If there is one type of training that truly makes runners faster, it is interval training. At the same time it is also the most dreaded training. You push yourself to the limit, your lungs burn, your legs go heavy. And yet you come back. Because it works.
Interval training is the controlled alternation of hard effort with active recovery. Not randomly going hard, but consciously and thoughtfully. With the right build-up, the right distances and (perhaps most importantly) the right rest periods.
What exactly is interval training?
With interval training, you run a series of hard blocks, alternating with rest periods of easy jogging or walking. Those hard blocks can range from 10 seconds to 5 minutes, depending on your goal.
There are two main types:
Intensive (shorter) intervals: short blocks at a high pace, with longer rest. Think of 10 x 200 meters or 8 x 400 meters at 5 km pace. Focused on speed and VO2max.
Extensive (longer) intervals: longer blocks at a slightly slower pace, with shorter rests. Think of 5 x 1000 meters or 3 x 2000 meters at 10 km pace. Focused on lactate threshold and specific competition condition.
The shorter and harder the interval, the more rest there is in between. A good rule of thumb: the rest time is at least as long as the effort time for short intervals. For longer intervals, the rest may be shorter.
Why does interval training work?
During intense intervals, your body forces its energy systems in a way that you never achieve during easy running. That triggers strong adaptations:
Your heart becomes more powerful and pumps more blood per beat. Your muscles build new mitochondria: the power plants that convert oxygen into energy. Your body learns to deal better with lactic acid and acidification. Your running technique improves at higher speeds. And your VO2max (= the maximum oxygen absorption capacity) increases.
The result? You can run faster with less effort.
Who is interval training suitable for?
Interval training is not for beginners. Do you have less than six months of running experience? Then first build a solid foundation of zone 2-running and fartlek. Your tendons, joints and muscles need time to get used to the running load. Only then can you safely intensify.
Do you already walk at least three times a week, for at least 30 minutes, without any problems? Then you can carefully start with intervals. Start with one session per week, at low intensity.
How do you build up interval training?
A good interval training always consists of three parts:
1. Warm-up (10-15 minutes): Slowly walk in, possibly followed by running training exercises such as knee lifts, heel-buttocks and some short accelerations. Never go straight into the interval.
2. The intervals: The core of the training. Start conservatively: you should be able to run the last interval as fast as the first. If you leave too quickly, you'll be empty halfway through.
3. Cooling down (10 minutes): Walk slowly. This is not a luxury but a necessity. It helps your body recover faster.
Interval schedules per level
Beginners (first time interval training)
Walk in quietly for 5 minutes → 6 x 1 minute hard (zone 4-5) with 2 minutes of easy jogging in between → 5 minutes walk.
Does this feel too light? First increase the number of repetitions (to 8 or 10), then the intensity.
Advanced (aimed at 10 km)
10 minute walk-in → 5 x 1000 meters at 10km pace, with 90 seconds of easy recovery → 10 minutes walk.
Advanced (aimed at 5 km / speed)
10 minute walk-in → 10 x 400 meters at 5 km pace, with 200 meters of gentle dribbling as recovery → 10 minutes walk.
Alternative ladder (for everyone)
10 minute walk-in → 1-2-3-2-1 minute hard with 1 minute recovery each time → Walk for 10 minutes. The variation in length provides variety and keeps the training mentally fresh.
The role of rest
The rest period is not the break between the "real" training blocks. Rest is part of the training. Too little rest no longer gives you real interval training, but a kind of tempo run in pieces. This is less effective for speed and more taxing for recovery.
A good guideline: after a short, intensive interval, wait until your heart rate has dropped below 130-140 bpm before starting the next one. For longer intervals, the rest may be shorter.
Common mistakes
Start too quickly
The first interval always feels easy. Don't use that feeling as a reason to pick up the pace. The acidification comes later. Consciously run the first two intervals a little slower than you think you can.
Too little rest
Collapsing halfway through a workout is not cool, it is a sign of a poorly calibrated workout. More rest = better quality of the intervals.
Too often per week
Interval training puts a lot of strain on your body. For most runners, once a week is more than enough. Advanced users who want to do interval training twice a week are better off combining this with a shorter, less intensive session.
Do intervals when you're tired
Interval training requires a rested body. Are you tired, sick or did you train hard yesterday? Then choose a quiet endurance run. The quality of your interval is directly dependent on your recovery status.
How do you fit interval training into your weekly schedule?
Never plan your interval training the day after a heavy workout. Give your body at least one rest day or an easy recovery run beforehand. A proven weekly structure for runners who train three times:
- Monday: rest or easy recovery run
- Wednesday: interval training
- Saturday: long run (zone 2)
Do you train more often? Add zone 2 runs in between, no extra intervals.
Frequently asked questions
How long does it take before I see results from interval training?
Should I do intervals on the running track?
Can I combine interval training with strength training?
How do I know if I'm going fast enough during the intervals?
Related training: Tempo run · Fartlek · Hill sprints · Training zones
Bart Vandenbussche is passionate about sport and never shies away from a sporting challenge. He has run several marathons (including sub-3h), is an Iron+Ultra Viking, and currently has the Hyrox bug.
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