Using a heart rate monitor for training and racing has many benefits, and this article sets out to help you get the best out of using your heart rate monitor to optimize your training. But there are some limitations in using heart rate monitors, and this article will also explain them. Let’s take a deep dive into heart rate training. 

I am of the old school of runners, having run my first ultra marathon back in 1977 at the age of 15, and even in my peak racing years in the 1980s, there were no gadgets such as GPS watches or heart rate monitors. There was life before Strava, and I have logbooks going back to 1975 to prove it.

Let’s unpack the benefits and limitations of heart rate training, before discussing how best to use them.

Benefits of heart rate training 

When heart rate monitors came out in the early 1990s, it was revolutionary. I was fortunate enough to be sponsored with a Polar heart rate monitor back then and I was fascinated, as I has already for years been measuring my heart rate by putting a finger on the pulse on my wrist for 15 seconds and then multiplying it by four. 

Suddenly I could strap on a heart rate monitor and have instant readings on what was happening inside my body. Before then, most us did not know the theory of using heart rate zones, and ran on feel.

Perhaps the biggest benefit in using a heart rate monitor is that we can use it to prevent us from running too hard. One of the biggest mistakes that I see as a coach, is runners pushing too hard on their easy runs. If we consider that about 80-90% of training should be done at an easy pace, we can see the potential for making sure that we don’t overdo it on easy days. 

A further benefit is in racing, especially in the early stages of a race. Even on ultras such as the Comrades marathon or the Two Oceans , it is easy to get carried away by the vibe and start too fast. Using a heart rate monitor can keep you in check in the early stages when it is needed. 

Using a heart rate monitor is also useful for steady pace runs such as tempo runs and marathon pace runs. On these runs the benefit is that they prevent a runner from trying to push too hard on the climbs. 

Know your resting heart rate 

Runners know that a low resting heart rate is good and in my 20s, mine was 31 beats per minute, which was extremely low, as it would go DOOF … PAUSE …. DOOF. My low resting heart rate would often stress the doctors at my annual medical check up, until they realized that I was a runner.

Even now at the age of 63, my resting heart rate is 52, which is still quite low. Our resting heart rate gradually increases as we get older. To measure your resting heart rate, you can check it upon waking before getting out of bed.  Runners that sleep wearing their smart watches will already have this data.

Check your maximum heart rate

Runners are often unsure of their maximum heart rate, and it is important to note that it can vary between people of the same age. 

A higher heart rate maximum means that a runner can push more blood through the heart and blood vessels, and therefore more oxygen. Sadly our maximum heart rate gradually declines by about 10% every decade. 

NOTE: Some runners have unusually high heart rates in training, even when feeling fine. I have a few runners like this, and I normally suggest that they go to a cardiologist for an ECG and opinion. In all these cases, my runners have been cleared to run as normal. But if in doubt, see your doctor or a cardiologist.

In the past, runners would try use the  220-age formula devised in 1970 in the USA by Doctor William Haskell and his mentor, Doctor Samuel Fox. 

The doctors were attempting to determine how strenuously heart patients could safely exercise. They drew a line through the data and noticed that at age 20, the heart rate maximum was 200, at age 40 it was 180 and at age 60 it was 160. Doctor Fox then suggested the formula of 220 minus age.

But they used data from studies of smokers or people with heart disease, who were not representative of the general population, let alone well-trained runners. Very soon this formula was adopted by the sport industry, which used the 220 minus age rule of thumb for several years. This is not an accurate rule of thumb, and is best not used.

Most runners use GPS watches, and can use the maximum heart rates shown on your data from years of running. But for those who would like to be more exact, the best method is to run at maximum effort to check your maximum heart rate. There are two sessions for this that I use for runners, and you can use either of these. Try to make sure that you are rested before doing this max heart rate test, and do a good warm up jog before and a warm down jog afterwards.

NOTE: these sessions are best for trained runners and not beginners.

1.  Do a 5km time trial or parkrun quite hard, but not maxed out. You want to be quite tired going into the last kilometre, but still with some energy to push. Then in the last 400 metres, start to wind up the pace so that you reach your maximum possible speed in the last 100-200 metres of the 5km. At this point you should hit your maximum heart rate.
2. Do 3 x 800m with a 200m jog between the intervals as recoveries. Then on the last interval gradually pick up the pace so that you hit maximum possible speed in the last 100-200 metres of the 800m. At this point you should hit your maximum heart rate.

Understand your heart rate reserve

Ideally a runner would have a low resting heart rate and a high maximum heart rate. But as we get older, we get squeezed on both ends, with our resting heart rate rising and our maximum heart rate declining. This is one of the reasons why we get slower as we age.

In other words, we are saying that the bigger the difference between your resting heart rate and your maximum heart rate, the better. This difference we call your heart reserve or working heart rate. 

Using the Karvonen formula for heart rate zones

Once you know your resting heart rate, maximum heart rate and heart rate reserve, we can calculate the percentages for the heart rate training zones using the Karvonen formula. 

