What is heart rate training

Training, September 12, 2020

This article discusses the benefits and limitations of heart rate training to help you train better and smarter.


Heart Rate Training, why is it important?


What is heart rate? - Your heart rate is the speed at which your heart is pumping the blood around the body, measured in beats per minute (BPM) and the higher the number, the faster the heart is beating.  This is typically measured by a heart rate strap or optical reader based on your GPS, which uses either electrical impulse measurement or infrared to detect the heart pumping blood around the body.  This is then shown on your training device as a number.  Most people have a resting heart rate between 60 to 100 BPM, and it is widely accepted that a lower heart rate at rest is an indicator of a more efficient heart.  This, however, doesn’t necessarily always equate to being fitter; various medical conditions or other influences such as fatigue, illness and even heat can influence your heart rate.  Heart rate is effectively a measure of how hard your body is working at any given time and what we would class as an input measure, or your input of effort to move or complete the task your body is currently doing, to put it another way, your heart rate tells us what level of intensity your body is working at.



Why is it useful? And What does it tell us? - Heart rate, for endurance athletes, tends to be used for recovery checking and training zones; we will focus on training zones for this article. Pace historically has been a way to measure the level of training and intensity you have been working at, but, unfortunately, pace has one big flaw.  If you were to work out your running pace zones and apply them to your sessions, you would end up with something similar to Zone 1 (11 min miles - 10:15 min miles, Zone 2 (10:15 - 09:30). Excellent, you now know that running at 10 min miles puts you directly in a recovery zone for your training allowing you to structure your activity to allow for some high intensity (pace) sessions and some long slow distance recovery or endurance building session. Using pace to measure this is fine on a flat track or flat roads, but what happens when we introduce hills into the equation or fatigue or weight gain/loss or weather conditions?  Your pace would be affected.  


Let's use hills as an example; running at 10 min miles on the flat will be much more comfortable than on an 8% climb and probably more difficult than running down that 8% hill, so we can see that using pace is very limited in its usefulness.  This is where heart rate starts become useful.  If you are to run at heart rate zone 2 (135-145 BPM, for example), you can modulate your pace/effort to stay within that heart rate band, meaning that you can control your body's effort much easier and monitor your training zones far easier than with pace alone.


How do we use it? -  One of the most user-friendly ways to use heart rate is to have a set of heart rate ranges relating to your level of effort, which can then be used to prescribe your training and allow you or your coach to set training sessions based around these ‘Zones’.  This means that your level of effort can be managed and that you can ensure you aren’t working too hard or taking too easy when the session demands it.  For simplicities sake, we use heart rate zones that Joe Friel developed as they fit well with the systems we use and, from our experience, are the most reliable and easiest to not only use but also set.  The most accurate way to set your heart rate zones would be in a physiology lab, with blood samples taken to define your Lactate Threshold Heart Rate (LTHR). This is the maximum heart rate at which your body can effectively deal with lactic acid (used for energy creation and not responsible for causing your body to fatigue, a discussion for another time) from the working muscles.

After this point, the body rapidly gets overwhelmed with lactic acid and other by-products and begins to fatigue.  This, as you can tell, is quite a crucial point; if we exercise below this, we can effectively run or workout for longer. If we go above it, we will soon either have to slow down or stop.  As lab tests can be expensive and difficult to get to, we can complete field tests to approximate this, as any test carried out in the field will be an approximation of lactate threshold, we would typically refer to this heart rate as Functional Threshold Heart Rate (FTHR) which is the average heart rate for a 60-minute race pace effort.


How do I find my Zones? There are many different ways to set your training zones, such as maximum heart rate, resting heart rate, and maximum or other variations.  However, these tests either require you to exercise at the highest intensity possible to gain your max heart rate or take a considerable amount of guessing (which leads to inaccuracies).  Don’t get me wrong here. How we find and calculate our zones is not by any means perfect, but it is a more accurate measure/estimation of your LTHR.  

To find your FTHR, we must first realise that this heart rate will differ depending on the type of sport you are doing. For example, running is a full-body activity where your muscles support your whole body mass. In contrast, cycling is partially supported by the bike and swimming is supported by the water (we will deal with swimming separately as there are some problems with gaining heart rate data in water), so we would expect that your heart rate would be higher in general when running than being partially supported when cycling.  These are factored in by having different zones for differing sports.

We calculate our zones for both activities with virtually the same test; this means that there are fewer things for you as an athlete to remember and keep as simple as possible, so we don’t have too many openings for the data be corrupted.


How do we test it? - We try to keep it simple here at TCC and use an easy to understand testing protocol widely known as the T-30 or Functional Threshold Test.  To complete the test, you should warm up thoroughly, taking between 15-20 mins of building effort to ensure you are fully ready to complete the test, then run or ride at your best maintainable effort for 30 minutes, making sure you are recording your heart rate, pace and cadence (if you have that functionality) once you have completed the 30 mins slow down and walk for until you have your breath back then complete a good cool down of around 10-15 mins.  You will now need to do some data analysis (it sounds complicated, but it isn’t), you will need to find the last 20 mins of your test (you can make this more manageable during the test by hitting the lap button on your GPS watch at 10 mins into the 30 min test and then again at the 30-minute point) and finding out what your average heart rate was for that section.  If you gave it your all during the test and didn’t speed up or slow down towards the end too much, you have just found your FTHR for that particular activity.  This number is then used to calculate your zone percentages listed below for running and cycling. 


Run Zones


Zone 1 Less than 85% of FTHR

Zone 2 85% to 89% of FTHR

Zone 3 90% to 94% of FTHR

Zone 4 95% to 99% of FTHR

Zone 5a 100% to 102% of FTHR

Zone 5b 103% to 106% of FTHR

Zone 5c More than 106% of LTHR

Bike Zones


Zone 1 Less than 81% of FTHR

Zone 2 81% to 89% of FTHR

Zone 3 90% to 93% of FTHR

Zone 4 94% to 99% of FTHR

Zone 5a 100% to 102% of FTHR

Zone 5b 103% to 106% of FTHR

Zone 5c More than 106% of FTHR


There we have it; you now have your training zones, but what do they mean? We have another article/video covering this in more detail; check it out if you want a more in-depth explanation. 


Are there any downsides to heart rate training?  - Yes and no, it's more of limitations to be aware of.  As heart rate is an input metric and directly related to how hard your body is working, many things can influence your heart rate both up and down.  For example, working out in a hotter than typical environment will mean your heart rate will be higher due to extra energy being used to sweat and allow for other bodily functions used to regulate heat.  Being tired or ill can influence your heart rate, too, as well as medications and caffeine.  So, although heart rate is a good way of measuring your intensity, it is by no means perfect.  The best approach would be to use pace, heart rate and perceived exertion to give you a clearer picture of how hard you are working, but to start using heart rate is a much more accurate approach than just pace alone!  One other limitation to be aware of is that your FTHR is not a fixed point. With more training, your heart rate may shift, which can change your heart rates for any given zone, for example, the fitter you become, the more efficient your heart becomes, and your average heart rate will become lower at a given intensity, so you should look at re-testing regularly (approx. 4-6 weeks) to ensure your zones are still accurate.