What’s the Difference Between Fartlek, Tempo, and Interval Runs?

Here’s a quick breakdown of these three common types of speed workouts.

Interval Workouts

Intervals are short, intense efforts followed by equal or slightly longer recovery time. You can perform intervals in a variety of modalities, but here, we’ll focus on running. For example, after a warmup, run two minutes at a hard effort, followed by two to three minutes of easy jogging or walking to catch your breath. The interval should be performed at an effort in which you’re in the red (think: reaching hard for air, unable to hold a conversation, and counting the seconds until you can stop). It should be a controlled, fast effort followed by a truly easy jog. 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 fatigued but not completely spent. Just like rest, your body adapts and gets stronger in the recovery mode.

Benefits of Intervals: Improved running form and economy, endurance, mind-body coordination, motivation, and fat-burning.

Tempo Runs

Tempo Runs also known as threshold runs, are like an Oreo cookie, with the warmup and cooldown as the cookie, and a run at an effort at—or slightly above—your anaerobic threshold (the marker in which your body shifts to using more glycogen for energy) as the filling. This is the effort level just outside your comfort zone—you can hear your breathing, but you’re not gasping for air. If you can talk easily, you’re not in the tempo zone, and if you can’t talk at all, you’re above the zone. It should be at an effort somewhere in the middle, a “comfortably hard” effort that allows you to talk in broken words and hold that effort for at least 20 minutes. Pace is not really an effective means for running a tempo workout, as there are many variables that can affect pace including heat, wind, fatigue, and terrain. Learn how to find your threshold and run a tempo workout that is spot on every time here.

Benefits of Tempo Runs: Increased lactate threshold to run faster at easier effort levels. Improves focus, race simulation, and mental strength.

Fartlek Runs

Fartleks are not only fun to say out loud, but they're fun to run. Fartlek is the Swedish for "speed play," and that is exactly what this run is all about. Unlike tempo and interval work, fartlek is unstructured and alternates between moderate to hard efforts with easy efforts throughout. After a warmup, you play with speed by running at faster efforts for short periods of time (to that tree, to the sign) followed by easy-effort running to recover. It’s fun in a group setting as you can alternate the leader and mix up the pace and time. And in doing so, you reap the mental benefits of being pushed by your buddies through an unpredictable workout. If you’re running solo, you can use it as a playful way to pass the time by targeting random markers as the finish line for the hard efforts. The goal is to keep it free-flowing so you’re untethered to the watch or a plan, and to run at harder efforts but not a specific pace.