The triathlete’s complete guide to heart-rate zone training

When people typically make their first foray into triathlon, motivation is high while fitness is low. It’s a combination that means large gains can be made in a relatively short period, which helps to embed the philosophy that hard work pays dividends.

But while it’s true to an extent, those who stick with endurance sport soon learn a harsh lesson: tri life isn’t fair. The ‘go hard or go home’ approach might sound productive, but increasing your effort doesn’t automatically equate to increased improvement.

The fitter your get, the smaller the margins for improvement become, so measuring and understanding your effort is paramount – not only for reaping the benefits of training but also for controlling fatigue.

It’s time to enter the world of training zones.

What are heart-rate zones?

If you’ve ever spoken to other triathletes or picked up a copy of 220, you’ll have heard or seen terminology along the lines of ‘2hr bike, zone 1’ or ‘60min run, zone 2’.

The prescribed zones are there to help athletes understand the effort required for the session yet can bamboozle even the most ardent multisport scholar. But the zone system really isn’t that complicated.

“Zones simply define the target effort and allow you to assess that effort through monitoring,” says coach Joe Beer.

Training zones are inextricably linked to heart rate. The harder you push, the faster your blood is pumped and although you can base your training on perceived effort, it’s difficult to control precisely as all too often ego gets in the way.

“Elite athletes might do a lot of training on feel because they’re very attuned to their bodies but lots of age-groupers say they’re going to train steady and find they can’t hold back,” Beer continues. “Heart rate is the best measure. It’s the same principle as a car’s tachometer – it shows you how fast your motor is ‘revving’.”

How to understand the different heart-rate zones

Measuring your heart rate without understanding leaves us no further forward, though.

And it was this that led physiologist Stephen Seiler to study the training and performance characteristics of 21 Norwegian international-level rowers using retrospective heart rate data from 1970-2001.

Seiler noted the rowers’ maximal oxygen uptake (VO2max) increased 12% and their 6min rowing performance increased by almost 10% thanks to increasing their base training from 30 to 50 hours a month, and decreasing their race pace work from 23 to seven hours a month.

His findings suggested that training long and slow could pay dividends.

Yet even if we accept our workouts should be split into zones based on heart rate ranges, how many zones do we need and how should we divide our time between them?

Delving into the internet provides a muddled selection of answers. There are many proponents of five, six, seven and even eight zone systems with fluctuating upper and lower limits.

Complicating matters further is a wide variety of labels given to these zones, such as recovery, endurance, economy and speed – all of which are nebulous terms without knowing the reasoning behind them.

“There are lots of different ways to subdivide the zones,” Beer adds. “But much of it is nit-picking. For the beginner, suggesting that altering your heart rate by three beats per minute will lead to a big change is untrue.

“Having three zones gives people a base zone, competition zone and high-intensity zone, and there are very different perceptions of effort and physiological changes in each.”

With Joe’s help, here we’ll look at each of these three zones in more detail and prescribe sessions where applicable.

How to calculate your HRmax

A few simple sums will help you set your target effort ranges to train precisely. Beer believes the smartest way to work out your HRmax is to look at the heart rate data you collect from training and races.

The reason being not everyone can push themselves to the limit for the sake of a test so there may be another five beats per minute you didn’t realise you had.

“I like people to build up a spectrum of numbers,” says Joe. “A 20min hard effort will be about 90% of your maximum, so after a while these results pull together to give you a range.

“A simple test if you’re a beginner is to ride while breathing only through your nose and accelerate until you need to open your mouth to get enough oxygen.

‘At which point your heart rate should be around 80% of your HRmax. Divide that number by 80 and multiply the result by 100 to work out what your maximum is.”

Alternatively, you can do 2 x 3min runs at max effort with 2mins easy jogging in between. Take the highest HR reading from the second 3min effort as the max. You should be warmed up and in good health before performing this though.

How to buy heart rate monitors

“Keep it simple,” says Joe Beer. “There’s lots to learn from looking at your HR data but many athletes are confused by the technology. All you need is a device that lets you download the results.”

Heart rate monitors can be picked up from as little as £5 and use various methods of recording your pulse, but most athletes favour devices that use a chest strap that fastens around the sternum.

The data collected by the monitor is displayed (and stored) on a compatible device, sometimes a bike computer or sports watch.

Training in Zone 1

This is defined as less than 80% of HRmax. For example: under 160bpm if your HRmax is 200bpm.

“Most endurance athletes will train in zone one (Z1) for the majority of the time,” says Beer. “If you don’t have a heart rate monitor, just try to hold an effort that allows you to breathe through your nose.”

Z1 is pure aerobic work where you start to gently stress your body. It’s not a place to start competing with your training partners, which is where it can be mentally challenging for beginners.

The effort will often feel far too easy, especially for novices who might find they have to slow down significantly to stay below 80% of the HRmax.

Have faith though, because as your fitness improves, you’ll get more speed for the same effort. That’s how elite triathletes can seem to be training at full throttle the entire time; like the rest of us they’re spending around 80% of their time in Z1, but their Z1 is a lot faster because they’re so fit.

Is there a bottom to Z1? Not once you’re off the couch, believes Beer:

“Effective endurance training can still be done in bike sessions at 55-60% of HRmax. You’re doing more work than you realise.

“When you’re sitting down you burn about 60 calories an hour. If you run at just 5mph, it would be about 600 calories. You’re certainly not going to get overtrained at 55%, but you probably aren’t going to be able to hold it that low either.”

Z1 training can be sustained almost indefinitely but should be appropriate to your race distance.

If you’re going to be competing in a sprint triathlon, a two-hour training ride is going to be about three times as long as the bike leg on race day. So be smart when planning sessions.