Karvonen formula: Heart rate reserve x (required %) + minimum heart rate = heart rate 

For example, to calculate 85% of maximum heart rate for a runner that has a maximum heart rate of 180bpm and a resting heart rate of 60bpm and a heart reserve of 120 (180-60 = 120), the calculation is: 120 x 85% = 102 + 60 = 162bpm.

NOTE: If you do this calculation without using the Karvonen formula, then 85% of maximum heart rate of 180bpm = 153bpm, which is a lot less. It is for this reason that when calculating heart rate zones, we need to know the resting heart rate, maximum heart rate and heart rate reserve.

How to use heart rate zones 

Most GPS watches as well as Strava, show five training zones and they are colour coded.  The five zones are:

1.  Easy pace at 50-60% of maximum HR
2. Easy pace/steady pace at 60-70% of maximum HR
3. Tempo threshold pace at 70-80% of maximum HR
4. VO2 max at 80-90% of maximum HR
5. Speed at 90-100% of maximum HR

Coach Neville’s heart rate zones for runners

The above heart rate zones are aimed at the general population, but regular runners can usually maintain higher percentages than these. Many runners using the above percentages will find that the runs feel too slow, and their training won’t be optimal. 

For this reason, I use slightly higher percentages, with the training zones becoming smaller as they get harder. Jack Daniels, the renowned coach and author of the Running Formula, does the same.

If you are an experienced runner try use my heart rates zones (TIP: you can adjust your zones on most GPS watches). 

1.  Easy pace at 65-75% of maximum HR
2. Easy/steady pace at  75-85% of maximum HR
3. Tempo threshold pace at 85- 90% of maximum HR
4. VO2 max at 90-95% of maximum HR
5. Speed at 95-100% of maximum HR

NOTE: Zones overlap and at time you will be fluctuating between two zones.

 Zones 1 and 2 are easy to steady pace (marathon pace), and most runs will be done in these zones. This includes long runs, recovery runs and easy runs. But on hilly routes, a runner will fluctuate and go up to zone 3 on climbs sometimes, and that is fine. Zone 2 is your target zone for marathons.

Zone 3 is threshold running with tempo runs. These are what we call “comfortably hard” at about 15-21km race pace. They are ideal for tempo runs on 5-8km time trials. This is also your target zone for half marathons

Zone 4 is for VO2 max sessions which corresponds with your 5km race pace, and can also be used for flat out 5km time trials and long intervals such as 1km.

Zone 5 is speed and we use that for short, high intensity intervals of 200m-400m

Drawbacks to heart rate training

There are a few drawbacks to using heart rate training, and it is good to understand the limitations. 

Cardiac Drift

American runner, Alberto Salazar, was the upset of the day at the 1994 Comrades marathon when he took the lead early on up Fields Hill and ran away to win the race. Tracking him was the 1991 Comrades down run winner, Nick Bester, who was using a heart rate monitor for the first time.  Nick noticed that his heart rate gradually kept rising the further that he ran, and he therefore slowed his pace to keep in his target heart rate zone. The result was that by the time he reached the climb up Polly Shortts, he was feeling great, but had run out of road to catch Salazar. Nick ran his 8km PB on the last 8km that day, to take second place. But I have no doubt that he could won he had he ditched the heart rate and listened to his body instead, and used Perceived Effort.

Cardiac drift is the gradual rise in our heart rate on a long run. Our core temperature rises, and the stroke volume of our heart decreases (the amount of blood pumped per heart beat). But the heart rate increases to make up for this, so that essentially the same volume of blood is being pumped. 

NOTE: on hot days our core temperature rises much faster than usual, and we will have to slow down.

Cardiac Lag

When we suddenly increase our running intensity as on an interval or on a hill, there is a time lag before our heart rate catches up to our increased effort. For instance, on a 200 metres interval, your heart rate may only reach the desired heart after perhaps 100 metres, even though your pace is correct. This means that heart rate is of limited use on short intervals. But is can still be used successfully on longer intervals. Monitoring heart rate in the recoveries is an excellent way to ensure that you recover properly and it works well for this. A good rule of thumb for recoveries is to let the heart rate drop to 120bpm between intervals, but listen to your body, as this may not work for all runners.

Putting it all together

Use the amazing technology that we have, but always remember that they are tools with limitations. Some runners are fixated on using heart rate in training, but not understanding cardiac drift and cardiac lag, while some are fixated on pace using  their GPS watches, but not accepting that pace will vary, and be faster on downhills and slower up hills.

Many runners will already be using their heart rate monitors based on the running data on their watches, and if the training intensities on the zones feel right, then that is fine. But some runners may want to tweak their heart rate training by adjusting the zones and checking their maximum and minimum heart rates as explained in my article. 

Ideally a runner will use Perceived Effort (how she feels), while keeping an eye on heart rate and pace. Sometimes we hit the sweet spot where all three are aligned, but don’t stress when they don’t. The important thing is to listen to your body, monitor your breathing and how you feel, and use heart rate where it works well.

Coaching