Heart Rate Training (HRT) – Part 1

Heart Rate Training is the idea of training to a particular heart rate range. I am interested in looking at this sort of training and the advantages of the training but first let’s take a look at a typical CrossFit from this morning’s workout. The warmup was about 10 minutes at a low heart rate (less than 80 bpm). The workout itself was five (5) RFT (Rounds for time) consisting of:

I finished in around 28 minutes.

Here is my heart rate throughout the workout.

My heart rate (HR) climbed as I progressed through the workout from my starting rate of around 70 to a peak HR of 169 bpm. Using the standard heart rate calculation my max heart rate is 220 minus my age or 220-58 = 162. So I exceeded my maximum heart rate for some period of time.

The app graded the exercise as 11 minutes of maximum. I think the app uses the standard 220 method so it’s grading 85% of the 162 (from above) or 138 bpm as the start of the maximum effort range.

I did the workout today in a fed start after eating 4 strips of bacon, 4 eggs and 20 oz of coffee with salt water about an hour before the workout. I used to always do morning workouts fasted but I am trying to expand my protein muscle synthesis window.

RER and Exercise

So what is the problem with working out at a heart rate exceeding your maximum? Obviously I lived and didn’t die so there’s no damage that I can see/feel. I am recovering well from the exercise, too.

I think the problem is particular to fat adapted athletes. The problem is that fat is my fuel and not carbohydrates. That does not lend itself to higher intensity workouts nearly as well as lower intensity workouts. This can be seen looking at the RER chart I made from my own VO2max testing.

This chart shows the range of fat burning as noted from the RER value of 0.7 or less (RER is /100 of the scale). When the RER number goes above 0.7 that means that some glucose or glycogen is being spent. When the number hits 1.0 that means that no fat is being oxidized (at least as I understand it). This also correlates to the heart rate. The red line marked Max HR is the 163 bpm number (I was 57 at the time I did that test).

The right hand orange vertical is the point where the RER reaches the point where all of the energy is still coming from fat (RER=0.7) and in this instance correlates to a HR of 120 bpm. That indicates, at least in a rough way that I want to be at or around 120 bpm MAXIMUM to fully utilize the main fuel source I have which is fat.

Yes, I can go higher than 120 bpm, but not for long. In this workout I went higher for around 11 minutes. My watch indicates the range by the color of the heart symbol on the watch as well as the number itself (which the user can keep in mind their range). The watch can also be set to continuously monitor heart rate as follows:

In the next installment I will take a look at the methods to train to heart rate.