HEART RATE TRAINING ZONES
Heart-rate measurement can be a black art; there is no doubt about it. There are many different ways of measuring heart
rate, each with its own benefits and drawbacks. I’ll go through a couple of ideas in this article that should help you
calculate your heart-rate training zones with some degree of accuracy and explain how heart rate training works.
But first…..why do we bother measuring and using heart rate? It’s effectively a way of looking at the effort we’re making so
we know how hard we’re working and, ultimately, how hard we can work.
~~~Use of heart rate training zones lets us make
efficient use of our training time and gives us a measure of improvement. We generally split training zones by looking at
percentage heart rates based on maximum heart rate alone, or maximum and minimum heart rates. The information
below shows the convention of heart rate zones, the uses of that particular zone, and the percentage heart rates used to
bracket these zones (we’ll go into heart rate zone calculation with real numbers later):
Zone Name Training Use
1 Recovery Recovery days/sessions, easy spinning or swimming, very easy running. Possibly used
when injured, over-trained, following a race, etc. Helps the body repair and rejuvenate.
2 Extensive Long endurance workouts to build and maintain base aerobic endurance fitness.
Endurance Exercise at an ‘conversational pace’. 66-70%
3 Intensive Lactic acid production increases, bringing more of the so-called ‘fast-twitch’ muscles into
Endurance play. Frequently used at the end of the base training phase before moving up to the
build phase. 71-75%
4 Threshold Other than extensive endurance, this is the most important zone for the triathlete. Effort
brings you to slightly below (Zone 4) or slightly above (Zone 5a) your lactic threshold—
more on this later on. Effort is now maximally aerobic and your energy systems are
stressed as anaerobic effort and lactic acid production start to limit how long we can
maintain effort. We make big fitness gains in these zones but must be careful to recover
fully after sessions.
~Assuming lactic threshold around 80%,
Zone 4 = 75-80%,
Zone 5a =81-85%.
Adjust according to personal lactic threshold —more later.
5b Anaerobic Interval training is a must as you need the recovery between intense bouts of effort. The
Endurance blood and muscles are full of lactic acid, causing the burning sensation, but the body
starts to learn how to cope with and get rid of these high levels of lactic acid. Big fitness
gains can be made at this level but too much training in this zone is frequently the cause
of overtraining and exhaustion. 86-95%
5c Power Duration at this intensity is measured in seconds, recovery in minutes, effort is explosive,
and injury is common. There is little use for this sort of training for the average multisport
athlete. Avoid injury and spend time at the lower zones instead. 96-100%
The percentages I’ve used here aren’t necessarily the ones you’ll see in every book—some coaches use different
percentages. It’s up to you which ones you use, just change the values as necessary.
However, heart rate measurement is not ideal when used on its own and **we should be aware that there are other
methods of measuring effort:
Borg Scale of Rate of Perceived Effort (RPE)
The Borg Scale of RPE is a scale between 1 and 20, with 1 being no effort at all and 20 being all-out, lung-popping,
maximum effort. It’s a perceived scale, developed by Star Trek Generations fans, and is highly subjective as it’s up to you to
decide how hard you’re working, rather than use a scientific method of measurement to tell you. It can, however, be very
useful in conjunction with heart rate monitors. For example, you’re out on a run and you feel like you’re working really
hard—say, a ‘15’ on the perceived exertion scale; however, a quick look at your heart rate indicates that you’re only working
in your 60-65% recovery zone. Something isn’t right—the conflicting signs show that you’re probably over-trained. The use
of a subjective method (rate of perceived exertion), along with an objective and more scientific method (heart rate or
power) means we have a good way of estimating our work rate and also spotting over-training and illness.
