Tempo runs are beneficial for virtually every runner – from milers to marathoners, tempos are nearly ubiquitous.

Of course, they're a staple for longer distance runners training for the marathon and beyond.

If you're not familiar with this type of workout, there are three popular definitions:

1. Comfortably hard. A pace that's faster than "moderate" but not exactly "hard." If you have a high training age and prefer running by feel or perceived effort, this may be the most helpful definition for you.

2. The pace you could race for an hour. For some runners, their tempo pace is similar to or about the same as their 10k pace.

This definition is best used for more advanced runners.

3. 85-90% of maximum heart rate. If you train by heart rate (learn how to calculate your max heart rate here), this is a valuable way to ensure you're in the right range for your tempo run.

More scientifically inclined runners know that tempo workouts are run at or near your lactate threshold. This is the pace at which you're producing the maximum amount of lactate that your body can clear from your muscles and blood stream.

In other words, tempo runs are done at lactate threshold which is the fastest you can still run aerobically.