This article originally ran in spring of 2012.

As far as physical activity goes, running is the simplest one — but only at the beginning. Once you’re over the first painful phase of building up the stamina, once you’re able to run with ease and for a long time, once the first thought of running a race invades your mind — that’s when things get complicated. 

The most important decision you have to make is to choose a training plan. Your training can be based on distance, time, pace or heart rate. This last one is especially important for techie runners.

RELATED: What is resting heart rate and why should you monitor it?

While I don’t dispute the benefits of measuring the intensity of the workout based on heart-rate zones, I would like to point out some shortcomings of such training. But first, let’s remind ourselves what heart-rate training is.

Based on runner’s Maximum Heart Rate (MHR) and Resting Heart Rate (RHR), the training is divided across five heart-rate target zones:

1. The Fat Burning Zone — 50% to 60% of MHR — as the name says, training in this zone is ideal for drawing energy from fat cells by being low in intensity, but long in duration.

2. The Energy Efficient or Recovery Zone — 60% to 70% of MHR — training in this zone develops basic endurance and aerobic capacity, it’s ideal for recovery intervals.

3. The Aerobic Zone — 70% to 80% of MHR — training in this zone develops and improves cardiovascular system, especially the body’s ability to transport oxygen to the working muscles, and CO2 away from them.

4. The Anaerobic Zone — 80% to 90% of MHR — training in this zone will develop your lactic acid system: glycogen stored in the muscle is predominantly used as the source of energy, and a by-product of burning glycogen is lactic acid. A point at which the body can no longer remove the lactic acid from the working muscles is your anaerobic threshold. It is possible to train your body to delay the anaerobic threshold and increase the tolerance to lactic acid.

5. The Red Line Zone — 90% to 100% of MHR — training in this zone is possible only for short periods of time. It’s ideal for developing speed by working out fast twitching muscle fibers through sprint intervals.

To train by those intensity zones, you need a constant feedback on your heart rate, which you get by wearing a monitor. It consists of a belt-like strap which fastens around your chest and sends data to a display on your watch, or a smartphone.

I must confess: I don’t use the heart-rate monitor. I’ve tried it once and felt like an opera singer squeezed into a much too small corset. The hoop around the rib cage prevented my lungs from filling with air, and I couldn’t wait to take it off. But, some runners I know swear by it, listening to the beeps that tell them which zone they’re running through. Which finally brings me to point out what I think is wrong in all of the heart-monitoring strategies.

The whole concept of heart-rate zones is based on determining Maximum Heart Rate — which is as fast as your heart can beat. Without accurate MHR value, all the training zones become arbitrary. And before that, you need calculate the proper bpm value for each zone. A simple formula for that is: Target Heart Rate = [(Maximum Heart Rate – Resting Heart Rate) × %Intensity] + Resting Heart Rate

There are a myriad of formulas to calculate your MHR, but they are all based on average value. Since heart rate value is very individual, the MHR you get from a formula may wildly deviate from your real  heart rate. The most accurate way to find the MHR is through so-called graded exercise test, which could be costly even if you manage to find a facility that can provide it.

Further, many external factors can affect your heart rate: lack of sleep can raise the heart rate from 5 – 10 bpm (beats per minute); workplace stress will raise it by 4 – 6 bpm; caffeine elevates heart rate up to 24 hours after ingestion; hot and humid weather also causes heart to beat faster; dehydration can cause heart to beat 5 – 7% faster than normal.

All of these fluctuations in heart rate can cause your training to be seriously out of the zone you believe you’re training in. For example, since your Resting Heart Rate changes during the day, that also means your training zones change with it. So, if you don’t realize that your heart is beating faster than usual and re-calculate your training zones accordingly, you may believe you’re in the aerobic zone, while in reality you will already be hitting your anaerobic threshold in the higher zone. While such mistakes will only mean that you tire faster, in extreme cases you can overextend yourself by pushing too hard.

In conclusion: heart-rate training is a fantastic tool for elite athlete, because they have accurate measuring to start with, and specialists who can adjust their training zones based on daily fluctuations. Most of the rest of us don’t have resources to use it accurately. So, if you do train with heart rate zones, exercise caution and be aware of your heart’s fluctuations and the training’s limitations.