Zone RPE Effort
1 Recovery 6
1 Recovery 7 Very, very light
1 Recovery 8
2 Extensive Endurance 9 Very light
2 Extensive Endurance 10
2 Extensive Endurance 11 Fairly light
3 Intensive Endurance 12
3 Intensive Endurance 13 Somewhat hard
3 Intensive Endurance 14
4 Sub-threshold 15 Hard
5a Threshold 16
5b Anaerobic Endurance 17 Very hard
5b Anaerobic Endurance 18
5c Power 19 Very, very hard
5c Power 20 Ugh, I’ve been sick
As you can see, this is really wishy-washy (‘somewhat hard’’?!?) and cannot be recommended for use on its own. It’s
a very personal system so you have to remember things for yourself and don’t use other people’s ‘effort’.
Steve Trew defines VO2 Max: ‘At a particular work intensity, the oxygen uptake of each individual will reach a
plateau - the maximal oxygen uptake or “VO2 Max”. If the triathlete exercises at a greater intensity, the oxygen
uptake will not increase, because the body is now taking in and using all the oxygen it can.’ The VO2 Max value is
often divided by body weight in kilograms and then expressed as milliliters of oxygen used per kilogram of
bodyweight per minute, or ml/kg/min. As with heart rate, we can define percentages of VO2 Max for training
zones. The problems with using VO2 Max include: you need a gas analyzer to measure it (found in laboratory, not
your garage); different athletes may have very different VO2 Max values for the same performance level, and vice
versa; VO2 Max is limited by genetics, etc. All in all, one for the boffins—by all means, read up on it but it won’t be of
much use to most of us.
Power is an excellent method of measuring exercise effort/intensity and is the current ‘hot training method’, with
professional cyclists in particular. It is normally measured in Watts and, like heart rate and VO2 Max, percentages of
maximum output power can be used to define training zones. Power measurement is immediate and doesn’t have
the delays associated with heart rate (heart rate does not respond instantly to effort). It’s only really on the bike
where we can measure power accurately as there is a conversion of our body’s energy to mechanical energy;
unfortunately, this means that that training with power is limited to the bike. It is, however, easier to measure than
VO2 Max but equipment is still expensive (£400 minimum), especially if you want to be accurate. Because of price, it
still isn’t accessible to the average triathlete and so I won’t go into it much here. If you want to learn more, have a
read of ‘Going Long’ by Joe Friel and Gordo Byrn.
Calculating Training Zones Using Heart Rate
Heart rate is—as it suggests—a measurement of the number of times our heart beats in a minute, hence the measurement is
in ‘beats per minute’ or ’bpm’ - clever, eh? Our muscles need blood and oxygen to work and, when we exercise, they need
more blood and oxygen and our heart beats faster to pump more blood and oxygen round the body. So, the rate at
which the heart beats should give a great indication of how hard we are working—right? Well, pretty much. There are a
number of environmental/physiological conditions that affect heart rate, like temperature, altitude, dehydration, physical
well-being (illness), injury, fatigue, etc. For example, you get up one morning, check your heart rate, and find it’s 5-10 bpm
higher than it normally is—you might feel fine at the time but it’s likely that your body is fighting off infection (pumping
nutrients, white blood cells, protein, etc, round the body to fight infection and repair damage) and you’re likely to feel a
cold or something coming on soon. So we need to be aware of these possible problems and this is where other methods
like ‘rate of perceived exertion’ can complement heart rate.
So, how do we use our heart rate to calculate training zones that we can apply practically to our training programmes?
Convention says that we need to know 2 values: the maximum heart rate and resting heart rate.
Maximum Heart Rate
As it suggests, this is the highest bpm we can manage without dying. It sounds quite melodramatic but measuring
maximum heart rate is actually quite a stressful thing to do and you have to make sure you are well rested and uninjured
before you attempt it. The simplest (and probably most inaccurate method) is to use the formula ‘220 - your age = max
heart rate’. For me, at a sprightly age of 32, it would be ‘220 - 32 = 188 bpm’. So how does that compare with a more
scientifically measured max heart rate? Actually, my maximum is 194 bpm—which isn’t that far off but is still too inaccurate
for our purposes.
