Cardio: Zone 2 and VO2 Max Training

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Summary

Zone 2 training: This is a type of exercise that is done at a low to moderate intensity (videos linked below show what this looks like), typically around 60-75% of your maximum heart rate. It is often referred to as the "aerobic zone" and is ideal for building endurance and increasing your aerobic efficiency and capacity. It is also one of the best tools for promoting health span, and preventing metabolic disease, which greatly increases your risk of developing heart disease, cancer, diabetes, Alzheimer’s, and other chronic illnesses.
Aerobic base: This refers to your body's ability to efficiently use oxygen to produce energy during exercise. Having a strong aerobic base means that you are able to exercise for longer periods of time without getting tired or out of breath.
VO2 max training: This is a type of exercise that focuses on increasing your body's maximum oxygen uptake capacity, also known as your VO2 max. This type of training is done at a high intensity and involves short intervals (4 minutes is recommended) of intense exercise followed by periods (also 4 minutes) of rest or low-intensity exercise. This can lead to improved overall fitness, increased energy levels, and reduced risk of chronic diseases such as heart disease and type 2 diabetes. In addition, research suggests that a higher VO2 max is associated with increased longevity, as it may help delay the onset of age-related diseases and improve overall health and vitality.

In simpler terms, zone 2 training is a type of exercise that helps build your endurance and aerobic capacity by working at a moderate intensity for longer periods of time. Your aerobic base is the foundation of your endurance and overall fitness, and having a strong aerobic base allows you to exercise for longer periods of time without feeling fatigued. VO2 max training is a type of exercise that focuses on increasing your body's ability to take in and use oxygen during intense exercise.

Simple Takeaways for Getting in Shape

For beginners, start with 30 minutes of Zone 2 exercise. After a couple of months, or when it feels comfortable, bump that up to 45 minutes 3 times weekly.
For beginners, after about 6 months of Zone 2 training, start incorporating 4 Minute Interval Training. This is described below.
Many elite endurance athletes (such as Tour de France bikers) will only do Zone 2 and VO2 Max training. They’ll spend 80% of their time in Zone 2 (about 30-35 hours weekly) and the remaining 20% doing 4 minute interval training. So this regimen works!

Why You Should Care about Zone 2 Exercise - Building Aerobic Efficiency

Aerobic fitness pertains to how efficiently your body can deliver oxygen to the muscles, and how efficiently your muscles can extract that oxygen. This is related to obvious activities like long distance running or cycling, but improved conditioning can also provide more energy for daily activities like working or buying groceries. Any movement shorter than brief, high intensity exercise uses oxygen to generate ATP. This is called aerobic exercise, and Zone 2 increases aerobic energy efficiency. Zone 2 exercise is long, low-moderate intensity, steady-state bouts of endurance work that increase the number, size, and energy (ATP) production of the mitochondria in your cells (admittedly I am unsure if it’s just within the working cells or not). In this podcast with Peter Attia, “Iñigo explains that zone 2 is basically the highest level of exertion that is effectively pure mitochondrial oxidative phosphorylation before you start to net accumulate lactate.” In other words, it is when lactate production and lactate clearance are the same rate. Additionally, "Zone 2 is defined as your highest metabolic output/work that you can sustain while keeping your lactate level below two millimole per liter.” By definition, Zone 2 exercise should not generate a strong ‘burn’ within your body.