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7 Comments

  • Another factor you have to keep in mind is something called cardiac drift. The further you run, especially in hot weather, the more fluids you lose and the harder your heart has to work. As a result, when you run for a constant pace on level terrain, your heart rate will tend to gradually increase from the beginning of the run to the end, despite the fact that your pace and perceived effort are the same.

    Despite the limitations, I think heart rate training can help beginners to get a feel for the correct intensity for the various workouts, ie. easy runs, tempo runs and intervals, but more experienced athletes can and probably should run more by feel.

  • Andrew C says:

    Nice article but you clearly state that you have never trained using a heart rate monitor. Try it then report on it.

  • Guy Leclerc says:

    I am surprised to see an article like this in a running website. I train sometime to see how my training is going. You can also fin your MHR by running a 3k at full speed and you should reach, very closely, your MHR at some point.

    Yor exactly right that you HR will fluctuate for many reasons and you should stick to your zone. If you HR is higher that day vs your speed because you are tired. This is exactly a sign to slow down. Samething when your doing a long distance, you need to plan that your HR will increase overtime at the same speed. So you need to start slower so you can finish your training in the zone you were planning to run without reducing your speed at the end.

    Your article is missing the point vs training with an Hearth monitor. The elite runners are generally not running with hearth rate monitor. They are monitored with other techniques.

    I was happy to see the title and was looking forward to read this article. Unfortunately, I am disappointed and for sure will not share this article with any running friend. Sorry.

  • Thank you for comments, and I’m sorry if the article didn’t answer your questions. Just like with any type of training, there are many proponents and opponents of the heart rate training. As I said in the post, I don’t dispute the benefits of it; I actually like the idea of being able to improve a specific area by targeting training through appropriate zone of intensity, whether it’s weight loss through fat reduction, improving aerobic capacity or speed. A heart rate monitor may help guide a runner through different zones of intensity during workouts.

    I merely pointed to its limitations: there are too many variables and inaccuracies which can affect the outcome. It makes training with a heart rate monitor cumbersome – the training needs constant re-calculations and adjustments, or the user risks missing his target zones.

  • jmgleclerc says:

    It is exactly what I was trying to say. To my knowledge, You should not recalculate you zone when those factors affect your HR. let’s say that you are tired and you HR is higher than usual. You will train in the exact HR zone. For sure it will be slower, but that is what you body is asking…a little bit of rest. So, you keep training in your normal zone.

    • Hi Guy,

      I’m sorry you didn’t like the article, and allow me to point out that the opinion expressed is my own, not that of the Canadian Running magazine.

      I’m afraid you misunderstood me – I have nothing against the intensity zone training, on the contrary. I personally don’t trust HR monitor, and I pointed out why. Again, for all the people who like training with it – and I’m guessing that is your monitoring gadget of choice – there’s nothing wrong in following your zone training if it works for you.

      Running full-out 3k is a good way to gauge your approximate MHR. Although it’s still not entirely accurate, because it depends of external factors, the bigger problem is with the ever-changing RHR. While the zones may not shift dramatically, they do shift. For example, let’s say for the ease of calculation, if a runner’s mhr=200 and rhr=50, the target hr for 50-60% intensity zone is 125@50% to 140@60%. Now let’s imagine that same runner had too much coffee that day, or for any other reason his RHR rose to 60, then his target HR for the same zone is 130@50% to 144@60%. It may not seem significant, but it can mean a difference in training.

      The elites, as you pointed out, don’t use HR monitor, but they do the intensity zone training, in different variations. They run by feel, and for monitoring, they usually use blood lactate levels, which are supposed to give more accurate info. Jeff Gaudette, a USATF certified coach and author, talks about it in his article here: http://running.competitor.com/2012/02/training/three-reasons-to-rethink-heart-rate-training_47287/3

      At the end, no matter which system you use to monitor your training, I hope it brings you to your target level.

  • jmgleclerc says:

    And a quick question, how can you be better in you zone without a HR monitor?

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