Heart Rate Training – Why You Should Do It

I use heart rate training as a tool to slow runners down, not to speed them up. I think it is the most reliable and accurate way to achieve that goal.

There has been a lot of research over the years proving that the most successful training intensity ratio leading to stronger, faster and healthier runners is 80% “slow” and 20% “fast”.

Slow - means training aerobically or at a relatively low heart rate. During aerobic running you burn fat as your main source of energy. Aerobic training doesn't put as much stress on your body as anaerobic training and you don't need as much recovery time between training sessions, therefore you are less likely to suffer from injury or illness if the bulk of your training is aerobic. Your aerobic system provides a solid foundation for good health.

Fast - means training anaerobically or at a relatively high heart rate. Anaerobic training puts a lot more stress on your body. It puts more stress on your muscles and joints because you are running at a faster pace. Anaerobic training sessions, like hill repeats or 1km intervals, take longer for your body to recover from, therefore, your training program needs to be structured to allow enough recovery time after these sessions to minimise the risk of you getting injured or sick.

The biggest mistake made by most recreational runners is that they inadvertently train to a ratio of 50% slow and 50% fast, which limits the effectiveness of their training in terms of race results and overall health. Too much “fast” training causes stress on the immune system and general fatigue which makes runners more susceptible to illness and injury.

We have a 12-Week Base Training Plan that combines low heart rate training, strength and stability workouts and a gradually increasing running volume. This plan is perfect for anyone wanting to learn more, and benefit from improving their aerobic running capacity. It is also  a perfect "between race" training block to build stronger foundations before your next event.


Why not use pace instead of heart rate?

In terms of exercise intensity, running to a specific pace only works on flat terrain and in specific weather conditions. For example, if your “slow pace” is 6mins/km, running up a hill at 6mins/k is a lot harder on your heart and lungs (and heart rate) than running down a hill at 6 mins/k. Your intensity level would be constantly changing if you were running on a hilly route and trying to maintain a steady speed. This might therefore turn your “slow” run into a “fast” run.

Runners often let their ego get in the way of sticking to a slow pace. Even choosing a flat course for a 6 mins/k run, a lot of runners will speed up towards the end thinking “I usually run 5mins/k, 6 mins/k is too easy, so I’ll do 5:30’s instead.”

Ambient temperature and humidity have a significant influence on your intensity levels. If you were to run on a flat course at 6 mins/k at 31 degrees Celsius, your heart rate will be approximately 20 beats/minute higher than if it was only 21 degrees Celsius. This again makes pace unreliable as an indicator of how hard you are pushing your body.

Running at a “conversational pace” or a pace you can “run all day” are terms which are often used to describe “slow” running. These descriptions, or queues, work well for some runners, but over the years I have found that most runner still manage to misinterpret them and inadvertently end up closer to the 50/50 ratio rather than 80/20. If you have always run too fast, then your definition of “slow” often isn’t physiologically slow.

In my experience, and also the anecdoatal evidence from many coaching books that I have read, it is easier to get most runners to consistently stick to a specific heart rate number than to pace or perceived exertion. It seems that runners find it easier to “justify” running at a heart rate of <140bpm for example, than they do to run at 6 mins/km. I think this mainly comes down to ego. Runners often think they are “better than” 6mins /k.


Should you always run to heart rate?

I think that the long-term goal of running to heart rate should be to gain an understanding of how your body functions, and how running at different intensities, effects your body differently. If you run harder, you tend to get tighter muscles and more niggles after a run, and it takes you longer to recover. If you stick to easy “slow” runs, you recover much quicker, and you can therefore train again sooner with less risk of niggles or injuries hampering your progress.

Over time, by using a heart rate monitor, and being aware of your body and how you feel when you run, you should start to gain a good understanding of “fast” and “slow”. Eventually you should be able to use “perceived exertion” as a reliable way of gauging your intensity level.


What heart rate should you run at?

This is perhaps the most confusing element of heart rate training. It seems that every coach, author, and sports scientist has a different formula you should use, or a different recommendation for determining your heart rate zones. It also seems that they have a different way of interpreting the zones in terms of what is “slow” (aerobic) and what is “fast”(anaerobic).

Here are two examples I found on what I consider to be good websites.

You can see from these two examples that there are not only a different number of zones, but in the first example the aerobic zone appears to be zone 2, or is it zone 6?, and in the second example it is zone 3. The percentages of MHR (maximum heart rate) are also different, making these zones even more difficult to interpret.


Why use the Maffetone Formula?

In my training programs I recommend using Dr Phil Maffetone’s 180 formula to calculate your aerobic (“slow”) training zone.

This formula is not 100% accurate for every single runner, in fact I think it comes up with a fairly conservative estimate almost every time.

For the purposes of developing an aerobic base and maximising the amount of running you can do while staying healthy and injury-free, running well within your aerobic zone is much better than running slightly outside it. So there is little room for error using this  formula.


What is Zone 2?

I believe that the intention of the Maffetone Formula is to keep you in what most tables refer to as Zone 2. This  includes the two fairly confusing tables above.

Zone 2 is the minimum intensity required to give an endurance training adaption.

