TLDR: What you need to know

• Zone 2 workouts are when your heart rate is 60% of max, for a prolonged period of time. You can think of this as "cardio" from fast walking, jogging, biking, swimming, etc. This is a foundation of any health program because it is relatively easy, and so good for your health. We highly recommend it for everyone on the Ray Wu MD program.
• Zone 2 has so many health benefits, with the most important being that it is the foundation for good metabolic health.
• Zone 2 helps metabolic health by optimizing your mitochondria, the energy producers in your cells.
• When you optimize your mitochondria, your body gets better at using fat for energy.
• Literally everyone in all age categories should do zone 2 workouts. It's never too late to start.

Ray's Take

For most of my life, I was never the biggest fan of "cardio" which i used to think of as running.

I hated running. When I was in medical school, the only reason i would run is to burn calories so I could eat or drink more than usual.

Today, I realize how dumb I was back then.

Cardio, which we'll start calling "zone 2," we'll define as a exercising to the point where you can talk to someone else. However, it would be annoying for you and your conversation partner as you would breathing hard and speaking strangely.

In this state, your heart rate would be 60-70% of your max, which is largely determined by your age (roughly 220 - age).

Why was I wrong?

First, the reason to do zone 2 is not to burn calories. Rather, when doing zone 2, you are training your mitochondria (your cell's energy producers) to use fat for energy. This is is so important for metabolic health. One of the saddest things is that most people with a lot of body fat cannot use it for energy because their mitochondria are unhealthy. People who train zone 2 do not suffer from this problem.

Second, you are promoting something called "non-insulin mediated glucose uptake." Suffice it to say that this makes your body more insulin sensitive, which is the opposite of diabetes, and exactly what you want.

Third, doing zone 2, can increase heart rate variability (HRV), which is a good thing. When your body is adaptive, less stressed from having more parasympathetic response (rest and digest) vs sympathetic response (fight or flight), you have increased HRV. This is a good thing.

Fourth, and maybe most obviously, zone 2 is the easiest, lowest stress way to exercise, and exercise in general improves cardiovascular health.

Last, doing zone 2 isn't really that hard, and its therapeutic benefits are immediate. When I'm doing zone 2, I'm sweating, I'm feeling productive, I can even do work on my phone, listen to a podcast, or watch a game. So why not?

I'm literally optimizing my mitochondria and boosting my metabolism while being able to do what I was going to do anyways.

It's a no brainer for me, and should be for you too!

How can you do zone 2?
Literally any way you want:
- run outside
- run on a treadmill
- bike outside
- bike inside (I use a peloton bike on "just ride")
- swim
- row
- walk briskly

The only thing you should do is monitor your heart rate so you can see your improvement. The more you do, the higher your heart rate can be while still feeling good and "being able to talk to someone."

I do this through an apple watch but there are many other options.

How much zone 2 should you do?
There is no max. We recommend at least 2 hours a week for everyone on the Ray Wu MD program.

I personally use a Peloton bike for 2-3 hours per wk while maintaining 155-120 beats per minute.

My saving grace / unfair advantage? I love tennis, and have played my entire life. I play roughly 4x a week, and maintain an hour of 125 bpm. This gives me a "free and fun" 4 extra hours of zone 2 per week.

How much zone 2 should you do?

Literally as much as you have time for.

It's almost impossible to do too much.

Does zone 2 make me look better?

Honestly, yes. It will.

How? Zone 2 does burn calories and burning calories will help you lose weight and fat.

However, doing zone 2 is NOT for the calorie burn. It is for improving your cardiometabolic health.

Please do not reward yourself with pizza, ice cream, or a burger because you did zone 2.

It is way easier to not work out, not eat those bad foods, and have the same calorie equation.

Zone 2 will also not improve your strength or increase muscle much. For that, you need to work on building strength.

How do I start?

Easy - just start.

Run, jog, walk, bike, swim.

Go as fast as you can while being able to talk.

Go as long as you feel like (minimum 20 min).

Note - if you make it to 30-40 min, you'll feel better and things will get easier. This is known as the "runners high."

Cool knowledge for normal people

Mitochondria

Mitochondria are in all human cells. They are responsible for producing Adenosine triphosphate (ATP), the main energy source of the cell.

How mitochondria turn fat into energy

Mitochondria take fatty acids, and turn them into energy through a process called beta-oxidation.

When you do zone 2, you are working at the hardest level you can, while getting all of the energy to do so from fat. This causes your mitochondria to get better at "burning fat."

Optional info for nerding out

Beta oxidation from Wikipedia

Podcast from Peter Attia: Iñigo San Millán, Ph.D.: Zone 2 Training and Metabolic Health