Matters of the Heart – Maximum Heart Rate (MHR)

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On my night run tonight. 5km at Zone 2 77% MHR
or hard but still able to talk

I talk a lot about Maximum Heart Rate and depend on My Polar FT60 Heart Rate Monitor considerably to monitor my training and physical activity. You can say that it’s the most important training aid I have. A friend of mine pointed out to me that all this tech talk may be lost on people so I decided to write a short note on what I mean. I had written about it an earlier post. This post is a monumental attempt to write down what I know about it. I’m sure there are other better resources out there (and I suggests you find it). You can call this post the first step.

Our heart beats at a certain rate per minute. How fast it beats depends on our general level of fitness as well as the physical activity we are in engaged in at that time. When we talk about Maximum Heart Rate (MHR) it is the absolute maximum rate that our heart beats per minute. It is absolutely crucial that we now what our MHR is so that we can train better. How to find out? You can go to special sports centres who will put you a series of tests to determine your MHR. Me? I just used a general formula:


MHR=220 less age

So my MHR is 220 less 40 which is 180. This is a very very rough rule of thumb and there are a lot of literature out there critical of it. But it’s a start. I have noticed that my Polar FT60 HRM sometimes register 120% MHR which could mean one of two things. Either the batteries are weak or the formula doesn’t work for me and my MHR is actually higher. I just replaced the battery so I am keeping an eye on that. If it happens again then I’m going to get myself tested properly.

Once the MHR heart rate is determined, then specific heart rates (in terms of percentage) can be determined depending on what your target it. So when I write 75% MHR I’m actually saying my heart rate for that particular exercise was 75% of 180 which is 135 beats per minute. The heart rates between 60%-90% are further divided into 3 zones.

How do I determine what heart rate to train by. Each zones serves a specific purpose and I target specific zones and percentage for different purpose.

These are fairly easy to follow but what if you don’t have a Heart Rate Monitor? You can still use the concept and instead of relying on the monitor you rely on your perceived exertion. The easiest way is to check your ability to talk. You can compare maintaining a conversation easily while exercising and being completely unable to talk because you are out of breath.

Zone     Heart rate        Purpose                     Perceived exertion

Zone 1  60%-70%       Weight Control           Light easy conversation
Zone 2  70%-80%       Aerobic Fitness           Hard conversation
Zone 3  80%-90%       Performance                Heavy breathing. Conversation limited

At this moment I am spending a lot of time in Zone 1 and Zone 2 (and about 10% in Zone 3) because my current objective is building endurance which is the ability to sustain a certain level of physical exertion for long periods of time. When I did my half-marathon I averaged at 77% MHR and I was quite happy to have been able to sustain that for just under 4 hours. If I were to push to a higher rate I probably won’t last that long. My whole objective now is to gradually be able to run faster at the same heart rate. About 3 months ago my pace at 73% MHR was about 4 mins 30 secs per lap around the park near my house. Now I can go at 73% with a speed of just under 4 mins and that makes me happy.

I’ll start training more in Zone 3 once I am ready to tackle speed and pace work.

Hope that makes it easier (or has it made it harder?).

In a next article (don’t know when) I’m going to attempt to explain resting heart rate and its implications (I wrote the article ‘Matters of the Heart – Morning Resting Heart Rate RHR‘ eventually and you can view it the link)

 

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