Heart rate monitor in CrossFit

Meyken Houppermans
Founder and Head Coach
How useful is wearing a heart rate monitor in  CrossFit?

 What does a heart rate monitor do?

A heart rate  monitor provides you with feedback on how fast your heart is beating. Heart  rate during exercise is often seen as an indicator of intensity and of cardiorespiratory  health. A number of aspects are important to take into account when talking  about using a heart rate monitor:

-         Resting heart rate

This is your  heart rate during rest. If your resting heart rate is low, it is plausible  that the amount of physical and mental strain on your body are in balance and  your cardiorespiratory system is in good shape. If your resting heart rate is  elevated for more than 10 percent a few days in a row, it is plausible your  body is overloaded and in need of rest. It might also be the case that your  resting heart rate is low or high by nature, of you are on medication that affects  your heart rate.

Furthermore, we  need to mention the parasympathetic overtraining syndrome. This is a severe type  of overtraining characterized by a heart rate that is very low during rest  and barely increases during exercise. The dangerous part of this syndrome is  that the symptoms can be misleading. Because your heart rate is low, you  might think you are in good shape when in fact you are severely overtrained. Consequently,  proper treatment often comes too late.

-         Maximum heart rate

Maximum heart  rate is often seen as an indicator of intensity and a reflection of cardiorespiratory  health. More experienced athletes are often able to reach a higher maximum  heart rate during training. But hereditary predisposition, illness and age  can affect your maximum heart rate, among several other factors.

-         Training recovery heart rate

This is the  number of strokes your heart rate drops after the exercise. In general, the  fitter you are, the faster you will flow back to the heart rate you had at  the start of the exercise, and the faster you will recover from it.

Measuring (relative) intensity

CrossFit is constantly  varied high intensity functional movements. Functional movements are  characterized by large loads (force) over long distances (distance) quickly  (time). The load and distance are the work you have to do, for example  lift an 80 kg loaded barbell (load) from ground to overhead (distance). The  intensity is determined by the time it takes you to lift.

In CrossFit  intensity equals power, and power = (load x distance) / time. Power is the  direct display of your work: 80 kg loaded barbell (load) for 10 reps from  ground to overhead (total distance) in 90 seconds (time).

Calculating intensity  (power) makes it possible to track and evaluate your progress based on  measurable, observable and repeatable data from your workouts. More load,  more reps, quicker.

In CrossFit we  explicitly emphasize the importance of relative intensity. Working out  at high intensity is key for results. This level of high intensity needs to  be appropriate relative to your physical, mental and emotional tolerances. The  idea is that we all  have our own  individual limits of capacity, yet if we all, despite our differences in  fitness level, work near our individual limits of capacity, we will all have  the same increased benefits from a workout. Therefore, it is not about your absolute  output of a workout, but about the relative output: your results today  compared to your results yesterday (CrossFit, nov 2019).

Why wear a heart rate monitor?

As mentioned  above: intensity (or power) can be measured, but heart rate is not part of the  math. Why is that?

A heart rate  monitor measures your body’s response to the work. Heart rate is a  direct response to variations in blood pressure, breathing rate and muscle  contractions resulting from your effort and technique during the exercise.

Although a  heart rate monitor is often used to measure intensity, it does actually not do  that job. Heart rate is not an instant reflection of your work. It takes some  time before your heart rate responses to your work. Therefore, your heart  rate is a delayed reflection of your work and of intensity. You might  recognize this: only after a few seconds of a 20 second sprint, your heart  rate goes up and you start to breath heavier. A heart rate monitor monitors  your response to the intensity, but not the intensity itself.

Furthermore, your  heart rate can be influenced by several other factors besides your work. For  example even thinking about the workout you’re about to do, can increase your  heart rate. Also tense muscles, dehydration, fatigue, illness, medication,  sugar and caffeine, hot temperature and humidity can increase your heart  rate. Women have a higher heart rate than men. And older people have a lower  heart rate, in general.

Therefore, a  heart rate monitor does not measure your intensity, how much work you have  done or if you’re making good progress based on measurable, observable and  repeatable data (Mad Dogg Athletics, 2017).

Don’t throw it away yet

Nevertheless, don’t throw your heart rate monitor away yet because it is a perfect tool to  measure power efficiency: how efficiently does your body responses to  the work. For example, if you power output (load, distance, time) on a  specific workout increases over time while your heart rate during that workout  is lower, you are getting stronger and fitter. But if your power output stays  the same over time while your heart rate is higher, you might be in a state  of stress, under- rested, dehydration or improper nutrition. And if your  power output decreases while your heart rate is higher, you might be  overtrained or ill.

Therefore,  training with a heart rate monitor can be useful. By registering your heart  rate over a longer period of time (resting heart rate, maximum heart rate and  training recovery heart rate) you can provide yourself with some additional  feedback on how you are doing. Measuring power output and power efficiency  can help to train more effectively and prevent overtraining.

Create your own  health!©