What is Zone 2 training?

By Coach Hunter Bennett

Zone 2 training has become a buzzword among endurance athletes, fitness enthusiasts, and casual exercisers across the globe.

But what is Zone 2 training, and is it all it’s cracked up to be?

What is Zone 2 Training: The 5-Zone Heart Rate Model

Zone 2 refers to the second zone in the 5-zone heart rate model.

As its name implies, the 5-zone heart rate model divides your exercise intensity into five zones based on a percentage of your maximum heart rate (MHR):

• Zone 1 (Very Light): Aligns with 54–73% of your MHR, easy work that is often used for warm-ups, cool-downs, or active recovery.
• Zone 2 (Light): Aligns with 74–83% of your MHR, moderate effort exercise where you can maintain a conversation comfortably.
• Zone 3 (Moderate): Aligns with 84–88% of your MHR, comfortable but more challenging. This is often used for tempo and threshold work.
• Zone 4 (Hard): Aligns with 89–93% of MHR, where breathing becomes heavy. This is suitable for longer intervals.
• Zone 5 (Maximum Effort): Aligns with 94–100% of your MHR, typically unsustainable for long durations. Suitable for shorter intervals.

What are the Benefits of Zone 2 Training

Zone 2 training offers benefits for anyone looking to improve their aerobic fitness and endurance performance:

1. Enhances Aerobic Capacity: Zone 2 training strengthens your heart, increasing stroke volume (the amount of blood your heart pumps per beat) and promotes better oxygen delivery to your working muscles.
2. Improves Fat Utilization: Zone 2 training improves your ability to break down and use fat for energy, which can help you sustain long distance performance.
3. Develops Mitochondrial Density and Function: Zone 2 training stimulates the growth and efficiency of your mitochondria (known as the “energy powerhouses” of your cells). This improves your muscles’ ability to create energy.
4. It is Easy Recover From: Arguably the biggest benefit of Zone 2 training is that it is easy to recover from. This means you can do a lot of it without impacting your other training negatively. This is one of the reasons you see elite endurance athletes doing such high volumes of Zone 2 training – because they can do heaps of it without running into recovery issues.

Cons of Zone 2 Training

Although some people describe Zone 2 training as the “best” way to build endurance, it does have some downsides.

1. Time-Consuming: As exercise intensity increases, it becomes more effective per unit of time. While Zone 2 training is easy to recovery from, it requires larger volumes (and often longer sessions) to have benefits. If you have limited time to train, focusing solely on Zone 2 may not provide the intensity needed to maximize your performance in the time you have available.
2. Unlikely to Maximize Improvements in Lactate Threshold: Lactate threshold is the exercise intensity at which lactate starts to accumulate in the blood faster than it can be cleared, and it is a key determinant of endurance performance. Zone 2 training can indirectly increase lactate threshold by improving your ability to produce energy aerobically, but it does less to enhance your body’s ability to buffer lactate when exercising at higher intensities. In this manner it less effective than Zone 3, 4, and 5 training.
3. Monotonous for Some: The steady and moderate pace of Zone 2 training can feel repetitive or dull, especially for those who love high-intensity efforts.
4. Harder Adherence: This may sound counterintuitive because Zone 2 is technically “easier,” but people who have not done much aerobic training or have higher body weights can struggle to keep their heart rate low enough for Zone 2 training. These individuals might be better served worrying less about their heart rate and simply getting fitter by running at moderate paces until they can maintain a low heart rate.

Who Should Try Zone 2 Training?

Zone 2 training is important for anyone looking to maximise aerobic fitness and endurance performance, because it allows you to accumulate training volume with minimal fatigue.

However, it should be combined with higher intensity training to maximise improvements in performance.

Conversely, if you are solely exercising for health benefits, and/or extremely time poor, you will get more bang for your buck doing something like high intensity interval training.

This will give you more health and performance benefits per minute than Zone 2 training.

How Much Zone 2 Training Should I Do?

The amount of Zone 2 training you do should be dictated by your total training volume.

You will commonly hear people say that 80% of your training should be Zone 2, while the remaining 20% should be of a higher intensity. However, this recommendation comes from observing how elite endurance athletes train, which won’t apply to most people.

See, elite athletes often accrue more than 20 hours of aerobic training per week. As a result, for them to recover from such large amounts of training, most of it needs to be in Zone 2, otherwise they run the risk of over training and injury.

But if you are only training 3-4 hours per week, these recommendations don’t apply because you don’t have much to recover from.

Instead, it is better to base your Zone 2 needs on how many sessions you are doing per week.

• 1-2 Sessions Per Week: If you are doing 1-2 sessions per week, then most of them should be of a higher intensity, because this will maximise your training outcomes. You can integrate some Zone 2 work into your warmups and cool downs.
• 3-4 Sessions Per Week: This is where you might have one session dedicated to Zone 2 training. The remaining sessions should be comprised of tempo work or interval training, with Zone 2 warmups and cool downs.
• 5+ Sessions Per Week: This is where you would expect to see your Zone 2 volume start to increase. You could have 2-3 higher intensity sessions (i.e., threshold work, short and long intervals), with the rest of your training consisting of Zone 2 training to ensure you don’t exceed your recovery capacity.

What is Zone 2 Training: Take Home Message

Zone 2 training is a great way to improve aerobic fitness and improve health, while minimizing fatigue. However, it’s not the best choice for those with limited time.

And if you are keen to start strength training but are not sure where to start, check out some of our programs or feel free to contact us for more information.