Becoming a Better Animal:  How to Effectively Use Your Heart Rate Monitor.

Part 2 of 2       

by Scott Herrick 

 Welcome back!  Hopefully the information from Part I was a good overview of the possibilities and limitations of using your heart rate monitor (HRM) and I also hope you had a good sweat while collecting those maximums for cycling and running.   Here in Part II, we’ll put those numbers to use by presenting a couple options to use your HRM in workouts. 

Before We Talk Numbers…

 Many a manly man can tell by looking (while grunting) at their garage walls that no single tool is ever a complete solution, and your HRM is no exception.   Now that you’ve dropped a thousand drachmas on your new monitor to help tell you everything your ticker is doing during your bike ride, I’m here to tell you that there’s an even more overall effective and low-rent tool available—your own body.  

 While you may not be able to pinpoint your exact heart rate at any given time during a workout without using a monitor, knowing those triple digits is not the goal of your training sessions and races—it’s your overall intensity that’s important.  On Race Day, intensity correlates to speed over distance, which correlates to a finishing time.  Training sessions also have a goal of time and/or distance and intensity.  So far, no Olympic medals are given to the athlete who crosses the line with the lowest heart rate.  

 What we athletes are really looking for when using our HRMs is a simple number on a watch to give us a complete look under the hood at our body’s intensity.  What you will find in practice is that sometimes you will get an accurate intensity picture by looking at the readout and sometimes you can be fooled.

 During a constant pace run, many factors such as fitness level, weather, hydration, fatigue, soreness, time on the course, and stress all affect your heart rate even if you’re working at the same intensity on the same course as last week or last year.  Simply dialing in to a heart rate value during a training session or race can lead to under performing or early exhaustion just as easily as it can guide you to the correct pace to maintain.  However, if you know your body well enough, your HRM is still a very useful instrument on your dashboard.  

 I’ll present 2 methods of using heart rate data for your workouts. The first and simplest is using the percentage chart we created in Part I.  This chart is easy to follow but has some drawbacks in terms of accuracy.  The second method is using the HRM along with perceived exertion, or your own awareness of how intensely you are working.  Using perceived exertion takes some time to become aware of, but is more accurate in accounting for the realities of workouts such as changes in fitness, weather, hydration, stress, etc.

 Whichever method you choose to use in practice, your goal for using the monitor should be to become more aware of what your body is doing-- heart rate is only one indicator of your body’s intensity.  During all workouts you should try to become keenly aware of how hard you’re working and use heart rate as backup—not the other way around.

 Method One:  By The Numbers

The easiest method of using your HRM for workouts is to simply follow the numbers.  Let’s revisit the chart created back in Part I.  Chart I shows an example using my current heart rates based on the Karvonen formula. 

 Chart 1:  Heart rate chart based on Sport-specific Maximums and Resting Heart Rate 

 Planning workouts around these percentages is quite easy to apply.  Let’s put a name to some common workout ranges and then assign values:

 I.    Long Slow                        =  50-70%

II.  Endurance                        =  70-75%

III.  Steady State                   =  75-80%

IV. Tempo/Threshold             =  80-90%

V.  Interval                             =  90-95%

VI. Sprint/Power                     =  95-100%

 Your workouts could be planned using these ranges as:

Long Slow:      used for recovery, most runs off the bike, long easy workouts in the off season.

Endurance:     the bulk of your runs and rides.  You’ll still produce a sweat, but should be able to talk most of the time.

Steady State:   many training publications lately are recommending to not spend much time in this zone.  It has been recommended to either drop back to the easier zones or move up.  In the past I haven’t tried to avoid this area, so I can’t yet advise to follow this information.  My personal training in the next year is aimed at experimenting with this to find out.

Tempo/Threshold:  fast work that you can hold for some number of minutes.  Similar to an average (not max!) pace you can hold for a 10k length race.  Typical workouts in this zone include tempo work with a slow warm up and warm down and a 15-30 minute effort in the middle at this high pace.

Interval: short bouts of 1-5 minutes at high pace, similar to end of 5k race.  These workouts may be performed but are not the staple of basic endurance training.

