Cycling training zones: power and heart rate zones explained

Thresholds, recovery rides, training zones… What does it all mean? Paul Knott investigates further

Cycle science
(Image credit: Future)

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Grand Tour riders know exactly what their power output should be, to the exact watt, at any given moment. Cycling training zones can be used to ensure training sessions are completed correctly, and can also be used in races.

This focus on precision has trickled down to amateur level - with riders using heart rate monitors as well as power meters to reach the desired output.

What are training zones?

Training zones are used to give an athlete a set intensity at which they should be working to during an activity. They may, for example, be completing intervals at 'zone three' for 20 minutes.

Training using zones is important becasue it means that riders can be sure they're pushing hard enough during intervals, that they're racing at a sustainable output for the duration required, and that they're pedalling gently enough on recovery and endurance rides.

Knowing what heart rate or power training zone to use in a time trial helps you produce a sustainable effort

The heart rate and power band for one athlete's 'zone three' will be different to the values given to another rider - so before attempting to train using zones, you'll need to carry out a test to gain either your max heart rate value or 'FTP' power (what you can produce for an hour). These values will be used to set your zones.

How do you set your training zones?

You can establish training zones in a number of ways, whether by riding hard for five-minute intervals before easing off to an easy 10-minute interval, all the way up to blood lactate analysis and planning your training around the thresholds that were found in a lab. However, the two most common measures used for cycling training are heart rate and functional threshold power.

Set your training zones using heart rate

Find your max heart rate to set your cycling training zones

Find your max heart rate to set your cycling training zones

Setting your training zones is based on finding out your maximum heart rate is and, from that, working out the zones. A popular method for finding your maximum heart rate has been to use simple equations, such as 214 minus (0.8 x age) for men or 209 minus (0.9 x age) for women, and the original 220 minus age. However, these methods are not very accurate; recent research and coaching techniques has suggested that this method is very outdated and shouldn’t be relied on.

To ascertain your maximum heart rate accurately, you’ll need to carry out a tough test. Ride four times at maximal effort to failure up a long, steady climb, the idea being that you will hit your maximum heart rate on one of the latter of the four ascents. Once you have found it, you can calculate the percentages from the training zone table accordingly.

Heart rate training zones

Set your training zones using heart rate

Set your training zones using power (Functional Threshold Power)

The traditional method of establishing your power based training zones is to complete a functional threshold power test. This consists of a tough hour-long session, with a 30-minute testing period. It can be completed on an indoor trainer or on the road, though there may be a discrepancy between the two — so it’s best to do both.

If you are completing the test on the road, plan a route that doesn’t have any major junctions so that you won’t have to stop. Despite it not pushing you to your maximum power output, the session should be very hard, with the 30-minute testing period requiring maximum sustainable power throughout.

cycling training zones

Set your cycling training zones for the most effective use of a power meter

It is crucial that you complete the initial 10-minute testing period without recording the power data, as it will allow for a steady state effort to be established and also help gauge your pacing for the rest of the test. The average power value for the 20-minute test, minus five per cent, will give you your functional threshold power (FTP). This can be used to work out training zone percentages.

It’s practical to complete this on the road by yourself, but O’Grady suggests doing it indoors on a Wattbike:

“A test protocol will ideally comprise of a ramped protocol. This involves starting at a low power output, increasing in set duration stages by a certain intensity,” O’Grady explains. “This is favourable over a steady-state, all-out test, as it allows for clearer identification of individual points of physiological change as intensity increases.”

More recently, The Sufferfest (living within Wahoo Systm as of September 28) in conjunction with Neal Henderson (Head of Sports Science at Wahoo Fitness) has raised awareness of the fact that setting zones using FTP can be flawed. This is because some riders may have a gold standard FTP but struggle with five minute and five second power, leaving them unable to hit the prescribed zones. In the same way, a rider may have an excellent sprint and a relatively low FTP, meaning their top end zones are too easy if based on FTP.

The Sufferfest and Wahoo Systm now uses a test called '4DP', or Four Dimensional Power. This has you complete a five second, five minute and 20 minute effort, plus a minute at fatigue. Zones are then calculated using these numbers, so that they are tailored to your strengths and weaknesses as a rider. The only problem is this all takes place within the app, so you'd need to download it to test and enjoy your new zones.

Training specifically with power meters and riding to a certain output isn’t the be-all-end-all of training. It may tell you what power you are producing, but without a heart-rate monitor it won’t indicate the physiological cost. However, heart rate can be affected on a daily basis by hydration, temperature, adrenaline and blood sugar level.

Cycling training zone gold standard: lactate testing

Lactate testing is the gold standard for determining exactly what is going on in the body, but it can be difficult to produce reliable test results. Compared to testing for heart rate and power thresholds, now available to mere mortals, accurate testing for blood lactate is a lot harder to find unless you have a batch of scientists to hand. The test consists of taking blood from a finger stick during a VO2 max test so it can be analysed for its blood lactate concentration.

