiologist Max Donelan and PhD candidate Mark Snaterse, at Canada's Simon Fraser University. Compatible with iOS devices, it can operate in one of four modes.

In the already-mentioned Cadence mode, you start by selecting the cadence at which you prefer to run. The app will then automatically select songs with a reasonably close rhythm from your library, and then adjust their tempo to play at that cadence.

Free Run mode is essentially the opposite of Cadence. Using your iDevice's existing sensors, the app determines the cadence at which you're running at any given time, and continuously adjusts the tempo to match – in Cadence, you run to the beat of the music, whereas in Free Run, the beat changes to keep time with you.

Pace mode is similar to Cadence, except that you start by selecting the stride speed that you'd like to reach. The app then monitors your pace and gradually increases the tempo, until you reach that speed.

Finally, there's Heart Rate mode. It's like Pace, except that you're being guided towards a target heart rate as opposed to a running speed. An ANT+ or Bluetooth Smart heart rate monitor is required.

According to Donelan, the non-funny-sounding tempo changes are made possible via high-quality time stretching algorithms. "This process is like the inverse of auto-tune, which changes pitch without changing tempo," he told us. "The end result is we can change the tempo of the music on your phone without any Alvin, Simon and Theodores [The Chipmunks] entering the mix. And, no beat track is required."

Users can also do things such as creating playlists, keeping track of favorite songs, and viewing records of stats from previous runs.

Cruise Control is available on iTunes, for US$4.99.

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