Sprint:  All out efforts usually saved for races.  This pace can only be held for less than a couple minutes at most.

 In general, the bulk of your workouts will be geared around Endurance and Tempo/Threshold.  Higher intensities are also used for swimming since recovery time is quite short.  Planning a week or even an entire season becomes more complex since each individual has a different goal set and also different strengths and weaknesses.  Whether you work with a coach or find training plans on the net or in books, you can easily translate these effort levels into the plan descriptions. 

 While planning simplicity is an advantage, one major drawback to using this chart is a change in fitness levels.  Starting out as an endurance athlete or even starting out the new season, fitness levels are probably not going to be at a peak.  If you set out to do an easy long run at 70% by following the monitor, this pace might be just fine when beginning as an endurance athlete or even beginning a new season as an experienced athlete.  However, 9 months later when fitness has improved considerably the pace might be much too slow even at 70%.   This drawback of following fixed percentages leads us to Method Two…. 

Method Two:  Gettin’ in Touch With Your Feelings

Long before endurance athletes were sitting around a pint bragging about their HRM graphs of everything from snogging to running up Pike’s Peak, a Swede named Dr. Gunnar Borg was publishing research on measuring the physical and mental sensations that people experience. 

 Dr. Borg devised scales to capture things like pain, taste, brightness, noise, and even moods.   You have probably already seen one of his scales hanging up at the gym—the Rating of Perceived Exertion (RPE).   The RPE scale was intended to subjectively put a concrete value to the amount of workload people experienced during physical exertion. 

 Below in Chart 2 is Borg’s Modified RPE chart showing exertion rates.  The chart is numbered from 0 to 10 (with a peak category called “*” or off the chart).  Borg wrote simple descriptions for each level ranging from complete rest at 0 to maximal possible exertion at “*”

The original RPE scale is numbered from 6 to 20, with 6 being complete rest and 20 representing complete exhaustion.  The reason for this odd numbering is that the subjects of Borg’s exertion study were all fit individuals who had heart rates that roughly corresponded to 60 at rest and a maximum for his tests of around 200.  Borg later created the Modified RPE scale that is numbered with a more convenient 0 to 10 range.  We’ll use this one.   I’ve put both together here in the same listing in case you are already familiar with using the original RPE values. (1)  

Chart 2:  Borg’s RPE and Modified RPE Chart

Applying The Heart Rate Numbers--Your Personal RPE Chart

Also from your data in Part I, we can now begin to match some hard numbers with these RPE levels.   Just as your resting and maximal values are unique to you, your chart data will be as well.  I’ve created a couple RPE charts here that you can print out to use. 

 Chart 3 is a full page with RPE values and places to enter your current personal heart rate data.  At the end of this article, I’ve also included a Chart 4 below which is a much smaller version that you can tape onto your bike stem or tape to back of your mp3 player to take along during workouts.

To fill in the chart, you’ll see that 0 indicates total rest—here you can enter your resting heart rate (RHR).  At level “*” (or off the chart), enter your cycling and running maximum heart rates (MHR).  In addition to Borg’s descriptions, I’ve added some more that should help.

 Chart 3:  Matching Heart Rates with Borg’s Modified RPE scale

Now comes the hard part—filling in the middle of the chart.  The easiest way to do this is practice.  Wear your monitor on bike rides and runs of all different intensities and get a feel for how hard you’re working and try to make an honest assessment placing an level number to that effort.  While it would be much easier to calculate a fixed number but the values wouldn’t be accurate.  Also, most of the values for expending effort take up most of the range  of the chart so drawing a line between resting and maximal will not give accurate numbers.(2) The reason is that there are only a couple levels to describe everything from complete rest to fast walking is that most of us don’t have much of an interest in distinguishing effort levels from just watching TV to dialing the pizza guy while watching TV (although I’m sure the calorie burning does add up after enough dialing.)

 So why isn’t there a formula to fill in the chart and why use it instead of the simple chart from Part I?  Matching effort level to heart rate is very closely linked to your fitness level at a specific time in each sport .  For example, in January, running at what feels like a moderate pace (Level 3) might show as 150.   In June, that same moderate feeling run may only show as 140 due to many factors such as increased fitness and warmer temperatures, or even negative factors such as overtraining or illness.   If you had stuck to running January’s 150 level for your run, you’d be going too hard for your moderately scheduled workout.   

