Know Your Zones - How To Get The Most From Your Endurance Training

Knowing your training zones tells you how hard to push yourself for each session, so you can be targeted with your training, recover better and reduce the chances of injury.

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It is important that you discover your own personal training zones as using a % of your maximum heart rate can be very inaccurate. The fitness of the individual can also vastly effect where these zones lie, making calculations more of a guesstimation. This is why metabolic testing or field tests are so important when defining your zones.

What are the key zones?

Zone 1 – Recovery Zone

Zone 1 is your recovery zone, which is used to help flush out waste products built up after a hard workout.

During hard intense sessions you produce hydrogen ions that impact muscle contraction and affect performance. A low intensity recovery session at zone 1 will help flood the body with oxygen to help remove these hydrogen ions.

What intensity/heart rate: 10-20% below your aerobic threshold heart rate, or below 56% of your VO2 max.

When to use: The day of, or after a hard session.

Zone 2 – Endurance Zone – Building your aerobic engine

Just above your recovery zone is your endurance zone, which is used to help build your aerobic base. This is the intensity where you build the foundations of endurance performance.

Training at this zone helps:

  • Increase your VO2 max

  • Increase the size and number of mitochondria (in slow twitch fibres), which is the powerhouse of the muscle cell and where energy is produced

  • Increase the number of capillaries surrounding the muscle, which will increase oxygen and glucose availability. This will also help get rid of lactate more quickly

  • Increase myoglobin so you can carry more oxygen to the muscles

  • Strengthen the heart, which increases stroke volume. This means more blood can get pumped around the body

  • Increased number of slow twitch muscle fibres (sustain space for long distances)

  • Improved utilisation of fat as energy

What intensity/heart rate: Up to aerobic threshold (AeT)/ventilatory threshold 1(VT1 - this is the point where you begin to produce lactate).

When to use - To build your aerobic base. Your easy slow, long distance sessions.

Know your zone - when you train at zone 2 you shouldn’t be adding in any high intensity efforts as this will increase lactic acid, which will blunt the desired adaptions.

Zone 3 and 4 - The Tempo and Threshold zones

This is the intensity when you begin to produce lactate (aerobic threshold) up until the maximum point where you are able to remove lactate (anaerobic threshold/FTP). Anything beyond your anaerobic threshold (AnT) will mean you are producing lactate more quickly than you can get rid of it. This means you will tire quickly.

We can split this zone into two parts. The Tempo zone and the Threshold zone.

Zone 3 - Tempo Zone

The lower part of your threshold zone is closer to your aerobic threshold. This part of the zone is referred to as 'No man's land' as you aren’t pushing yourself hard enough to see any performance gains, but you're also working too hard for it to be a recovery session or to see the full benefits of zone 2 work (producing lactate blunts aerobic glycolysis).

The lower threshold would be more applicable to longer distance events where your race pace would be closer to your aerobic threshold (AeT) than your anaerobic threshold (AnT).

Zone 4 - Threshold Zone

The upper end of your threshold is that of which is close to your AnT. At this point you become better at withstanding lactic acid and removing it, and you are able to increase your anaerobic threshold closer to your VO2 max. This means you can race harder for longer.

“Train with lactic acid so you get better at removing it”.

These are the sessions that are used to build upon your base. So after doing more endurance and base training to ‘build your engine’. You would do more threshold work to build up how much of your engine you can actually use.

What intensity/heart rate: AeT to AnT

Lactate vs lactic acid
Lactic acid is made up of lactate and hydrogen ions (H+). Lactate can be recycled and reused as energy where the hydrogen ions cause acidity, which is what affects performance and slows you down at high intensities.

Zone 5 - VO₂ Max Zone

Your VO2 max zone is the intensity from your AnT to your max heart rate . Similar to the endurance zone, this zones also increases your VO2 max.

This is done by:

  • Improvements in mitochondria

  • Increased capillarisation

  • Increased myoglobin

  • Strengthening of the heart

  • Increased oxygen kinetics (less energy used to get up to race pace - less oxygen debt)

These sessions are typically long intervals (2-4 mins) totalling 12-20mins with equivalent recovery times. Any longer than 4 minutes will mean you won't be able to hit the required intensity

Intensity/heart rate: Anaerobic threshold to your max heart rate.


When to use - These types of sessions are used well combined with endurance zone work during your base phase given the similar outcomes.

Zone 6 - Your Anaerobic Zone

Your anaerobic zone is the high intensity zone used to flood the body with lactic acid, recovering a little but not fully and repeating the process. This teaches the body to get better at tolerating and clearing lactic acid out of the system.

Similar to the threshold zone, training at these intensities will help you improve your anaerobic threshold and how much of your VO2 max you can actually use.

Intensity : > 100% VO2 Max. At these intensities, you're better using pace, power or perceived effort as a measure of intensity, rather than heart rate as it will be difficult to control.

When to use - This type of session works well interchangeably with your threshold sessions.