Tuesday, September 11, 2012

Heart Rate Debate

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Recently, I've been experimenting with heart rate training.  Well, not really.  I've been wearing a heart rate monitor while I do my workouts, and reading about heart rate training intermittently.  So basically, I'm collecting data in anticipation of the day I might want to target my workout intensities based on heart rate.  Or maybe I'm analyzing my workout's efficacy (after the fact) based on heart rate data.

Why am I interested in heart rate?

Basically, I like the objectivity of it.  Targeting a workout toward a specific pace (or measuring it's success based on a certain pace goal) doesn't allow flexibility for varying temperatures, elevation, fatigue, etc.  Heart rate on the other hand increases with effort, no matter where that effort comes from (hills and heat increase your effort and hence increase your heart rate).  So in the extreme example of a hilly tempo run on a hot day, it might be near impossible for me to reach my goal pace (via the Mcmillan running pace calculator for example), but I can certainly reach my goal heart rate for a tempo run.

The real reason is that I use RunningAhead.com to log my runs, and I have to give each workout a name.  Often, I'm not sure if what I ran was hard enough to count as "Tempo", even though I'm fairly sure it was too hard for "Easy".  So what do I call these runs?  Nothing.  Right now they show up in my log as "Default".  This is what you call not training smart.  Fail.
"Default" is in third place for most miles of 2012!!  Really, I'm sure it's bigger than that, since I probably counted way too many as Tempo (blue) and Easy (green) than I should have.  Also, in case you're trying to add up my mileage for the year, I'll save you the trouble.  The answer is 953.2 miles as of 9/10/12.  
Of course it's not perfect.  Heart rate goals are only estimates geared toward specific workout goals (aerobic, lactate threshold, VO2 max, etc).  And there's also the fact that different sources list different heart rate ranges for each workout.  Oh, and there are even different ways to calculate a given % of your maximum heart rate.  Never mind the fact that the whole system is based off your maximum heart rate, and who knows if you've even got that right??

Here is my favorite example of conflicting information from different sources:
  • "70-80% of max HR is what I call quality junk miles.  It does you not much good, so stay out of this zone as much as you can." [Source]
  • "70-80% of max HR is the aerobic zone.  If you can’t run the soccer field like you used to, it is probably because you are not spending enough time in this zone. Training in the aerobic zone will improve cardiovascular fitness. Your body will more effectively transport oxygen-rich blood to your muscles. Your 30-mile road ride will begin to take less time. Your 10k’s will improve, etc.  [Source]
Umm, what???  You can't both be right.  Is 70%-80% the place to target or the place to completely avoid??  This is part of the reason I'm just collecting my own heart rate data first.  So I know what "feels right" to me, and so I can choose who to believe more intelligently.  I do have a feeling that those "Default" runs are probably "quality junk miles".  

So anyway, lets get to it shall we?  

Step 1 : Determine Your Maximum Heart Rate
There are a number of formulas that claim to be able to do this, but ultimately, you just need to go out and run hard and right down that number.  Here's how: 

1. Be sure you're well rested, well hydrated, and well warmed up.  You can conduct this test on a track or a moderately steep hill, which may work better if you're not an experienced track runner.  
2. Run hard and fast for 2 to 3 minutes. Jog back to your starting point. Repeat two more times, running a little harder and faster each time. On the third and last repeat, pretend you're running an Olympic race. 
3. Check your heart rate during and immediately after the last repeat. The highest number you see is your maximum heart rate (MHR).  (Source)

Alternatively, here are some formulas, using my age (A=28.9) as an example.  
  • 220 - A  = 191  (Classic)
  • 205.6 - 0.685 * A = 186   (Source) 
  • 208 - (0.7 * A) = 188  (Source)
  • 205 - (0.5 * A) =  191  (Source)
My "actual" max?  195.  I didn't do the "official" field test specified above, but wore my monitor during 800m repeats and hit 195 near the end of the last interval.  If I ever see a higher number on a workout, I'll take that as my max instead.  So yeah, none of the formulas predicted that.  