 A good way to practice using the chart is to spend some workout time playing a game of Heart Rate Jeopardy:  “I am working fairly strong.”….”What is 155?”   It sounds cheesy (and it is) but you’ll be surprised after a few weeks of how close you can come to the actual reading.  Also take your HRM to races and see how good you are at guessing.  Race stress and increased pace from your normal training sessions might keep you out of the Final Jeopardy round for a while until you become more tuned in to your body, but practice, practice, practice.   A final note about race heart rates…you might not be able to use your normal training values on race day due to increased stress and adrenalin.  Using your training rates in a race situation can leave you going at a lower pace than your body is capable of for a given intensity due to “race stress.”  Again, know your own body—if you don’t feel any stress and it feels like a calm day on the course you can trust the monitor a little more than if you’ve got cyclists zooming all around you with friends and family cheering roadside.   

Chart 4:  Compact RPE/Heart Rate Chart

(print one each for the bike and run)

Myth:  The Fat Burning Range

Back in Part I, I presented a few myths regarding heart-rate monitors and heart rate based training.  Now before departing, there’s one more that I’d like to talk about:  fat burning range.  In quite a few magazines and web sites I’ve seen articles that show where working out at a lower intensity will burn more fat thus leading to an even slimmer, trimmer you.   While burning more calories will get you into those smaller jeans, doing so by working out at a lower intensity is not the fastest way.  In order to lose weight, you need to create a calorie deficit—it doesn’t matter where that deficit comes from. 

It is true that while performing aerobic exercise that at the lower end of the aerobic zone (about Level 3 on the Modified RPE chart) that the body does burn a higher percentage of fat than carbohydrate and that at higher intensities (Level 8) the body burns a higher percentage of carbohydrate than fat as fuel.(3) 

Notice that I said percentages and not total calories.  A Level 8 workout for 30 minutes is going to burn far more calories than at Level 3.  Let’s look at an example of a 150lb person running at Level 3 (ex: 12min pace) and also running at Level 8 (7.5min pace): 

Level 3 run for 30 minutes:  burn 55% fat, 45% carbohydrate, 288 total calories

Level 8 run for 30 minutes:  burn 10% fat, 90% carbohydrate, 460 total calories

 Even though the Level 8 workout may have burned less overall calories from fat, the overall number of calories is much higher.     More total calories burned = Smaller Jeans.

Final Note:  Cardiac Drift

Now that you have a good overview of RPE and using your monitor in workouts, I’d like to another point that can cause some discrepancies between effort level and heart rate.  During long workouts of usually more than 1 hour, the heart has a tendency to beat slightly faster even though you do not feel as if you are working any harder—this is called cardiac drift, or cardiac creep.  The heart rate increases even for the same effort expended because as you sweat, your blood volume decreases due to fluid loss and also your heart tries to do its part in regulating body temperature.  The good thing for you is that in most cases you might not need to slow down as the heart rate creeps up.  As long as your major muscle groups aren’t being affected and you don’t feel more laboured, there’s no reason to strictly obey your HRM.  Common sense should prevail in extreme conditions of heat, cold and dehydration though.  If you’re training or racing and your HRM is showing elevated (or depressed in the case of cold temps) values, do a self assessment to see if you really should follow the numbers or if common sense tells you to slow down.  Again, the point of this entire article is to show that the HRM is a useful tool, but that it doesn’t tell you everything you need to know. 

 Thanks for reading and feel free to drop me a mail if you have questions or have had some interesting results using your monitor.

 Scott

 herrick_scott@hotmail.com

 References

1.      Sport Nutrtion for Health and Performance.  Manore and Thompson.  Human Kinetics.

2.    For you numbers geeks, the original RPE chart, numbered 6-20 has a much more linear relationship to heart rate and VO2max than the modified chart.

3.     A Comparison Between Two Rating Scales For Perceived Exertion.  Borg, Elisabet.  Department of Psychology, Stockholm University, Sweden.

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