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With the ubiquity of Fitbits and other heart rate measuring devices, the title of this post has become a very frequent query on this forum and the answer is always the same……”Well, it all depends.”
That is a not a very informative response, so in this post we will look at the very basics of heart rate measurement and how it can be useful and also downright misleading to runners, if they do not understand those basic principles. It is not intended to be a guide to using heart rate monitors.
Your heart is a muscle that can be trained and developed to be more efficient at doing its job, which is to pump oxygenated blood from our lungs to all the cells of the body that require it to function. The circulation also removes waste material, such as carbon dioxide and returns it to the lungs for exchange.
We are all individual in our heart rates and the maximum number of beats per minute (bpm) will reduce as we age. Children tend to have a higher resting and maximum heart rate than an adult. Women tend to have higher resting heart rates than men. Very fit people tend to have lower resting heart rates and will also have a lower heart rate when working at the same effort as someone less fit, but not necessarily a higher maximum heart rate. Resting heart rates can range from below 40bpm to over 85bpm. Being at the extremes of this range can indicate dangerous conditions……..but again, not necessarily so. A maximum heart rate for an average 20 year old is calculated at approximately 200bpm and 135bpm for an average 85 year old. These averages are at the root of most cases of the title question and you can begin to see the complexity in a question that at first appears so simple.
Those average figures are calculated by many different formulae which are somewhat crude and only return averages. Most of us, by definition, are not average. The most common formula is 220 minus your age, used for the figures above. Another, slightly more sophisticated formula is 208-(0.7x age), which returns 194bpm for our twenty year old and 148.5bpm for the 85 year old. These formulae give you your theoretical maximum heart rate (MHR), upon which your heart rate monitor (HRM) zones will be calculated, which can be very useful for training, but only if they are accurate.
If your actual MHR is higher than this average, then the upper zones are not going to be true and your device may warn you that you have exceeded your MHR……….by definition, this is not possible if you are still standing upright. By the same token, if your MHR is actually lower than average, then you may well be working in a zone higher than you intend when you do your workout. The questions about MHR only ever get asked by those who are exceeding the estimates, while an equal number may well be working too hard, which is why the easy conversational pace is one of your best friends.
There are various training heart rate regimes, some with only three zones, but the majority of athletes work with a five zone system similar to the one set out below.
ZONE 1: Very light, 50-60% of MHR
ZONE 2: Light, 60-70% of MHR
ZONE 3: Moderate 70-80% of MHR
ZONE 4: Hard, 80-90% of MHR
ZONE 5: Very hard, 90-100% of MHR
For any established runner it is recommended to spend most of their running time (80%) at an easy conversational pace, which equates to approximately 70-75% of MHR and only push MHR to above 85% for about 20% of their running time. For any new runner, developing their aerobic base, stamina and endurance it is recommended to do all your running at an easy conversational pace. Pushing harder can be counterproductive and in extremes can actually damage muscle mitochondria.
So, I imagine you are asking, “How do I establish my actual maximum heart rate?”
My answer is that you do an internet search, because, for reasons of safety and liability, I am not going to answer that question. The best way to find out your MHR is to have a laboratory test with medical back up available, because this is a potentially risky venture. You will find alternative methods on the internet and if you decide to follow them then I would suggest that you have a responsible adult alongside you, should you require medical attention or resuscitation. This might sound overdramatic, but at least you won’t sue me.
In my view, you don’t actually need to know your MHR to train at different levels. The ability to speak aloud, clear ungasping sentences as you run, means that your breathing is optimal and consequently so will be your development of greater capillary density and more numerous mitochondria. At the upper end of this ability, as stated above, this is approximately 70-75% of your MHR and relates to Zone 2 to 3 above. As you get fitter the pace at which you can comfortably hold a conversation as you run will increase and you can use your HRM to identify this pace and track its progress. What you are looking for is trends.
Comparison of HR on different runs is only valid if you are working at the same degree of effort. So a level one kilometre run at a steady pace (after you have fully warmed up) can help show you changes in your development, if you repeat it methodically over time. Do not make the mistake of seeing one reading and believing that shows dramatic changes, when it may be caused by many other external influences, such as hydration, temperature, illness, drugs, state of restedness etc, or even glitches in the HRM itself. These devices can give misleading readings, so while they are a reference, they are not gospel. Even good quality equipment can deliver erratic results.
I used an HRM for a while and did the basic research when, at the age of 60, I found I could run quite happily for over an hour with my bpm in the mid 150s, which if I had believed the estimated zones, was right at the top of my range ……...over 95% of my estimated MHR………..clearly impossible and indicating that my actual MHR was considerably higher. I felt fine and recovered quickly afterwards, which is actually the answer to the question in the title……….your heart rate is only too high, probably, if you feel ill, light headed or feel palpitations after recording a high rate and you do not recover quickly. I no longer use one, preferring to listen to my body and be as tech free as possible.
While using an HRM to set zones can be very useful, especially for an elite runner, for the average recreational runner it is an unnecessary complication……….unless you are willing to do considerably more research into this complex area and get a fuller understanding of the mechanisms involved. Below are some of the resources I have used to research into this topic.
I also highly recommend The Runner’s Body by Ross Tucker, Jonathan Dugas and Matt Fitzgerald to anyone who wants to understand what is happening in their body when they run.
If you have concerns about your heart rate or how you feel while, and immediately after, running, then talk to your doctor.
There are more FAQ posts giving general information here healthunlocked.com/couchto5...