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  • Writer's pictureAsh Radford

How to most effectively use a heart rate monitor

Updated: Oct 11, 2021

It seems like every 2nd person has a Fitbit on their wrist these days. They can supply a plethora of data about your body’s function but to me the most important and useful information they provide is your heart rate.

Heart rate monitors have been commonplace for committed exercisers for over 25 years but what are the advantages of using them?

The main reason for investing in and using a heart rate monitor is to train in specific heart rate zones in order to exercise at an effective yet sustainable intensity.

These various heart rate zones are defined by percentages of your maximum heart rate. Note that heart rate is simply how many times your heart beats in a minute (BPM) otherwise simply known as your pulse.

Your heart and exercise- the basics The harder you work (intensity) the faster your heart will need to beat in order to satisfy the demands of the muscles for oxygen, which is transported via the bloodstream.

Your heart is a muscle so like your other muscles, as your fitness increases over time your heart becomes bigger, stronger and more efficient. It effectively pumps out more blood and hence more oxygen with each contraction. This means it will beat less often than previously to perform the same intensity of activity. (The amount of blood pumped by the heart in each beat is called the Stroke Volume).

In addition because of this increased strength and efficiency, resting heart rate will be lower. It can supply oxygen needed to sustain resting function with less frequent pumps.

Another way your heart adapts to exercise is that not only is it able to pump out more blood and oxygen with each contraction, it also becomes capable of beating more often i.e. you have a higher maximum heart rate. This will become relevant as you read on.

The accepted heart rate zones to train in. Polar is a very well established heart hate monitor brand and they have fairly conventional guidelines around the 5 training zones, which are: * Very light 50-60% of maximum heart rate * Light 60-70% of maximum heart rate * Moderate 70-80% of maximum heart rate * Hard 80-90% of maximum heart rate * Maximum 90-100% of maximum heart rate.

Your overall goals and the duration of each of your workouts would then dictate which zone you’d train in.

For the endurance needed to finish a marathon it’d be necessary to do some long runs in the very light- light zones. Conversely if you were trying to run a faster time over 3-5 km's you’d more than likely need to do some shorter training sessions in the hard zone.

As a general rule for training intensity you can observe the saying “You can train long or hard but you can’t do both”. There are other factors which create more context as to what training zones you need to include in your overall training schedule and that won't be covered in this post but you can read more about it in this one- How hard do I need to exercise?

Maximum heart rate- how do you figure that out and is it worthwhile bothering? Now your maximum heart rate is calculated by subtracting your age from 220. Thus a 40 year old’s maximum heart rate would be 180bpm (220-40=180bpm).

This method is based on the assumption that your fitness will decrease with age, which is only a relative truth as a fit 60 year old can run rings around an unfit 20 year old.

Another limitation with this method is that maximum and resting heart rates (& active for that matter) are also largely determined by genetics. While your heart’s function will still be impacted by your level of activity there are big variations in heart rate from person to person. I have trained 40 year old’s who can hold a conversation at 170 bpm while others of the same age are gasping for breath at 130bpm. Clearly there’d be a big difference in maximum heart rate among 40 year old's. The conventional way of establishing maximum heart rate is very rough indeed but some form of guideline is needed, so it’s the accepted process.

An alternative is to find out your maximum heart rate through a graded process whereby you exert yourself at an absolute maximum intensity level after having already reached a degree of fatigue. Clearly that involves exercising really, really hard. Not a lot of fun and also potentially dangerous for the unfit or those with an undiagnosed, underlying health condition. In short there’s not a lot to be gained from such a process because……….

The important thing to know about your maximum heart rate is that it's NOT important to know!

I’m not at all interested in the maximum heart rate of my personal training clients nor my own. It’s just not that useful, I'll never push someone so hard they reach it.

Having said that during a small group session I was interested and somewhat alarmed to see a fairly unfit 40 year old male get his heart rate to 212bpm. This showed me a few things: firstly that he was stressed, secondly that he was probably pushing himself to impress his boss he was training with, thirdly he had a naturally high heart rate and most importantly that he needed to be told to slow down as there wasn’t really anything to be gained by going so hard.

In essence maximum heart rates vary so widely from person to person, irrespective of age, that I’ve found trying to figure them out to be a waste of time.

How then do you workout what zones to train at? Given heart rate monitoring is regarded as pretty scientific I’m going to conversely suggest a very unscientific way of figuring it all out, try this: with your heart rate monitor on do some form of cardiovascular activity at what you’d rate as a 7 out of 10 intensity (10 being maximum effort) continuously for 20 minutes. If you do this properly, once you’ve gotten warmed up, your heart rate should stay within a 15-20 bpm range.

You could now consider that your moderate zone. As time goes by and you get more familiar with how your hear rate responds to various exercise intensities you could refine that moderate zone.

Now I like to keep it nice and simple and just have 3 zones- high, moderate and low. For my own training at the moment I regard low as 115-130bpm, moderate as 125-140bpm and high as 135-150bpm. Note that If I were to use the conventional calculations and methods described above (age 45 years) the range of the equivalent zones would be much broader (Low/moderate 105-122bpm, Moderate 122-140bpm and hard/high 140-157bpm)

I have an overlap between the zones as I find in practice that the spread of the intensity using the conventional method is too broad. 105bpm just doesn’t feel a worthwhile intensity to train at and I also know that for me working at above 150bpm is hard work, uncomfortable and very hard to sustain for longer than a few minutes. If I do try and maintain that level for more than a minute or 2 it’s very hard to then complete the session at any degree of significant intensity.

During personal training sessions I regularly ask and check my client’s heart rate and due to having done thousands of sessions over the years I just get to know what each person’s zones are and can often make a pretty accurate guess (well it’s a professional estimate really) at what their heart rate is during, or immediately after a particular activity.

