Saturday, November 13, 2010

Heart Beats Per Mile Run

Most people have heard of tracking the average heart rate during a run.  Same with average pace of the run.  Distance is almost always tracked along with time.  How about a new statistic--average heart beats per mile run? I heard about this several years ago on the ULTRA listserv and tried it out for a few months.  It was interesting seeing what paces led to the most efficient heart rate (beats per mile).  Run fast and you'll cover a lot of ground in a given amount of time...but your heart rate will be very fast.  Run slow and you'll keep that heart rate low, but cover much less ground.  The key for efficient running is to find your sweet spot--what is your most efficient pace where you cover the miles and keep your heart rate under control.  In a car, you might think of your best miles per gallon speed.  What is your best "beats per mile" for running?

If you wear a heart rate monitor that provides average heart rate for your entire run, then simply take that number (for instance, 130 beats/minute) and multiply it by the total minutes run (let's use 45 minutes for this example) and then divide by miles run (5 miles for this example):

130 beats/minute x 45 minutes / 5 miles =  1170 beats/mile

Once you start tracking heart beats/mile, you'll focus on staying relaxed and efficient.  Maybe faster isn't better.  Slow might not be efficient either.  Find that middle ground that is your most efficient pace by tracking heart beats per mile.  Try and beat the system by walking?  Sure, you'll have a very low average heart rate, but it'll take a lot of minutes for each mile. Experiment and see for yourself.  And the speedsters out there won't beat the system by sprinting that mile or two...minutes will be reduced, but heart rate will be extremely elevated.  So go out and run with a group of friends, track your beats/mile, and see who can get the lowest result.  It's a statistic that can be used to compare the efficiency of runners even when one is running faster or slower, shorter or longer...pretty cool, eh?

15 comments:

Anonymous said...

Isn't this a linear function?
Look at the table and you will see what I mean. http://de.wikipedia.org/wiki/Conconi-Test (The English page is text only)
And above the aerobic threshold, you are far more "efficient" (in bp distance), because you run faster but the bpm stay nearly the same. For example, I ran 165bpm-13km/h, 170-14, 175-15, and then 180-18, 185bpm-25+km/h

Chris said...

Excellent point.

Joe W. said...

I've been thibnking about this metric independently lately, and I think it is a good tracker for personal long-term cardiovascular performance. As for the anaerobic rolloff, if you've ever tried to run 30 mins or more purely in the anaerobic zone, you'll know it is both difficult and potentially damaging. You might be able to see brief gains in beats/mile by running anaerobically in spurts, but if you're measuring this statistic over 5+ mile runs and averaging it for the whole run to compare to other runs, then the anaerobic effect should not play a big part.

Chris said...

Joe,

I keep thinking about it too. I agree with you about the anaerobic zone not being a good preference for maximizing the beats/mile. I also think you are on target about using this metric as a good longitudinal measuring stick for improvement. Lately I have been getting fairly good runs in with very low HRs. I couldn't do that 1 year ago.

Benjamin Frey said...

I stumbled onto the same idea recently. I have been tracking my heart rate as I run for a few months and I think the beats/mile concept is a decent measure of progress. For instance, I have been trying to keep my heart rate at around 155 and adjusting my pace to do so on my daily 5k runs. I have been running more or less the same route and I have noticed that my pace has been improving (incrementally, but almost each time I run it improves) but I had difficulty confirming the improvement since I had small variations in my heart rate each time. Having the same idea as you, I multiplied my pace by my heart rate and graphed it over time and what I have seen is a distinct and almost continuous decline in the beats per mile. It's true, as has been pointed out, that the figure itself is a linear function of the pace for a given person at a given time. However, as one's aerobic performance improves over time, one can use the beats per mile as a way of tracking that improvement. In order to track the improvements, You could track the improvements by looking at past runs at the same pace and noting a drop in heart rate, but the beats per mile figure has the advantage of allowing one to compare somewhat different paces and heart rates on a single standard.

Chris said...

Glad you've seen this concept useful for measuring progress in your running.

sclim said...

It wasn't clear to me if the fact that at resting HR the velocity is zero. What you are trying to get is the slope of the line of HR vs speed in mph. Have you factored in the resting HR and zero mph coordinate?

Also, did your HR stay the same for a given speed, or did it tend to rise as the distance increased? It tends to do this for me.

Chris Ⓥ said...

