What is “Zone 2” Exercise?

by Adam Brown  BScPT, MClScPT
updated Sept 16, 2024

What is “Zone 2” Exercise?

Zone 2 exercise is a type of workout completed at a specific intensity designed to cause an adaptation in the body’s metabolic processing of fuels. Exercise intensities are divided into zones based on physiological changes in how the body produces the required energy and are often defined by physiologic events. These zones can be estimated by heart rate, changes in breathing and gas exchange, as well as changes in blood lactate concentrations. Zone 2 exercise is characterized by a relatively low intensity, allowing it to be performed for longer durations. The body can recover from Zone 2 exercise more quickly than from higher-intensity workouts, enabling more total training to be incorporated into a week. This type of exercise can be done with any steady-state activity, such as walking, biking, or using a treadmill.

Why Do Zone 2 Exercise?

Engaging in Zone 2 exercise requires the body to utilize fat as a substrate at a relatively higher percentage of energy production compared to higher intensity exercises. This process enhances a person’s ability to use fat as an energy source even at higher intensities by increasing the number, size, and efficiency of mitochondria in working muscle cells. Improved mitochondrial density, size, and efficiency are hallmarks of good overall metabolic health, making Zone 2 exercise particularly beneficial for enhancing metabolic function and endurance.

How do I target Zone 2?

There are 3 different ways to target zone 2 exercise and ensure you are within the range for optimal results. The simplest and most accurate method that requires no equipment is the talk test. If you can hold a conversation with minimal discomfort while exercising, you are likely in Zone 2. Another method is monitoring heart rate zones, which can be very accurate but may vary across different exercise modalities like biking versus treadmill running. However, heart rate can be influenced by other factors such as caffeine, dehydration, and stress. The most precise method is measuring blood lactate levels, which involves using a lactate meter and finger-prick blood testing. Zone 2 is typically defined as the point where blood lactate increases by 1 mmol/dL above the individual’s resting value. This method is particularly useful for athletes to benchmark against their heart rate, pace, and power output, though it is less practical for everyday use.

To get started with Zone 2 exercise using a talk test, begin by increasing your speed slowly and in stages. You should be able to speak in sentences with only slight discomfort and you should be able to maintain nasal breathing, assuming you have no nasal congestion. Start with 15 minutes in Zone 2 and gradually increase the duration according to your physiotherapist’s plan. Make an effort to remain hydrated throughout your exercise. Record your session using a wearable device so you can share the results with your team for better monitoring and adjustments to your training plan.

About the author

Adam Brown

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