Training zones: what are they and how should you use them?

Confused about training zones and heart rates? Here we simplify the minefield that is zone training


Training zones are designed to maximise physiological adaptations to your swim, bike and run efforts, and reduce the chances of injury. In other words, by training at varying intensities, you stimulate different adaptations that are all conducive to optimum triathlon performance, whether it’s more speed, stamina or power.


How many training zones are there?

The number of zones can vary but the five-zone method of training is arguably the benchmark. That’s what we’ve used here (note: the discrepancy between the swim, bike and run ranges is due to the position of the body and major muscle groups that are engaged)…

How to calculate training zones

To calculate training zones you need to first work out what your maximum heart rate is when you are working out at your maximum. In his blog top Ironman coach Joe Friel advises this method;

“To find your LTHR do a 30-minute time trial all by yourself (no training partners and not in a race). Again, it should be done as if it was a race for the entire 30 minutes. But at 10 minutes into the test click the lap button on your heart rate monitor. When done look to see what your average heart rate was for the last 20 minutes. That number is an approximation of your LTHR.”

From here you can then work out the following training zones; 

Zone 1

% of max heart rate (range)

SWIM 50-60%

BIKE 60-65%

RUN 50-60%

Perceived exertion (out of 10, 10 being maximal exertion): RPE 2-4, easy to moderate

Performance benefit(s): Training at this intensity will boost your recovery and prepare you to train in the higher heart rate zones.

Zone 2

% of max heart rate (range)

SWIM 60-70%

BIKE 65-75%

RUN 60-70%

Perceived exertion: RPE 4-5, moderate

Performance benefit(s): Basic cardiovascular training at a good recovery pace. This is the intensity to improve aerobic capacity; in other words, stamina. Your body will get better at oxidising – burning – fat and your muscular fitness will increase along with your capillary density.

Zone 3

% of max heart rate (range)

SWIM 70-80%

BIKE 75-82%

RUN 70-80% of max HR

Perceived exertion: RPE 5-7, moderately hard

Performance benefit(s): Running in zone 3 is especially effective for improving the efficiency of blood circulation in the heart and skeletal muscles. This is the zone in which lactic acid starts building up in your bloodstream. Training in this zone will make moderate efforts easier and improve your efficiency.

Zone 4

SWIM 80-90%

BIKE 82-89%

RUN 80-90% of max HR. When intensity is at an upper limit, to increase speed.

Perceived exertion: RPE 7-9, very difficult

Performance benefit(s): This zone will improve your anaerobic capacity, threshold and speed endurance. Your body will get better at using carbohydrates for energy and you’ll be able to withstand higher levels of lactic acid in your blood for longer.

Zone 5

SWIM: 90-100%

BIKE: 90-100%

RUN: 90-100%

Perceived exertion: RPE 9-10, maximal


Performance benefit(s): Training at maximum (i.e. interval training) will increase your anaerobic and muscular endurance, power and cardiovascular levels.


Best heart rate zones for running

Best heart rate training zones for cycling

The triathlete’s complete guide to heart rate zone training

Going Long: Training Zones