Ray's take:

We know Zone 2 is great for our metabolic and cardiovascular health.

However, Zone 2 is just distracting enough that is hard to do work (like work, work) at the same time.

I find zone 2 is also way easier running or playing tennis (vs biking). It's not easy for me to get my heart rate up to 125 on peloton bike without smoking my legs.

So I had a thought - Is Zone 1 enough?

Who I am:

I'm Ray, a doctor that is obsessed with helping you found your own health program, to reach your health objectives.

Zone 1 vs Zone 2:

Review:

Cardiovascular exercise is any activity that increases your heart rate and blood circulation throughout your body. It improves the efficiency of your cardiovascular system in absorbing and transporting oxygen, which prevents disease.

It is typically accepted that you start working cardio at 50% of your maximum heart rate, which is Zone 1.

Maximum heart rate is estimated at 220 - your age.

For example, I'm 39, so my max heart rate is 220-39 = 181. My zone 1 and zone 2 heart rates:

You should know yours.

Now let's take a look at the benefits of each:

Source: Exercise and cardiovascular health: A state-of-the-art review

My conclusion

Both Zone 1 and Zone 2 training have health benefits, and fit my life and health program.

Zone 1

I like Zone 1 because it allows me to do work while exercising. Getting heart rate to 90 is quite easy while using my Peloton bike on "just ride."

I have a "spin tray" which is like a desk that fits on the Peloton handles, so I can do calls, review video, do research, and even write articles (like this one, right now!) . Zone 1 still provides metabolic benefits....so why not?

I also like Zone 1 if i'm sore, such as days after squats or deadlift (which I also am, right now).

Zone 2

Zone 2 training has a higher impact on aerobic capacity, fat oxidation, and cardiovascular improvements. However, it does demand a level of effort that makes doing work more challenging.

It's still a fantastic option for multitasking in a different sense—like listening to a podcast or audiobook—which can still make the time fly by (or reduce pain). This is great when you need a break or want to learn something new.

My favorite Zone 2 exercise is playing tennis - this is pure fun, no pain. I love it.

TLDR: Do both Zone 1 and Zone 2, in a way that fits your life

Sources:

San-Millán I, Brooks GA. Assessment of Metabolic Flexibility by Means of Measuring Blood Lactate, Fat, and Carbohydrate Oxidation Responses to Exercise in Professional Endurance Athletes and Less-Fit Individuals. Sports Med. 2018 Feb;48(2):467-479. doi: 10.1007/s40279-017-0751-x. PMID: 28623613..

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

Pics

Me smiling doing Zone 1 while writing this article.

Yes I'm actually writing this article, right now.

This was the workout I did while writing this article.