Yet there is a way of estimating your lactate threshold without hiring out a laboratory to conduct the test. This requires completing a protocol similar to the ‘Functional Threshold Power test’ but being able to record data with a heart-rate monitor rather than a power meter.

Complete a similar 30-minute time trial effort, but only begin recording your heart rate for the final 20 minutes of the sesson. After recording your heart rate for every minute of the testing period, working out the average of these results will give an estimate for your lactate threshold level.

Lactate threshold, for an untrained person, usually coincides with 50-60 per cent of VO2max, ranging up to 85-95 per cent of VO2 max for an elite athlete.

The training zones: when to use them

There are many different theories on the number of zones that should be used and the way they are distributed - but we've used a five zone format.

CW training zones

The chart above shows each zone, what length intervals you should ride in this zone, and what percentage of max heart rate or power FTP you should aim to ride them at. If you've not got access to heart rate or power meter, you can use the 'you can' column - simply assess your ability to talk to work out which zone you're in.

Training by zones has lots of advantages over training without any guidance. However, it requires perseverance and patience. Your data may be affected by outside conditions such as whether you are training with a group of riders, the weather or terrain — which all needs to be factored in.

How to use the training zones

Once you have established your target outputs, you need to understand how and why you are training at those specific levels. One of the many misunderstandings within cycling training is in deciphering the jargon and discovering the difference between thresholds and training zones.

Ciaran O’Grady, sports scientist at Cadence Performance, explains what the term ‘threshold’ means: “There is not just one threshold but many, and they each demarcate a point of change in a person’s physiological response to exercise.

“The terminology used to describe these thresholds varies, and there’s a big inconsistency between scientifically reported thresholds and what the public interpret,” he says.

“Lactate threshold is where the body is no longer able to use predominantly aerobic means of meeting the exercise demands. Secondary to this is the lactate turn-point, [the point at which] blood lactate levels deviate from a steady state during exercise. You can also establish threshold data using expired gas analysis and some other methodologies, and each of those brings in its own terminology.”

Once thresholds for these certain measurements are found, your training zones can then be determined. The Cycling Weekly training zones guide (see table) follows a basic structure of five zones, as O’Grady explains: “In a nutshell, not looking at any needs-analysis or specific client data, zones one, two and three would be endurance work, zones three and four would be tempo/threshold work, and zone five high-intensity interval training.”

cycling training zones

Ride intervals at the right training zones for best effect

Zones do not only relate to how you should feel when riding and how to structure training, but each zone also results in different outcomes for race fitness and physiological adaptations. These training zones are related to the three energy systems the body uses when exercising: oxidative, glycolytic and ATP-PC systems.

These energy systems are employed at different levels of exercise intensity. For example, a zone-five effort mainly uses energy from ATP-PC energy system, which provides a huge amount of energy but only for a short period of time. Compare this to a zone one effort, which requires a lower level of energy maintained over a prolonged period. The energy here is supplied by the oxidative system, burning fat and carbs. There is of course much crossover between these energy systems, as the body switches between energy sources.

Suggested sessions using training zones

As O’Grady explains, zones one and two in the table above would be used mostly for warming up and long endurance rides.

Zone three intervals - at threshold or FTP - would be particularly useful for time trial riders, or those training for longer road racers where they'll need to hold a high heart rate for a sustained period of time, perhaps preparing for a breakaway.

A popular FTP/Threshold session is to warm up for 10-15 minutes, ride one 20 minute effort in zone three, recover for ten minutes before repeating this and cooling down.

Zone four efforts are much shorter - typically two to eight minutes. These would be useful for road racers planning to attack and hold a gap, or for time trial riders looking to increase their FTP figure by working at a higher power. An example session might be riding four sets of five minute intervals, with five minute breaks in between.

Zone five is very hard, and would be considered sprint training. This has obvious benefits for road racers, but might also be used by time trial riders trying to boost their neuromuscular power. Short, sub two minute hill reps would be a good option here, or shorter 10 second busts used to improve sprint power. 

From the expert

Ciaran O’Grady is a University of Kent postgraduate and a sports scientist at Cadence Performance (opens in new tab) in London.

“Once you’ve established thresholds and maximal performances, it is useful to see how they relate to each other. Is one extremely close to the other? This will help to determine what type of training you might look to complete. Couple this with target events, available training time and baseline fitness, and a picture emerges of what training should be completed to target specific adaptations.

“Self-prescription of training can only really get you so far, as there are a lot of processes that are involved in human performance. A coach or sports scientist can identify your individual needs and go about prescribing training targeted to your case. Re-testing is important to check it’s working and adjust your zones to the improvements in your fitness.”

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