We receive lots of questions about heart rate monitors.    Common questions include:

  • Should I use a HR Monitor?

  • If I have one, how can I maximize its value in my training?

  • What about MetCons?  

In this article, we answer those questions and provide some additional information about how to use a HR monitor to support your capacity gains. Let’s take a look at these questions in some detail.

Should I use a HR monitor? You DO NOT need it to develop monster capacity.   The four-minute mile, sub-2:10 marathon, and sub-1:45 800m - along with countless other feats of athletic greatness - predate the HR monitor.    We consider them nice to have, if used correctly.  If you don’t have one, don’t worry!

I already have one.  How can I use it to maximize my gains? Before we get into the details, there are two programming rules that supersede all others:

1)   Athlete goals define program design.  Information gathering from equipment like a HR monitor is an aspect of program design. If your training program does not consider collection of useful information, it’s incomplete.

2)   The data on the HR monitor is secondary to performance outcomes.   If your performance improves, your program is working!  Use HR data for analysis but use performance for measurement.

OK, got it.  Now how do I use this thing?

Our capacity framework utilizes five training day structures.   Each of the days has a specific training intent, which produces adaptations beneficial to the functional fitness athlete. Data collection and interpretation for each of the days will vary. If you’re not working with us, no worries.  Your conditioning program likely has many of the same elements.  This chart presents the training days, along with the intent and desired adaptations of each:


Quick nerd-note:  Glycolytic flux is the rate at which molecules pass through the glycolytic pathway.  The familiar characterization of three energy systems, which differentiates the systems by duration of energy supply, is an extreme oversimplification.   In practice, the three well known energy systems are sub-processes whose interactions are governed by numerous factors beyond the scope of this article.  Click here for an introduction to some more advanced concepts in bioenergetics.

Because each of the training days has its own structure, intent and desired adaptations, the HR data to be captured will vary slightly among days.   

Endurance Days: We advise people to work at 70-75% max HR on endurance days.   This may initially feel slow, but it’s not slow to your heart, or your mitochondria!   This intensity level reduces the amount of glycolytic energy and requires the oxidative system to do all of the work.  With time, your work rate will increase even at the same HR.    

Interval Days: Recall that the key parameters for interval training are (1) maximum average power and (2) minimum range between intervals.  For example, on 500m rowing intervals, 1:45 – 1:45 – 1:45 – 1:45 – 1:45 is a better result than 1:35 – 1:40 – 1:45 – 1:50 – 1:55, even though they both average 1:45 / 500.   Peak power is not important in interval training; attainment of peak power exhausts numerous muscle fibers such that they cannot be recruited for subsequent intervals and therefore are not trained properly.   Repeatable power is what counts.   HR will always be very high during intervals. It’s the HR recovery and HR at rest that provides useful information.  

Threshold / speed days / time trials:   Speed days require your max sustained work rate. Therefore, your HR will climb very high and stay there; typically, athletes record from 87-92% during most of a speed day. 

Polarized Days: A Polarized day is an endurance day with very intense bursts, to activate additional motor units.   Use the HR monitor to discover and sustain your endurance pace.    During the bursts, your HR will skyrocket.   The magic of Polarization occurs after the bursts, when you recover at endurance pace.    Do not allow yourself to drop below your endurance work rateto allow your HR to come down quicker.  Instead, return immediately to endurance pace and track how long it takes for your HR to come down after each burst. 

Flux days: A flux day combines endurance work with varying duration high intensity intervals.   (They can also be thought of as zero-rest intervals).  As with Polarized Days, use the HR monitor to discover your endurance pace.   However, unlike interval or polarized days, we prefer to track HR during the higher intensity flux sessions.   The prescribed intensity of a flux session varies, so if you can track the HR progression during the flux session, you can gain some more granular insight into your aerobic conditioning.   

The key data points from each of the days, and how to interpret them, are here:


What about MetCons?

A MetCon most closely resembles a flux day in that intensity can change within the workout.   A MetCon pairing toes to bar (moderate intensity) with snatches (very high intensity) illustrates this very well.   However, unlike a FLUX day, there is no scheduled return to endurance pacing.  The intensity of a MetCon is always near the highest you can do at that point.   

This intensity is the reason for MetCons’ limitation as a broad conditioning tool.  From an energy standpoint, MetCons require you to work at the highest sustainable rate of glycolytic flux possible.   This is why our capacity framework is focused on raising your aerobic power and your ability to remove glycolytic waste products – the result of these two is greater sustainable power output.

Because of this energy demand, HR during MetCons should always be quite high and the monitor will confirm this.  We generally advise athletes to leave the monitor in the bag for MetCons and rely only on their times to evaluate performance.   The high variability of MetCons renders data analysis very difficult. Does your HR spike on pullups, or was that because they were paired with thrusters?  

Some athletes tell us that they’ve used their HR to identify when to take short breaks during a MetCon.  For example, they report better results doing 21 burpees in a WOD as 7-7-7 with short pauses rather than 21 straight through.   We remind these athletes that the goal of conditioning is not to optimize breaks, but to create an engine which doesn’t need them. 

For more information about our Capacity Framework, go here.   For feedback on this article or general comments, send an email