We want heart rate training to be a staple in your program no matter what your goals are.  

We also want it to be fun and engaging.  

Last, but certainly not least, we want your zones to be accurate for your unique fitness and physiology.  

We know that most people are not going pay someone to do invasive lab-based testing to measure heart rate zones and we know that many people don't have access to this type of service anyway.  

Anaerobic Threshold (AnT)

Anaerobic threshold is a metabolic threshold characterized as the highest workload at which the body is able to achieve a steady-state condition, so that the lactate accumulation and removal are in balance.  Therefore, anaerobic threshold is important to long-term performance ability as it represents the highest performance intensity that can be tolerated for relatively long periods. 

There are several accepted ways to measure Anaerobic Threshold – from metabolic lab tests, lactate tests, talk tests, beep tests, distance and time tests, etc.  Elite endurance athletes might have reason to dial in this AnT range more than the most people by completing lab-based testing.

Max Heart Rate (MHR)

The oldest and most widely used formula to estimate MHR is to subtract your age from 220.

For example, if you're 45 years old, subtract 45 from 220 to get a MHR of 175. 

Then heart rate zones are set by using percentage ranges of the MHR number.

It's important to note that maximum heart rate is only a guide.  You may have a higher or lower maximum heart rate, sometimes by as much as 15 to 20 beats per minute. 

There may also be slightly different calculations that take into account sex differences in target heart rate zones.  These differences are so small that most casual athletes don't need separate calculations for men and women.

Bottom Line

For most people, getting a good estimate of AnT range and Max HR combined with the power of Morpheus’s 3 dynamic heart rate zones provides enough accuracy to both use the data effectively and get amazing results.

Morpheus Heart Rate Zones

In the General Settings of the app, there are 3 things to be aware of that affect your default heart rate zones (ie your zones when you are at 100% recovery score).

  1. Max Heart Rate – if you don’t edit this, it will calculate this number based on your age.
  2. Rate your overall fitness level – you can choose High, Moderate, or Low.  This is very subjective and it’s not a rating of you against anyone else; it is just how you interpret your own fitness level.  
  3. Anaerobic Threshold – the app asks if you know this number.  If you don’t you can choose “No”.  But the remainder of this article shares how you can easily estimate it by using the Morpheus app with the M3 and/or the M5.  

The items above may provide enough accuracy for you, especially since Morpheus zones are dynamic (they change every day based on recovery score) and not static like all other heart rate zone calculation methods.  So you may not ever need to do a test like the one outlined below.  But you can!  And that's the point of this article.

AnT and MHR Estimation Test

Below outlines an easy, non-invasive way to use Morpheus to estimate your personal AnT and Max HR.  

This is certainly not the only way to complete an estimated AnT and MHR test. But we've had a lot of success with this for the average person that does not have a lot of experience with heart rate training.  And when comparing to actual lab-based tests of the same people, this test is almost always within just a couple of beats per minute of lab measured AnT and MHR.

NOTE: You want to be sure that you do this test on a day when you are between 90% - 100% recovered per the Morpheus recovery score.

Test Equipment Requirements:

  • Morpheus App
  • M5 and/or M3
  • Cardio equipment (treadmill, bike, elliptical, rower, stepmill, etc)

NOTE:  If you do not have access to cardio equipment, you can do this test outside or inside with no equipment.  You just need a way to gradually increase your intensity to get into the Morpheus red zone.

Step 1:  Warmup:

You don't want to do a test like this "straight out of the box"; you should complete a warmup first.  There's no standard on how you need to complete this warmup.   Just gradually increase your heart rate over 10-20 minutes until you feel good, not tired.  Maybe even include some harder efforts within the warmup (such as some 20-30 second "bursts") to prep the body for a hard effort.

Step 2:  Test:  

You want to gradually increase your intensity so that your heart rate goes up.  You want to get just into the bottom of your RED zone and then hold it there for as long as you can (no need to go longer than 10 minutes).  How long you can sustain this depends on your cardiovascular fitness level and training history.

Make a mental of how this intensity feels on a scale from 1-10.  There are two examples of scales shown below for your reference.

Estimated AnT should feel like a 7-8 out of 10.  It should be difficult but sustainable.

Step 3:  Enter and Calculate:

If sustaining intensity at the bottom of your RED zone feels like a 7-8 out of 10, then you can be quite confident that you've accurately estimated your AnT.

  • If the bottom of your RED zone feels like a 9 or 10, then you need to enter a number lower than that for your AnT.

  • If the bottom of your RED zone feels like a 4, 5, or 6 then you need to enter a number higher than that for your AnT.

Enter the Heart Rate number that most accurately represented your AnT zone into the Anaerobic Threshold section in General Settings of the Morpheus app.

Multiply your AnT number by 1.12 to get your Max Heart Rate number.  Enter that number into the Max HR section.  Round up or down as needed.


Estimated AnT = 164

Estimated MHR = 164 x 1.12 = 183

Press SAVE on the bottom of the screen.

This will set your baseline 3 heart rate zones in the Morpheus app.  And remember, these zones will change every day based on your recovery score for that day.

IMPORTANT NOTE:  As your fitness increases (or decreases, but hopefully not), your AnT and MHR may change.  If you notice that it's becoming more difficult to reach your RED zone on days when you are 90-100% recovered, we'd recommend repeating this test to see if a recalibration of your numbers is needed.

Now you're ready to embark on the exciting journey of heart rate training with Morpheus.  Thank you for joining us!