Dr. Andrew Huberman, a Stanford neuroscientist, frequently emphasizes Zone 2 cardio as foundational to metabolic fitness. This aerobic exercise benefits the heart and lungs while profoundly impacting cellular health. Understanding how to identify this zone and the recommended weekly duration is key for optimizing a fitness routine.
Identifying Zone 2
Zone 2 cardio is an exercise intensity where the body primarily uses fat for fuel, occurring just below the aerobic threshold. While precise identification requires measuring blood lactate, most people can use a simple heart rate calculation. This zone corresponds to 60% to 70% of an individual’s estimated maximum heart rate. Maximum heart rate is roughly determined by subtracting age from 220, then calculating 60% to 70% of that result.
The “Talk Test” is a practical method for gauging this intensity. During Zone 2 exercise, you should be able to speak in complete, albeit slightly broken, sentences. You would be too breathless to sing or carry on a long discussion. On the Rate of Perceived Exertion (RPE) scale (where 1 is sitting and 10 is maximum effort), Zone 2 generally falls between 4 and 6. This mild-to-moderate effort confirms you are gaining metabolic benefits without overly taxing your system.
The Huberman Protocol Weekly Requirements
The recommendation for Zone 2 cardio is to accumulate a minimum of 150 minutes per week. For optimal health and conditioning, this target is often pushed toward 200 minutes per week. This duration is considered the minimum effective dose to drive physiological adaptations for cardiovascular and metabolic health.
This total time does not need to be completed in one session but can be broken up into multiple periods throughout the week. For example, a person could aim for three to five sessions lasting between 30 and 60 minutes each. Consistency is emphasized, meaning the regularity of reaching the Zone 2 state is more important than sporadic, high-volume efforts. Activities like brisk walking, cycling, or using an elliptical machine can achieve this weekly total, provided the intensity is maintained within the target RPE or heart rate range.
Core Mechanism Mitochondrial Health
Zone 2 training is highly recommended due to its unique ability to improve cellular health, particularly within muscle tissue. This exercise intensity directly stimulates mitochondrial biogenesis, the process of creating new mitochondria. Increasing the number and efficiency of these “powerhouses of the cell” is foundational to metabolic fitness.
Improved mitochondria become more efficient at utilizing fat as a primary fuel source during exercise. This process, known as fat oxidation, helps preserve glycogen stores and improves metabolic flexibility. Improved mitochondrial function also enhances insulin sensitivity, making cells more responsive to insulin and regulating blood sugar levels. Consistent Zone 2 work is a direct investment in long-term metabolic health and resilience against type 2 diabetes and cardiovascular disease.
Integrating Zone 2 with Other Exercise
Fitting the required 150 to 200 minutes of Zone 2 cardio into a weekly routine requires strategic planning, especially when incorporating other forms of exercise. Zone 2 should serve as the base of a comprehensive fitness program that also includes resistance training and higher-intensity work like Zone 5 or High-Intensity Interval Training (HIIT). Because of its lower intensity, Zone 2 training typically does not interfere with recovery from strength training sessions.
It is beneficial to separate Zone 2 sessions from strength training, or perform them at different times on the same day. For instance, one could perform a strength workout in the morning and a Zone 2 bike ride in the evening. Alternatively, Zone 2 can be performed on “active recovery” days to promote blood flow and enhance recuperation. This moderate-intensity work supports the body’s ability to handle the stress of Zone 5 training, creating a balanced stimulus for superior cardiovascular adaptation.