by Martin John Trout

In the second part of our guide to speed-work in trail running we looked at Fartlek. Here, in our 3rd part we will look at interval training and how it can be incorporated into training to help us become stronger and faster trail runners.

The four basic types of speed-work are

  • fartlek

  • interval training

  • hill sessions

  • tempo runs

Interval Training

Interval training is similar to Fartlek but it is more structured. The principal aim is the ability to run at a sustained speed, at or around the anaerobic threshold for a period of time.

Why is it beneficial?

By breaking the fast running up into intervals, interspersed with recovery periods, it’s possible to do more work in the required zone while producing less tiredness and stress.

An additional benefit is that of encouraging the body to get better at lactate clearance during the recovery periods.

How is it useful for trail running?

While middle distance track athletes might utilize completely passive recovery periods between their intervals, it would appear more useful for longer distance and trail running athletes to utilize active recoveries. So a series of 2’ interval repeats for example would utilize 1’ recoveries of slow running between each interval.

How long or short should the intervals be?

Intervals can be as short as 30” (seconds) and as long as 8 – 10’ (minutes).

Clearly it is possible to do more of the short intervals than the long intervals. So between 10 to 20 x 1’ intervals, but only 6 or 8 x 4’ intervals would be good examples.

The active recovery time can be manipulated in order to elicit different stimulus, however the shorter intervals such as 30” or 1’ generally utilize recovery periods of the same length – 10 x 1’ fast running with 1’ active recovery. As the intervals become longer the recovery periods can be progressively shortened, for example 6 x 4’ fast running with 2’ active recovery or 4 x 8’ fast running with 3’ active recovery.

In an effective training plan the lengths of the intervals and the recovery periods will be varied in order to elicit a range of adaptations.

How to spice it up?

Play with the structure of the interval session in order to maintain stimulation both physically and mentally with different challenges.


Martin John Trout Martin Trout is an all round Adventurer, an accomplished ultra runner, mountaineer, ski mountaineering instructor and trail running coach at Endurance Training in Progress. He’s been living in Italy since the 1990’s.