I’ll cover 3 methods of measuring maximum heart rate: one on the bike and 2 on the run—these are all called ‘ramp tests’
as they ramp up from easy to exhaustion.
The bike method uses either a bike on a turbo trainer or an ‘ergometer’ bike thingy (the one where you have a stationary
bike set-up with a front flywheel that is braked using a webbing strap around the flywheel circumference). The rider wears
a heart-rate monitor, starts with a 10 minute warm-up, then pedals in a low gear (easy) at about 90-100 rpm. Every 2
minutes a harder gear (or more resistance) is selected. The rider tries to keep this cadence (pedal speed) up until no longer
able to manage it, - ie, exhaustion— and the heart rate at this point should correspond to the maximum.
The running methods are similar. The first is done on a treadmill (can be done on the track): after a good warm-up, a
comfortable pace is found and, like the bike test, we then increase the pace every 1-2 minutes until exhaustion. Be careful
with this one that you don’t fall off the treadmill at the end! An alternative is to find a steep-ish hill that takes about 30
seconds or so to run up. Warm up and then run up the hill quickly 4 times, with a rapid jog back down the hill in between
and no rest at the bottom between each repetition. On the 5th repetition, go as fast as possible and measure heart rate at
the top—you should be chin-strapped at this point!
Maximum heart rate is a bit weird: it doesn’t change that much throughout adult life. It can change slightly but isn’t
generally dependent on fitness. We could now just calculate heart rate training zones by taking percentages of maximum
heart rate. For example, to calculate our Zone 3 heart rate upper and lower limits, we just take 70% of max heart rate for
the lower limit and 75% for the upper limit (for me, it would be 0.70 x 194 = 136, and 0.75 x 194 = 146). This, however,
doesn’t take our resting heart rate into account.
Resting Heart Rate
Right, we now have one half of the data we need but why is resting heart rate important too? Unlike maximum heart rate,
resting heart rate is very dependent upon fitness; generally, the lower the resting heart rate, the more efficient your heart is
and the more blood is pumped for each heart beat. As you get fitter, resting heart rate should get lower so, to make sure
your training zones are accurate, measure resting heart rate every couple of months, and adjust training zones accordingly.
It is rumoured that cyclist Miguel Indurain had a resting heart rate of something daft like 35 bpm - uh? That’s around one
heart beat every couple of seconds! It’s practically clinically dead.
Resting heart rate is a piece of the proverbial to measure. Over a week, measure your heart rate every morning before you
get out of bed. The average of your measurements that week is your resting heart rate. Make sure you don’t have a cold
or anything as this will raise your resting heart rate artificially.
Training Zone Calculation
We can now calculate the heart rate dynamic range (range over which heart rate changes) and the training zones. This
particular method is called the ‘Karvonen Method’, after the guy who invented it: Dr Method. Not really—that was a joke.
Heart rate dynamic range is simple: ‘Max Heart Rate - Minimum Heart Rate = Dynamic Range’
We calculate training zones using a percentage of the dynamic range and then we add the resting heart rate to get the
Value = (Zone Limit % x Dynamic Range) + Resting Heart Rate
For someone with a max heart rate of 195 bpm and a resting heart rate of 45 bpm, Dynamic Range = 195 - 45 = 150, so:
Zone 1 lower limit = (0.60 x 150) + 45 = 90 + 45 = 135 bpm
Zone 1 upper limit = (0.65 x 150) + 45 = 98 + 45 = 143 bpm
Zone 2 lower limit = 145 bpm Zone 3 lower limit = 151 bpm Zone 4 lower limit = 159 bpm
Zone 2 upper limit = 150 bpm Zone 3 upper limit = 158 bpm Zone 4 upper limit = 165 bpm
Zone 5a lower limit = 166 bpm Zone 5b lower limit = 174 bpm Zone 5c lower limit = 189 bpm
Zone 5a upper limit = 173 bpm Zone 5b upper limit = 188 bpm Zone 5c upper limit = 195 bpm
See? It’s pretty easy, really.
