I'm an amateur runner who got into the sport during lockdown. Having been bitten by the running bug, I started training for and competing in 10k races, then half-marathons, then finally a marathon. A friend of mine who had completed the Marathon des Sables recommended a type of training called "fartlek" - unstructured interval sessions, with the effort level based upon feel at the time. These inject fun into training and break up the monotony of regular planned workouts. I took his advice and immediately loved the freedom of fartleks. However there was one downside. Spontaneity was difficult to track! Being a stats-obsessed type of runner, I wanted to know for just how long I was jogging, sprinting or walking in each session. Without having planned the session in advance, how could I tell? That's when the idea for Fartlek Interval Trainer came to me. Fartlek Interval Trainer (or FiT for short) tracks your speed throughout your activity, capturing each change of pace as a separate interval. It provides a visual breakdown of the workout by pace segment, giving metrics showing how you performed at each stage. Now you can run freely and see your effort at each stage. FiT also includes support for pre-planned intervals, including Tabata and HIIT. For pre-planned sessions, it tracks actual pace against target, showing when you met or exceeded target pace and when you fell behind. The app is available on iPhone and Apple Watch, with free, subscription and one-time purchase options. I'm continuing to add new features, and would love to hear from other runners on what else they would like to see added to the app.

Fartlek Interval Trainer

The interval auto-detect app.

The interval auto-detect app.