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Home / Training Science Series #9 - A Brief Introduction to Heart-Rate Zone Training

Training Science Series #9 - A Brief Introduction to Heart-Rate Zone Training


This is an article series designed to help further educate my Performance Coaching clients. I am releasing it in this article series to help educate more people to create a life of health and adventure. If you are interested in getting fitter -- irrespective of whether you are a novice or regular athlete -- then please read through this series and learn more about the endurance training process. I welcome you onboard as your performance coach to help guide you to the summit of your athletic potential!

Training Science Series: Why We Focus on Capacity Training…to Eventually Go Really Fast

Part One - Introduction

Part Two - The Utilization Problem

Part Three - Overtraining Syndrome (OTS)

Part Four - Advice for Beginner Runners

Part Five - Aerobic vs Anaerobic Fitness

Part Six - The Aerobic Base - Capacity Training 101

Part Seven - The New Science of Fat Adaptation

Part Eight - Introduction to Training Thresholds

Part Nine - A Brief Introduction to Heart-Rate Zone Training

Part Ten - How to Choose Which Zones to Train in Regularly

Part Eleven - Peaking: When to Enter a High Intensity Training Phase

Part Twelve - Keeping the Ego in Check and Sticking to a Long-Term Plan



Part Nine - A Brief Introduction to Heart-Rate Zone Training


The sports lab is the best place to determine accurately the AT and LT heart-rates. However, you can use the next best thing—testing them with specific workouts. At C2TS Performance Coaching, I get my athletes to run different workout tests to determine their aerobic and anaerobic threshold heart-rates. We regularly retest these heart-rate thresholds, to ensure our training zones are optimised as fitness changes occur. Once we have the heart-rates, we can use maths to calculate the heart-rate zones to be used in training. I use five heart-rate zones (with an added zone for recovery) to help my athletes understand the training intensities they should be applying for their daily workouts. Zone’s 1 and 2 (beneath the AT) are used for aerobic capacity training, while zones 3-4 (above the AT) are used for utilization training. Zone 4 is essentially open-ended up on the upper range to the max HR. Zone 5 (sprint pace) can be lightly used either during capacity or utilization training periods largely for muscular strength training more than anything.

An example below of the zones for an athlete with an AT of 153 and LT of 170bpm:

Figure 9 - Heart Rate Zone Ranges for an Athlete with AT at 153bpm and LT at 170bpm.


Low Intensity Zones for Capacity Training



Very easy effort, >20% lower than the AT heart-rate. This is a relatively easy effort and plays a minor role in improving aerobic fitness, but aids recovery by delivering more blood flow into the muscles. An activity recovery session is always preferred to doing nothing for optimal recovery from hard training. You should always feel better right after or within a few hours of a recovery training session, and definitely should not feel more fatigued from this session.

Zone 1: Recovery and Basic Aerobic Conditioning

Zone 1 is the heart rate range in the zone 10-20% lower than the AT heart-rate. This training zone helps to develop fat metabolism for fuelling, build mitochondrial mass, increase capillary density and other beneficial aerobic adaptations throughout the slow-twitch muscle fibers. It’s heavy application in capacity training prepares the body for greater fatigue resistance and handling the impact loads of future training, helping to offset both fatigue and injury. This zone should be easy enough that you may sometimes feel “guilty” when you are done, because so much was left in the tank. You should be able to keep this pace for several hours or more and easily hold a conversation with someone.

Zone 2: Aerobic Capacity and Endurance: 

Zone 2 is the heart rate range in the zone 1-10% lower than the AT heart-rate. Zone 2 is crucial to endurance performance, and has the greatest impact on raising the AT. The same benefits seen in Zone 1, apply to Zone 2 training, but the added demands encourage greater adaptations. Zone 2 has the purpose of improving lactate clearance capacity by increasing the number of mitochondria to clear lactate mainly in slow twitch muscle fibers as well.1 Zone 2 should feel relatively easy, at least in the beginning, but you should feel as though you have to work if you've been doing this for more than an hour. The speed should feel like a reasonably hard effort where you start breathing heavily. Zone 2 workouts create too much residual fatigue for aerobically efficient athletes, but are a staple in the diet of aerobically deficient ones. The AT heart-rate sits at the top of Zone 2 and the bottom of Zone 3, and this heart-rate is useful for pacing in ultra-endurance race efforts.


High Intensity Zones for Utilization Training

These zones have high energy demands and shift from fat to sugar metabolism. These are used sparingly but have tremendous benefits for increasing fitness rapidly.

Zone 3: Between Aerobic Threshold and Lactate Threshold:

Zone 3 between the two thresholds, is the "Race Pace" zone and is a mixed fat and sugar fuel source zone. This zone has an immensely powerful training effect, and is why novices end up doing so much utilization training in this zone to make training time more efficient. The regular overuse of this training zone leads to diminishing returns and performance decline, so it should not be used more than 10% in the overall yearly training load (including the race efforts in that 10%). Aerobically deficient athletes should focus more on Zone 2 training, because they will get the most benefit there than doing Zone 3 training.

When aerobically efficient athletes use small amounts of Zone 3 training, this can help elevate and peak their performance ready for race efforts. Somewhere in Zone 3 is typically the goal race pace heartrate for races (other than really long ultramarathons) as it sits just beneath the lactate threshold. This will allow you to sustain maximum pace and intensity for long periods of time without lactate accumulation.

You know when you are in Zone 3 as your breathing is laboured and you may not be able to sustain the effort for longer than a couple of hours or less.  Elite athletes will be able to hold this pace for longer.

Zone 4: Aerobic Vo2Max and Anaerobic Capacities

Zone 4 the pace slightly above the LT when you are going all out on a short interval ranging from 5 to ~30 minutes. The duration you can sustain depends a lot on your overall athletic capacity. You know you are in this zone as your legs will be aching and your heart pounding. This zone also has a powerful training effect, as any time spent training about the LT forces greater development of both aerobic and anaerobic metabolic systems. Both high intensity and endurance training increases the body’s ability to transport lactate away from fast twitch fibers.2

These adaptations occur fast, so when used once a week during utilization training cycles, you should notice fitness increases each week. The downside is you need more recovery following these workouts due to the imposed stress they cause on the body.

Most zone 4 training is done in short interval format with a 2:1, 3:1 or (sometimes) a 4:1 work to rest ratio. Therefore, a 6-minute interval should have about 2-3 minutes recovery between each effort. Typically, the shorter recovery time, the better, to encourage greater LT development. Most novice athletes will not be able to sustain intensities above the LT for more than a few minutes. Elite athletes can hold the pace for longer. Typically zone 4 intervals are a max effort intensity tailored to the specific interval length. Therefore, a zone 4 interval of 2 minutes will be at a pace the athlete can only sustain for two minutes, while a Zone 4 interval of 10 minutes, will be at a pace slightly slower, but still maxes out after 10 minutes.

Zone 5: Anaerobic Power / Muscular Strength Endurance 

This is your max effort sprint interval pace, a pace you could only sustain for between 5 and 120 seconds. This is a completely anaerobic effort using fast-twitch muscle fibers and muscle glycogen for fuel, featuring rapid lactate accumulation.  There are greater injury risks with small application of Zone 5 training, but it can be used through a capacity training cycle due to its important muscular strength developing aspects.

Zone 5 training should always be done in interval format with long rest periods between each interval to allow the ATP stores in the muscles to replenish prior to the next interval.

Next Article -> Part Ten - How to Choose Which Zones to Train in Regularly