We talked about lactic threshold in a previous article on anaerobic and aerobic energy systems but I’ll summarise it again
Lactic acid is a waste product that is produced in the muscles during exercise. The problem is that, as we increase exercise
intensity, the amount of lactic acid produced increases too; below the lactic threshold (also known as the ‘anaerobic
threshold’), the body is able to flush this waste from our muscles and we retain a balance. We eventually get to a point
where the body cannot get rid of the lactic acid fast enough, the balance tips in favour of the lactic acid and we get that
burning sensation in the muscles which eventually stops them contracting properly. Lactic threshold is a key limiter for
performance but is, luckily, very ‘trainable’. Most anaerobic training is designed to raise the lactic threshold so we can
exercise at a higher intensity without being limited by lactic acid.
Typically, lactic threshold is around 80-85% of heart rate (somewhere between 165 and 173 bpm in the above example
calculations) and we need to have an idea of our threshold value so that we can train either slightly above, or slightly
below it in specific lactic threshold training sessions.
There are lots of ways of measuring lactic threshold and I’ll briefly mention 2 methods here:
In the laboratory, lactic acid is measured using blood tests. It is unlikely you’ll have a lab in the garage but this is the next
best thing. The Conconi test uses repeated intervals (running on the track or biking on the turbotrainer) over a set distance
(eg, one lap of the track). Each lap of the track is run slightly faster than the last—ie, increasing the intensity—by, say, one
second. The heart rate is measured over the last quarter of the interval and the speed is calculated from the time and
distance (both known). You then plot a graph of heart rate against speed and, at the lactic/anaerobic threshold, there will
be a ‘knee’ - see diagram. You can do the same by measuring power and plotting power against heart rate. What we get
is a speed or power and an associated heart rate for the lactic threshold. As we get fitter, the threshold values of heart rate
and speed/power will increase. Therefore, we have to measure progress every few months.
Time Trial/Race Method
Easier is the 10 km race test. Wear a heart rate monitor and run a 10 km road race over a fairly flattish course. Use the
‘Average heart rate’ function on the heart rate monitor and that heart rate will be exactly—or very close to—your lactic
threshold. If you don’t want to run it, try a 25 mile bike time trial instead; again, take the average heart rate (see below for
‘sports specificity’ factor). Check the value against the calculations you’ve made above—if it’s miles off, something’s wrong.
Give it a couple of weeks and then do it again.
Heart Rate - Sport Specificity Factor
There’s one slight problem we’ve not discussed yet and it can have a significant impact on your training. Heart-rate
changes with loading and intensity, but loading and intensity also depend on which sport you’re doing.
The Karvonen method I mentioned before is most accurate for running heart-rate training zones and running is probably
the most intense sport, as you have to fully support your own bodyweight on your legs and fight gravity as well as propel
yourself forward. In cycling, unlike running, your bodyweight is mostly supported by the bike and you also have the option
to freewheel, effectively having a rest for a bit, which you can’t do in running. In swimming, the whole body is supported
by the water and, remember, you don’t have to swim uphill against gravity!
This means that your lactic threshold for running—particularly if you come from a running background—will be higher than
it will be for cycling, and even higher than for swimming. If you don’t believe me, try the 10 km running and 25 mile bike
time trial methods of estimating lactic threshold. The threshold value for cycling will be around 5-10 bpm lower than for
There is an easy solution, though: calculate Karvonen values for running and then subtract approx 10 bpm to get heartrate
zones for cycling and about 15 bpm for swimming. This should be good enough to be getting on with but, as you
get more experience, you can adjust values to make sure you are in the correct zones for each sport. It’s also a good
reason to get used to the scale of perceived exertion I spoke about earlier: you can compare your own subjective feeling of
RPE with the heart-rates you are achieving and see if they match up between sports.