Zone 2: Understanding It the Way Your Body Does

There is a lot of flutter around Zone 2 training—it's become the buzzword on every social media reel and a part of almost every gym conversation.

So, I thought I would interpret it the way my body perceived and understood Zone 2, rather than get into the technical jargon that is already floating around.

My exercise journey restarted after 13 long years. (Yes, marital responsibilities and two kids did take that long!) Thanks to the Coastal Road Promenade that came up right across my home, I finally had the perfect excuse to start exercising again.

Initially, I started with just a walk—30–40 minutes. I barely walked about 1.5–2 km. I didn't invest in a smartwatch then. I wasn't even sure whether I would stick to the walking routine, let alone think of running.

But as I did this regularly, I started enjoying it- Consistency Compounds. Listening to podcasts, walking in front of the vast sea in the open—it became a small gift that I gave myself every time I went.

Trust me, at 40, with two boys, work and a home to run, this is indeed a precious gift.

On my birthday, my husband gifted me a smartwatch—and that's when I started tracking my progress.

Looking back at the exact numbers, I was walking at a pace of 10.6 min/km, with an average HR of 106 bpm.

Was that Zone 2?

I was surely not out of breath. I was mildly exerted. And I could easily sing my favorite song—which, by the way, is currently Galway Girl by Ed Sheeran.

This was 7 February 2026.

Fast forward six months of consistent walking and running.

I did a 10 km run at an average pace of 8: 30 min/km, with an average HR of 155 bpm.

This was somewhat hard to hard.

I could say the words of the song (still Galway Girl), but I definitely couldn't sing it!

And that's when I finally understood Zone 2.

Zone 2 is an exercise intensity where your heart and lungs are working, but not too hard. You can still have a conversation while exercising, but singing becomes difficult. Your body is using both fat and carbohydrates to produce energy, with aerobic metabolism playing the major role. It is an intensity that you can sustain for a relatively long time and that helps build your aerobic fitness and makes your body more efficient at producing energy.

Of course, there is much more science to Zone 2 than this.

And importantly, Zone 2 is not one fixed heart rate for everyone.

A smartwatch gives you an estimate of your heart-rate zone. The most accurate way to identify your individual physiological thresholds is to measure how your body responds during a graded exercise test—for example, using respiratory gas analysis or blood lactate measurements.

But for practical purposes—and to be on the same page as Instagram! —I'll share my estimated 5 heart-rate zones.

Zone	% HRR	My estimated HR
🟢 Zone 1	50–60%	124–135 bpm
🟢 Zone 2	60–70%	135–146 bpm
🟡 Zone 3	70–80%	146–157 bpm
🟠 Zone 4	80–90%	157–168 bpm
🔴 Zone 5	90–100%	168–179 bpm

 These are calculated using the Karvonen (Heart Rate Reserve) formula, based on my age and resting heart rate. They are estimates—not clinically measured physiological thresholds.

P.S.- The estimated HR and Zone 2 as my body perceives vary!

How do you calculate this for yourself?

Simply put the following prompt into any of the AI apps that you use and find your estimated zones:

I'm ___ years old and my resting HR is ___ bpm. Calculate my Zone 1, 2, 3, 4 and 5 heart rates using the Karvonen (Heart Rate Reserve) formula.

Please show me the calculation and present the results in a simple table. Clearly state that these are estimated heart-rate zones and not clinically measured physiological thresholds.

And there you have it.

You don't need to start by running fast.

You don't even need to run.

Start where your body is. Be consistent. And let your fitness catch up.

For educational purposes only. These are estimated zones and should not replace clinically determined exercise-intensity thresholds, particularly for people with cardiovascular conditions.