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Heart rate training. Part 2: How to use your zones and optimise your training

02-Oct-18

Last updated: 03-Oct-18

By James Eacott

Last month, I suggested many of us could improve our ultra performance by utilising heart rate zones to optimise your training. I explained how to set your zones but, once you’ve done this, how do you use them to improve your training?

That’s what this article is all about.

But first, let’s remind ourselves of the theoretical zones we set last time.

Zone Zone name LTHR % Bottom of zone Top of zone
Zone 1 Active recovery Less than 85% 115 128
Zone 2 Endurance 85-89% 128 135
Zone 3 Tempo 90-94% 135 143
Zone 4 Sub threshold 95-99% 143 149
Zone 5 Super threshold 100-102% 149 153


You may have seen other ranges, which include four or even up to seven zones. Four I believe is too few, while seven over-complicates things.

Hence why I like to use five!

Description of the zones

Zone 1 – Active recovery

Although Z1 is referred to as Active Recovery, don’t mistake this zone as purely for recovery purposes. I regularly prescribe - and use myself – training in the upper half of Z1 because it’s a great place for logging low-impact miles.

It’s also the key zone to becoming a fat burning machine.

Running in Z1 does not demand a lot of energy, so your body will save its carbohydrate stores and burn fat instead. The more accustomed to burning fat your body becomes, the better it gets at it and the HR at which you metabolise fat gradually increases.

Utilising fat for fuel is ideal for ultra runners who perform best when supplied with a constant, stable source of energy.

Z1 is the perfect spot for fasted runs too.

Running in Z1 is mentally easy. We push ourselves enough just by participating in this sport, so having sessions that are not mentally or physically taxing is crucial for consistent training.

Put a podcast on, let your mind wander and tap out the easy miles.

Zone 2 – Endurance

This will become a familiar place on your long endurance runs. You should be comfortable running in

Z2 – it’ll form the largest proportion of your training. You’re providing enough stress on your heart and lungs to ensure they become stronger and more efficient, and you’re running hard enough that your muscular-skeletal system is having to work and strengthen.

But beware. Z2 is the easiest zone to over-egg.

Pay attention to the upper end of the zone and focus on keeping under the ceiling.

It may feel too easy at first, but if you’re going to invest in HR training then I’d encourage you to trust in the process and go with it.

Zone 3 – Tempo

Things start getting a little uncomfortable here, certainly in the upper end of Z3.

Tempo efforts are often described as uncomfortably comfortable. They’re manageable, but you’re quite keen for them to stop! They’re great for improving blood circulation as well as strengthening your muscular skeletal system and mental focus too.

It’ll make your Z2 pace feel easier (and will, over time, lower your heart rate at a given speed) and increase your ability to clear lactate from your system.

They never get easier, you just get faster!

Example tempo session progression over four weeks:

  • 3 x 5 minutes at tempo with 5 minutes easy jog recovery
  • 3 x 7 minutes with 3 minutes recovery
  • 3 x 10 minutes with 3 minutes recovery
  • 2 x 12 minutes with 3 minutes recovery

You can continue to progress the tempo duration and reduce the rest until you’re somewhere near 2 x 25 minutes on 5 minutes recovery.

Zone 4 – Sub Threshold

In Z4 you’re really hitting the edges of rather uncomfortable, but by using heart rate you can sit in this zone for up to 20 minutes and really work on stressing your cardio system. Efforts in this range are uncomfortable but used sparingly are good for building heart and lung strength.

The recovery period between these efforts needs to be longer to ensure you perform them with good form.

Example sessions include:

  • 4 x 4 minutes on 4 minutes rest
  • 5 x 5 minutes on 4 minutes rest
  • 3 x 8 minutes on 8 minutes rest

Zone 5 – Super Threshold

Anything over threshold cannot be held for very long but this zone is a useful guide for hard training efforts lasting less than 10 minutes.

Running at this effort will improve your cadence and running economy due to the minimal ground contact time needed to run this fast.

Of course, your heart rate will go above Zone 5 if you push it hard enough, for example in a 5k or maybe even 10k race.

Few ultra runners do them, but I’m a proponent of 20 – 90 second intervals to develop cadence, efficiency and top-end speed. But efforts so short render HR monitoring useless because it takes a couple of minutes for your HR to rise anyway. So, it’s better to use pace to guide these super-short efforts.

Ok, hopefully the difference between the zones is now clear.

How do you apply this knowledge to your training, I hear you ask.

How to use the zones to structure your training

This really depends on what you want to get from HR training.

If you’ve come from a marathon, half marathon or even 10km background then chances are you could do with using HR zones to ensure you’re going slow enough on your easy long runs.

If you’re a diesel engine and have spent years trundling around hour upon hour, then perhaps you could do with using HR training to increase effort levels once or twice per week.

But, speaking to a general audience, here’s what I’d advise:

As ultra runners, I’d encourage about 80% of your training to sit in Zones 1 and 2. Training in these zones will develop the physiological aspects of your fitness most appropriate to ultra running. These zones allow you to accumulate higher mileage and preserve the muscular skeletal system more than high intensity running.

For Zones 1 and 2, HR is key to ensuring you take it easy enough. Easy means easy, but all too often ‘easy’ turns into ‘moderate’. Training in this middle ground is a common cause of injury.

Zone 3 tempo sessions are worth including too, as many ultra runners don’t put themselves in this uncomfortable place very often. They only need to be done once every week or ten days but stretching the cardio system a little harder will reap benefits.

Zones 4 and 5 are less relevant but once every couple of weeks consider cranking up the intensity and hitting these numbers to keep your fitness balanced, and your training fresh!

What’s up next

In Part 3, I’ll explain how to evaluate your heart rate training to ensure continual progress and also how to use heart rate in races.

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