Step 2 - Calculate your Target Training Zones
Surely there is a straightforward formula for this right? Ha.  First, the HR range (as percentages) that you should target for different types of workouts (easy, tempo, intervals, races of different distances) vary slightly based on the source.  Second, if even if they all did miraculously agree that I should run at 65% for easy runs, there are multiple ways to calculate 65% of my maximum heart rate.  I put together a spreadsheet that calculates the target ranges of two common/reputable sources (McMillan and Runner's World) using two commen methods (Karvonen/reserve and "standard").  "Standard", is just a normal percentage calculation, using only your maximum heart rate.  So 65% of my MHR of 195 is 0.65*195=127.  The Karvonen method uses the concept of "heart rate reserve" and hence requires your resting heart rate (mine is 47, taken first thing in the morning before I get out of bed).  65% using this method is: (MHR-RHR)*X%+RHR, or for me at my example of 65%: (195-47)*0.65+47=143.  That's a pretty big difference.  Logically, heart rate reserve makes more sense to me.  65% of my maximum heart rate should be 65% of the available change capacity I have (195-47), not just a straight 65% of the maximum.  Think about it this way: if you are 80 years old, you're maximum heart rate might be around 140 bpm (220 minus age).  Your resting heart rate could be 95 bpm.  (Normal adult heart rates are 60-100bpm).  Using the "standard" percentage method to calculate 65% of this person's max would yield 91 bpm, which is BELOW their resting rate, and therefore impossible.  The Karvonen formula on the other hand, takes 65% of their available heart rate window, and yields a very reasonable 124 bpm.  All this to say, there is no way I'm ever going to run slow enough to get my heart rate down to 127, so I'm going with the Karvonen method.  ;)  Really, the two become more similar at higher percentages, it is only the easy/long/endurance ranges that are the issue.   

So that's my spreadsheet.  Want to use it yourself?  Just click here and then either "save a copy" (from the file menu) if you are a google docs user, or "download as ..." (also from the file menu) and choose Excel format.  Then just enter your resting heart rate and maximum heart rate to get your own target zones.  I added the "No Man's Land" bit at the end as an afterthought, after thinking about the quote at the beginning of this post about "quality junk miles".  I took no man's land as the area between the maximum of endurance/easy/long and the minimum of stamina/tempo from both the Mcmillan and Runner's World target ranges.  I'll tell you one thing:  I sure do see a lot of 160s on my heart rate monitor!  Oops.  I'll work on that I guess.  At least it's easy to remember.  Basically, I should never see 16x (except when ramping up or down of course).    

I guess now is the time to start looking at some of my heart rate data over the past few weeks to see where I've been falling, and if I've been naming my runs appropriately.  (I was going to put a table in here analyzing my workouts over the past few weeks, but it became tedious and was wordy and unclear anyway.)  Here is the upshot:  Most of my easy runs squeak in as easy at about 155bpm.  I am appropriately naming my "default" runs as default, because they are indeed in "no man's land" too fast for easy and too slow for tempo.  The only time I hit the target tempo and interval paces are when I run with a group.  I only have one long run from the past year with heart rate data (a 16 miler from 8/18) and the average heart rate for that was 158.  Just squeaked in under the max on that one.  (I have been afraid to wear my HR monitor for long runs and races, for fear of 1: chafing and 2: overanalyzing HR and pace data and ruining the run).   

There are a lot of numbers up there, and it's a lot to remember while I'm running.  McMillan + Karvonen yields the easiest to remember numbers, so going forward, here are my goals:  Easy and long runs less than 155 bpm.  Tempo/Stamina runs at least 170 bpm.  Intervals at least 180 bpm.  Simple.  :)

I learned a lot today.  Thanks for reading along.  (If you made this far!)  I guess I have some tough runs in my future, but hopefully you will see a faster Ty as a result!

3 comments:

  1. That's a lot of numbers.

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  2. nice analysis! but I think your link just goes to blogger.com, not to the spreadsheet. the whole maxHR thing is funny - I was once measured for real in a lab and all, and a few months later my watch said I exceeded it by a few bpm. I have doubts about the lab's methods ("oh, the mouthpiece doesn't fit? well, do the best you can") and my watch's accuracy (sometimes it thinks I'm at 220bpm, which I'm pretty sure I'm not), so the whole thing isn't specific, but I think it is still useful. Plus, "running to an HR target" is another game that makes actual running less boring.

    Also, I'm about 20 miles behind you for the year. :)

    ReplyDelete
    Replies
    1. Aww crap. I fixed the link. Thanks!

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