What is heart rate training
Training, September 12, 2020
In this article we discuss 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 basically the speed at which your heart is pumping the blood around the body, it is measured in beats per minute (BPM) and the higher the number the faster the heart is beating. This is normally measured by a heart rate strap or optical reader based in 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, 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 like Zone 1 (11 min miles - 10:15 min miles, Zone 2 (10:15 - 09:30) and so on which is great as you know that running at 10 min miles puts you directly in a recovery zone for your training allowing you to structure your training 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 even weather conditions? Your pace would be affected.
Let's use hills as an example, running at 10 min miles on the flat is going to be much easier than on an 8% climb and probably more difficult than running down that 8% hill, so we can see quickly 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 bodys 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 were developed by Joe Friel 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 completing some testing with blood samples being taken, which would define your Lactate Threshold Heart Rate (LTHR) which is the maximum heart rate at which your body can effectively deal with lactic acid (which is 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 an important 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 normally 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 in which you can set your training zones such as maximum heart rate, resting heart rate versus maximum or other variations of this. However, these tests either require you to exercise at the highest intensity possible to gain your max heart rate or take a huge amount of guessing (which leads to inaccuracies). Don’t get me wrong here the way in which 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 be different depending on the type of sport you are doing, for example running is a full body activity where your whole body mass is supported by your muscles, whereas 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 less things for you as an athlete to remember and keeps it as simple as possible so we don’t have too many openings for the data to 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 fully 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 really isn’t), you will need to find the last 20 mins of your test (you can make this easier during the test by hitting the lap button on your gps watch at 10 mins in to 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 which are listed below for both running and cycling.
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
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, its 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 normal 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 and 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.