Heart-rate zone-one sessions

Swim

Warm-up

6 x 100m front crawl (FC) as 2 lengths swim, 2 kick, 2 pull buoy; 20sec rest interval (RI).

Main set

100/200/300/400/300/200/100 FC. Consistent effort and pace; 10secs

RI every 100m. For example 100 = 10sec RI, 200 = 20sec RI.

Cool-down

8 x 50m. Easy pace, 20sec RI.

Bike

30-60min rollers, focus on keeping in middle 30cm of roller, try to practise the following (in order of difficulty): moving hands from bends, tops, hoods, aerobars, reaching for bottle, drinking from bottle.

Run

Double run in the morning – 45mins really easy, relaxed pace, but fast feet for 30m every 5mins.

Afternoon – 45mins as 15mins easy, 15mins @top of Z1 pace, 15mins relaxed.

Training in Zone 2

This is defined as 80-87% of HRmax. For example: 160-174bpm if your HRmax is 200bpm.

Zone two (Z2) is the competition zone, so if you’re in this range your body thinks it’s racing a sprint or Olympic-distance event. Conversation should be difficult but not impossible.

Don’t be confused though – although your body will be straining, this is still an aerobic effort.

“Sprint is the wrong term,” says Beer. “It’s not a 10sec track dash or 50m freestyle swim; it’s an hour’s worth of effort. You can’t close your mouth and keep going; you have to breathe. Therefore it’s an aerobic event and the aerobic system is the most suitable.”

Z2’s upper limit is your anaerobic threshold where lactic acid starts to accumulate in the bloodstream because it’s being produced faster than your muscles can use it.

Beneath this triathletes simply don’t get the physiological punch of working at high intensity (zone 3) and it’s a place you do not want to be.

“You might spend some time in Z2, if you’re trying to get up to zone three but can’t quite reach it,” says Beer. “You shouldn’t worry about this – it’s far more important to stay out of Z2 if you’re meant to be in Z1.”

But if we get X improvement by staying in Z1, wouldn’t we see X + 1 improvement if we just went up those extra few beats into Z2?

Not so, says Beer. “Push yourself into Z2 and it’s like a physiological speed camera going off,” he says. “There’ll only be a small increase in calorie burning but lactate has risen over 2mmols and stress hormones, such as cortisol, kick in.”

In effect, the damage done and the recovery required outweigh the benefits of a Z2 workout. It’s why we normally feel wiped out for a few days after a race.

Physiologist Stephen Seiler’s research has shown that Z2 is a no-man’s land for training. Rather it’s the range you aim to be in when you compete.

During training, you should be above race pace or under it, so the question is not how long should you train in Z2, but why are you training there at all?

Heart-rate zone-two sessions

The lack of Zone 2 sessions is because it’s not typically a zone to aim for. While there may be pre-season threshold or race-pace practice, or build-up races, the point is to build a base and put a small amount of hard effort on top, which for some may be gym work rather than intervals or short races.

You may move through Zone 2 on the way up to and back down from Zone 3 work, and maybe even drift into it when real-world impact stops you being 100% Zone 1.

However it’s not the best place to be training day in day out.

[Coach Taren Gesell would disagree, however…]

Training in Zone 3

This is defined as over 87% of HRmax. For example: 174bpm and above if your HRmax is 200bpm.

This is where it hurts. Zone three (Z3) is interval and impact training, which can only be performed for short periods because you simply can’t get enough oxygen to sustain it.

You’ll be short of breath, sweating hard and, like a cheetah calculating how long it needs to catch its prey, intuitively knowing the effort is impossible for a long period.

Z3 efforts help you build your speed but they’re a double-edged sword, because they also dramatically increase the risks of injury and excessive fatigue. You need to make sure you’re ready for it before you step into Z3.

“If you stayed in Z1 for all of your training, you’d still fulfil 90% of your endurance potential,” says Beer.

“If most triathletes realised how effective base training was, they could ease up and leave themselves fresh for the real top-end efforts. Beginners don’t need to add in much high-intensity work.”

Many coaches work on the 80% easy, 20% hard philosophy, but some of that 20% can actually be strength work.

And while it may not show in heart rate terms, lifting weights is working muscles in a high-intensity manner using the same anaerobic system that goes to work when you’re sprinting.

In fact, when crunching the data, Beer finds it’s rare for the athletes he trains to do much more than 10% of training above Z1.

A sample Z3 session could be 6 x 5min efforts on the turbo trainer or 4 x 1-mile reps on the track. But while Z3 efforts comprise the minority of your training volume they do need to be repeated frequently.

Heart-rate zone-three sessions

Swim

Warm-up

8 x 50m as 25 pull/25 kick alternating with 25 FC/25 choice of drill; 20secs rest interval (RI).

Build set

8 x 25m @90% of max pace. Start with 30secs RI (#1-4) then drop to 20secs RI for #5-8.

Speed set

8 x 25m @95% of max pace. These should be faster than the first set.

Blitz set

8 x 25m @95% of max pace, but with just 10sec RI inbetween. 50m time-trial to aid recovery.

Cool-down

10 x 50m. Mix of bilateral, catch-up and choice of drill.

Bike

Warm-up

20mins, low to high Z1 over moderate terrain.

Main set

6 x [4mins @10-mile time-trial effort, 87-90% HRmax, in aero position, with 2-4mins recovery easy between].

Cool-down

10mins easy spin.

Run

Warm-up

10mins really easy relaxed pace.

Main set

4 x (5mins @10km pace + 2mins jogging RI).

Cool-down

Relaxed jog, ideally some on the turbo.

Top image credit: Jonny Gawler