The adaptations that occur with this level of training include:

  • increased stroke volume (amount of blood pumped per heartbeat)
  • increased oxygen transport in the blood
  • increased blood volume
  • increased ability of the muscles to use oxygen
  • increased capillary (blood vessel) density within the trained muscles
  • improved use of fat as a fuel, thus teaching the muscles to conserve the limited carbohydrate (glycogen) supply

Zone 2 is therefore not necessarily your aerobic threshold, or the absolute top of your aerobic zone.

Zone 2 would be better defined as the intensity at which you will gain the most benefit in terms of the training adaptations outlined above, with the minimal risk of creating excessive fatigue or sustaining injuries.

The purpose of including a base training (aerobic running) block in your training is to build strength and endurance. By sticking to zone 2 you will maximise the number of kilometres you can run each week whilst staying strong and healthy. This will allow you to slowly but consistently build your mileage.


Good news - Running “slow” gradually becomes faster

Runners who are either new to running, or new to aerobic running, often find it very difficult to stay within zone 2. They often have to walk frequently in order to keep their heart rate low enough. It takes time to develop a strong aerobic system, and the only way to do it is to train within your aerobic zone.

If you fit this category, and you are becoming frustrated and feel like Zone 2 doesn’t “work for you”, be patient. IT WILL WORK. 

It is amazing the number of excuses I have heard as to why the formula shouldn’t apply.

“I have always had a high heart rate”

“I’ve been a bit stressed so it is bound to be high”

“I’m too old to use that formula”

“It is hot where I live so I can’t keep my heart rate at that level”

None of those excuses hold up. Aerobic (zone 2) training works for everyone. You just have to be patient, park your ego, and stick with it until it works.

Over time, as your aerobic system develops, your speed will increase at your zone 2 threshold, possibly to a point where you prefer running well under your zone 2 threshold, because it requires too much effort to reach it!


Lactate Threshold Testing

Maffetone’s 180 formula, in my opinion, is generalised in a conservative way to ensure every runner will remain within zone 2. If you want to find out your exact specific training zones you can get a lactate threshold test done by a sports scientist or exercise physiologist.

What has become apparent to me recently, is that even the results of these tests are interpreted differently. If you ask your tester for your maximum aerobic heart rate, it might be defined as your anaerobic threshold and the number they give you might be the top of zone 3 or even zone 4.

If you do go down the Lactate testing route then in most circumstances you need to look at your Zone 2, and use the top number in that zone as your maximum aerobic training threshold.


Don’t sweat the small stuff

The purpose of running to a low heart rate is to make you healthier and help to reduce the stress on your body. Sometimes heart rate training can make you feel like you are becoming a slave to the heart rate monitor. This can increase your anxiety levels and takes the joy out of running. This shouldn’t be the case.

If your aerobic training heart rate is 140, it isn’t going to be the end of the world if it gets to 145 before you notice it. But if it does get to 145, then stop and walk until it is down to something like 125-130 so that it gives you the opportunity to run for a while again before it gets near 140.

If you are running down a hill and your watch or chest strap are jiggling about and the reading says 175bpm, but you feel like you are barely breathing, then the chances are it is a little glitch in the technology which normally sorts itself out at the bottom of the hill. If you are suitably concerned, then stop for a few seconds and check your pulse manually just to make sure.

Running to a low heart rate will ultimately make running fun, because you can run further, and more often than ever before, without feeling like your body is near breaking point.


Running Slow Doesn’t Make You Slow!

A lot of runners’ fear that if they run slow all of the time they will “forget how to run fast” or “not be able to run fast” or “lose their speed”.

None of those things will happen.

Training slow allows you to train consistently. It allows you gradually build up more and more mileage and make your body stronger. Once your body is stronger it will then cope with, and benefit from, the 20% fast training that you can incorporate in the lead up to your goal events.

Base training is like laying the foundations for a house. If you want a house to last for hundreds of years and stand up to any weather conditions it needs to be built upon very strong and stable foundations. If you build a house straight on the dirt, it doesn’t matter what material you make it out of, it isn’t going to last beyond the first few storms.

If you do speedwork and high intensity training before you have laid some decent foundations, it doesn’t matter how good your engine is, your body won’t last beyond the first few races!


Don’t believe everything your watch tells you!

A lot of GPS watches and fitness devices give you statistics like your VO2 max, your current training status and they like to tell you whether you are gaining or losing fitness. If you are in a base (aerobic) training block. Those statistics are irrelevant. They don’t take into account your overall health or your likelihood of getting injured. When you are base training you aren’t trying to increase your VO2 max. If you can remove that information from your watch, then do it. At least temporarily. If you can't see it, you can't worry about  it.


Consistency, Consistency, Consistency

Most runners get trapped in this cycle:

  • Train Hard
  • Get a niggle
  • Rest for a bit
  • Train hard again
  • Get injured
  • Rest for a long time
  • Get frustrated by resting for a long time
  • Train hard again to catch up
  • Get a niggle
  • . . .

Depending on what research you read, up to 70% of endurance runners get injured every year. Don’t become another statistic. Train slow, build some foundations and race fast.


Try  our 12-Week Base Training Plan that combines low heart rate training, strength and stability workouts and a gradually increasing running volume. This plan is perfect for anyone wanting to learn how to use heart rate as a training tool. You will finish this 12-Week Plan feeling strong and healthy, with an improved aerobic capacity and therefore the ability to run faster for longer.