@sclim

No, I am not trying to graph the HR vs velocity (so i do not have a zero start point). Just tracking HR beats/mile and seeing what is most efficient and how it becomes more effient with betetr fitness. My HR does trend upward at same speed as the distance gets longer. I suppose this is cardiac drift due to fatigue, dehyration, and higher core body temperature.

sclim said...

OK, got you. This would mean that your Heart Beats per mile would differ at different speeds. For instance, if your hear rate at rest was 60, then at 0 speed, your heart rate would be 60, so you would have infinity beat per mile.

You could correct for this by subtracting the value of your resting heart beats (60 per minute) from your running time. Then you would be getting, in effect, your Reserve Hear Beats per mile, and this would be a more stable value. I am making this up as I go along, but I am influenced by the concept of Karvonen's Heart Rate Reserve, which is the portion of the heart rate range that is affected by exertion, running etc.,in a more or less linear correlation, that is the range from the resting heart rate to the maximum hear rate (calculated by HRR = HR minus resting HR).

I guess you could also correct for the HR drift with duration, but that would make it even more complicated!

sclim said...

Whoops, I just went for a run and thought it over -- I picked a wrong point to derive a slope!! Dividing by zero is always a bad idea! My last calculus class was 50 years ago!!

So, going back to basics and comparing to a very low speed above zero:


If I run at 12 km/h (= 0.2km/min), my HR levels out at 140 HB/min

Therefore by your formula my HB/km is 140/0.2 HB/km = 700 HB/km (at 12 km/h)

If I run/walk very slowly, say 1.2 km/h (0.02km/min), my HR goes to about 62 HB/min

Therefore by your formula my HB/km is 62/0.02 HB/km = 3100 HB/km (at 1.2 km/h)

This large variance has less to do with changing efficiency at very low speed than an artefact driven by the fact that even at 0 speed, the HR is not at zero but at a positive number which is the resting HR. In my case this number is 52 HB/min

If we use Reserve HR instead of raw HR:

at 12 km/h (0.2 km/min) my Reserve HR is 140-52 = 88 RHB/min, and my RHB/km = 88/0.2 RHB/km = 440 RHB/km.

at 1.2 km/h (0.02 km/min) my Reserve HR is 62-52 = 10 RHB/min, and my RHB/km = 10/0.02 RHB/km = 500 RHB/km.

The variance here, even at this ridiculous low speed is much less, and when calculated for realistic running speeds should give a much more appropriate and uniform measure of efficiency, don't you think?




Chris Ⓥ said...

You are getting into this a lot more than even me! Good data and thinking. I always liked HRR rather than basic HR or %maxHR.

sclim said...

Well, you're the one that started it LOL!!

Seriously, I have been running consistently for 16 years, but only seriously thought about actual Heart Rate Reserve numbers for the past year, even though I had read about Karvonen's HRR long ago and knew the general idea. It has always annoyed me basing prescribed running pace/intensity in drills (I am a great fan of Jack Daniels Running Method) based on percentage of Max HR because of the inability to easily extrapolate backwards and get a corresponding percentage of max speed, but I never got round to it.

Finally this past year I bit the bullet and constructed and memorised a chart for my own percentage HRR and now know what the HR should be for my 50% 55% 60% 65% 70% 75% 80% 85% 90% and 95% HRR. Fortunately for me, by an accident of fate, these numbers happen to be whole numbers and easily calculated in my head.

Your innovation was very intriguing, and my own recent intellectual exercise made it logical to tweak your idea a bit, which is what I did. My problem was that I didn't know what to call the unit. A Reserve Heart Beat is really the same as any Heart Beat, except that as a group they are all the heart beats that line up above the Resting Heart Beat mark. Calling it a special name Reserve Heart Beat seems to honour it more than it deserves, but the whole reserve computation needs to be distinguished from the plain old Heart Beats per km value, so that's why I ended up with the clumsy Reserve Heart Beats per km monicker.

Chris Ⓥ said...

Works for me..."Reserve Heart Beats/Mile" (or km).

Iain Denby said...

My goodness -there ARE other Geeks out there!

Been doing the same and notice that for me, the faster my pace the lower the heart beats per mile are.

Is this something you'd expect for everyone?

Chris Ⓥ said...

Iain,

Not sure if this is true for everyone, but I think a moderately fast paced run will be more efficient than a really slow one (or a really hard one).