What’s the difference between fartlek, tempo and interval runs?

Running is a simple sport, but we’ll admit that it does come with some jargon – and that’s especially the case when we’re talking about the many different types of runs that you can do.

While easy runs and long runs are perhaps a little more self-explanatory, what do we mean when we say ‘fartlek’? How does a ‘tempo run’ fit into the equation? And how do ‘intervals’ differ from everything else?

When we reach the faster-paced runs in our training plan, it can be difficult to understand what they mean, what makes them unique and how you should even go about doing them. So, to clue you up on the ins and outs of speed sessions, here’s our fast guide to fast runs.

What are they?

The word ‘fartlek’ is actually Swedish for ‘speed play’ – and having fun with speed is exactly what this workout is all about. Developed in the 1930s by Swedish Olympian Gösta Holmér, fartlek runs are relatively unstructured and intersperse easy efforts with moderate to hard efforts, defined by markers that are on your terms.

Once you’ve completed a warm-up, play around with speed by running at faster efforts for short periods of time before dialling back to easier efforts to recover. Although most people choose to run fartleks to time, like ‘three minutes fast, then two minutes slow’, you can get imaginative and ‘run fast to the next tree’, or similar.

Fartlek runs are fun to do with a group, as you can alternate the leader and mix up the pace and time. What’s more, you can reap the mental benefits of being pushed by your friends through an unpredictable workout. The goal is to keep it free-flowing – so that you’re untethered to a running watch or a plan – and to run at harder efforts rather than a specific pace. Fartlek runs can be a great option during the winter months, too, as the non-stop aspect means that there’s no waiting around in the cold.

Why do they work?

Fartlek runs are stress-free workouts that help to improve your mind-body awareness, mental strength and stamina.

What are they?

Tempo workouts are like a sandwich. The warm-up and cooldown sections are the bread, while your filling is a run that sees you work slightly above your anaerobic threshold.

Your anaerobic threshold is the point at which your body shifts to using more glycogen for energy and equates to an effort that is just outside your comfort zone – you can hear your breathing, but you’re not gasping for air. If you can talk easily, you’re below the tempo zone and if you can’t talk at all, you’re above it. Your effort level for a tempo run should be somewhere in the middle, where you can talk in broken words.

Pace is not an effective measurement for tempo workouts, since many variables, like heat, wind, fatigue and terrain, can affect your pace. Instead, you should judge the effectiveness of a tempo run by your rate of perceived exertion, which should be about seven out of 10.

In terms of duration, tempo runs tend to last within the region of 20 to 40 minutes, although they can be broken up into shorter chunks. For example, you could run 2 x 10 minutes at tempo effort, with two minutes of jogging in between.

Why do they work?

Tempo runs help to increase your lactate threshold, enabling you to run faster at an easier effort. They also boost your focus and mental strength and are great for race simulation.

What are they?

Interval runs involve short, intense efforts followed by periods of recovery. For example, after a warm-up, you would run, say, two minutes at a hard effort, followed by two to three minutes of easy jogging or walking to catch your breath. Unlike tempo workouts, you’re running above your red line and at an effort where you are reaching hard for air and counting the seconds until you can stop – it is a controlled, fast effort followed by a genuinely easy jog.

Intervals can be run based on time or distance – it’s up to you – and either be extremely short or relatively long. Classic interval sessions include 12 x 400m at 5K pace, with 400m of easy jogging between repetitions, and 3 x 6 minutes at 5K pace, with 2 minutes of easy jogging between repetitions.

The secret is in the recovery, as patience and discipline while you’re running easy allows you to run the next interval strong and finish the entire workout feeling fatigued but not completely spent. As with rest, your body adapts and gets stronger during the recovery blocks.

Why do they work?

A win-win type of workout, intervals improve your running form and economy, endurance, mind-body coordination and motivation.