In essence you are trying to get familiar enough with your heart rate so you can then train at a sustainable level which is also demanding enough to cause your body to adapt and change, which is basically the name of the fitness game!

The fat burning zone myth There is a belief if you train at a very light intensity you are maximising the burning of fat. Depending on what you read this is somewhere between 50-70% of maximum heart rate. It is indeed true that at lower intensity you utilise a greater percentage of fat as fuel (relative to carbohydrate). HOWEVER, the higher the intensity you go the more of everything you burn i.e. you do more burn more carbohydrates (glucose) as both a percentage of total energy burned and total amount of carbohydrate burned but you also burn more total fat. It is simply a case of whoever burns the most calories/expends the most energy wins. This is not to mention a greater rise in metabolic rate as a result of high intensity activity, which remains raised for an extended period after the workout.

Low intensity zone is still useful though As explained though if your goal is to increase endurance you need to keep the intensity nice and low in order to be able to go for longer. Lower intensity is also often most appropriate for a beginner trying to establish a routine or someone returning to exercise after a lay off. In both examples it can be really beneficial to avoid discomfort and limit the likelihood of muscle soreness till you get into the habit. Sometimes it’s wisest to try and make the exercise experience relatively pleasant. For a more committed exerciser low intensity can also be used as method of recovering from the previous days hard workout while still adding to the total training volume which can be needed in preparation for a lengthy endurance event.

The little known benefits of consistently monitoring heart rate By using a Heart rate monitor regularly you become adept at noticing any differences in Heart Rate, this is true for both resting heart rate and during exercise. If it's higher than usual it can be due to fatigue. This provides an opportunity to reflect on the quality and quantity of sleep the previous night. Most importantly though it means you can adjust your training intensity accordingly, this could be done by either staying in the intended heart rate training zone, even though the resistance/speed/intensity is lower than usual or you could choose to train at a lower heart rate zone than initially planned.

Sometimes it’s even wisest to not even do the training session at all or just go for a gentle walk (that’s happened in plenty of personal training sessions).

You can take this process of observing resting heart rate further by monitoring your heart rate every morning or night to give an indication of how well recovered you are from previous training sessions, then of course you could train harder/longer more/less according to your degree of recovery (higher HR= not recovered, lower HR= more recovered)

In fact through regular use of a Heart Rate monitor a client and I were able to identify an irregularity in heart rate which was cause for a visit to the doctor and eventually surgery. More than useful information!

The downsides of always using a heart rate monitor.

Of course it is possible to train effectively without monitoring your heart rate, many champion athlete’s have and will continue to. There are a few pitfalls to be aware of with heart rate monitoring:

You can become really fixated on the numbers and limit yourself from going at an all out level for fear of something going wrong or that you’ll hit the metaphoric wall and won’t be able to continue. (This may seemingly contradict the how I described not being able to continue for long if I get my own heart rate above 150bpm but if you read on you’ll find my view on race day expands on this and the same can apply to some training sessions). You can also get anxious if your heart rate is higher than you think it should be and start to think negatively about it. I’ve also seen people get annoyed and a little anxious when they aren’t getting an inaccurate reading, this can create all sorts of doubt and worry- if you let it! (A good way to tell if it isn’t giving an accurate read is to closely watch the flashing heart symbol on the screen, if it isn’t beating consistently its more than likely giving an inaccurate read which you can disregard, although if this is happening on a regular basis you probably need to give it more thought and perhaps start by doing some manual pulse checks). There can be interference from other electronic devices and also when your skin is cold it doesn’t function as well. You can then spend a lot of time and energy trying to get it working. Often it’s best to just get going and after a few minutes it’ll sort itself out.

If you are training for an event a good plan can be to wear it for most training sessions but not worry about it during the actual event. During an event you are usually looking to perform at an intensity above what you would during training and coupled with the nerves and atmosphere it can send that heart rate up considerably higher than normal which can be cause for worry that’s not needed. You could regard an event or race as ‘special conditions’ under which your body is capable of going beyond the ordinary!

Having suggested that, I must admit I have been wearing one during 5-7km races, however I restrict myself to only 3 looks while running, knowing I can access information about the average average and maximum heart rates during the race. While the post race analysis of heart rate is interesting, my main reason for wearing it is so I don’t get carried away trying to keep up with others going up hills and then not be able to go at anything close to my desired race pace. Due to the way I train I know I can speed up over the last kilometre or so and mow people down but not if I’ve used up my fuel dashing up hills. During the last 1 kilometre effort I really don’t want to know my heart rate, besides which I’m concentrating and trying so much I don’t want to glance away from where I’m stepping for an instant.

Chest strap V wrist and battery replacement I have to concede I’ve no experience with the devices which pick up your heart rate from your wrist nor for that matter the latest ear bud versions, as all of my experience is based around chest straps, which are generally regarded as being more accurate than the wrist based style.

Something to consider when buying a monitor is how you go about replacing the batteries as some you need to send back to the manufacturer, which can be a time consuming pain. The way in which the battery is replaced can also effect if it remains waterproof/resistant. I should add that there is also a battery within the chest strap- not just in the watch!

So there you have it, an exhaustive guide around the effectiveness of heart rate monitors, hopefully that provides you more clarity and information around how best to use them.

If conversely you’re now overwhelmed or have any questions about heart rate monitors or training in general get in touch and I’ll do my best to help. I also offer truly individualised training programs for weekend warriors of all levels and those seeking to get underway with a fitness routine. Plus my mobile personal training service means I can caome to your home or nearby park if you live in 1 of the following northern Sydney suburbs: Frenchs Forest, Belrose, Davidson, Terrey Hills, St Ives, Forestville, Killarney Heights, Roseville, East Linfield, Seaforth, Mosman


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