Follow your heart

I was recently asked how and why someone would use a heart rate monitor while working out. An in-depth answer to this question would fill a pamphlet – if not a book – and would include loads of mind-numbing jargon, formulas and definitions. I am going to try to answer these questions as simply as I know how. 

Why wear a heart rate monitor? Primarily a heart rate monitor is used to gauge and take control of the intensity at which you train.

We can physically sense the intensity differential between an easy jog and a heart-pumping sprint. But a heart rate monitor allows us to precisely observe (and even record for later study) the more subtle gradations of our bodies’ absorption of oxygen and excretion of carbon dioxide through the beating of our hearts.

Knowing what speed our hearts are pounding while we exercise allows us to actively choose what our workout is achieving…as well as grant us the ability to vary the intensity of our workouts. Monitoring the beating of your heart and comparing that number to percentages of your maximum heart rate (I’ll explain HRmax in a minute) lets you know exactly what the physical exertion level you are undertaking is achieving in your body.  

Different percentages of our maximum heart rate will yield different training objectives. There are many labels attached to these training ranges (also known as Target Heart Rates), but the following are a pretty good guide:

Warm up/Recovery/Easy – 50% to 60% of your HRmax

(Low risk of injury and good return on fat burn)

Aerobic Development/Fat burn/Endurance/Medium – 60% to 70% of your HRmax

(Increases body’s aerobic burning ability on a cellular level and most efficiently burns fat)

Aerobic Endurance/Cardio/Hard – 70% to 80% of your HR max

(Increases how long your body can train with sufficient levels of oxygen to burn glucose aerobically and not accumulate lactic acid)

Anaerobic endurance/Very Hard – 80% to 90% of your HRmax

(Increases how long your body can train at high levels without oxygen to burn glucose)

Speed/power/VO2Max/Extremely Hard – 90% – 100% of your HRmax

(Functioning at body’s maximum output, short in duration and helps to increase speed, power and volume of oxygen exchange)


If the goal of my workout is to increase speed, I will never do it with a heart rate meant for recovery and warm up. If the goal of my workout is to burn fat most efficiently, I won’t achieve it by working at 80% to 90% of my HRmax. You get the idea.

Testing for your HRmax can be like stepping through the looking glass into a world of acronyms and sadistic-seeming stress tests. But let’s forgo extreme HRmax accuracy for now and just get to a best-guess number that you can refine through use.

Take a quick trip online and search for “maximum heart rate calculator” or visit to calculate your HRmax and heartbeats per minute to match your target training zone. At this site, you will need to know your average resting heart rate. This is best measured over three days before you rise. Add the total beats per minute of all three days and divide the total by three. This is your average resting heart rate (RHR). Bear with me. Assessing your average resting heart rate is easy peasy compared to doing all the following calculations yourself. 

At the racedaynutrition site, type in your age, body weight, gender and average resting heart rate and hit the “Calculate” button. You will then be treated to a “personalized” chart displaying how many beats per minute your heart will make at each percentage of HRmax.

Here is where we get to the good stuff. Heart rate monitors do many things, personally I am still looking for the button on mine that makes breakfast. But the primary function of a heart rate monitor is to give you real time knowledge of how many times a minute your heart is beating.

Knowing how many beats per minute (BPM) your heart is making permits you to gauge what percentage of HRmax you are achieving. That sounds difficult, but it is easy. If I want to increase my aerobic endurance, I need to work at 70% to 80% of my HRmax. So, I follow the 70% to 80% lines across the grid to see the range of how many beats per minute my heart will be making at that level of exertion.  If I keep my BPM within that range I am training toward my goal. If my BPM fall or rise, I will move into a different training zone. By monitoring, I know which zone I am training in and I am free to control the intensity at which I am working to reach my training goals.

I must stress that these one-size-fits-all calculation results are great guidelines, but they are averages. The numbers they provide may be 100% spot on or they may miss the mark a bit. Olympic athletes in the same sport may vary by up to 60 beats per minute in their HRmax. Personally, I run about 10 to 20 BPM higher than my assessed HRmax depending on the calculation method.

To personalize your HRmax, you may search the web and explore the differing methods of testing HRmax by sport or you can customize the calculated HRmax by monitoring your body while working out.

Customizing is how I found my magic numbers. I ran with my heart rate monitor and after a long enough warm up to get all the systems functioning optimally, I started to see how fast I could run without hitting the wall. The best description I have for this sensation-wise, is the top speed at which I could run where I felt I could run all day with medium sustained effort. Once there, I looked at my heart rate monitor and remembered the number of beats per minute. Then I upped my running pace, watching the beats per minute until the effort became hard. At this new – more intense level – I felt like I could continue the pace, but it would be a slog. This told me I was breaking into the aerobic endurance training level. I did this testing over two weeks to assess my average beats per minute at each HRmax zone. Then I calculated my personal HRmax and my BPM at each target heart rate zone based on my real-time BPM.

Though these numbers can change a bit with your fitness level and age, they are awesome guides for really getting the desired intent out of each workout.

Beyond their primary function, heart rate monitors are also great for recording your effort at every second of your workout, corresponding to and even creating graphs that show exertion compared to terrain, distance and speed. You can upload your workouts and compare one to another to gauge your progress and analyze where you may need to up your game. I also never tire of using my heart rate monitor to gauge my recovery heart rate. After a speed drill or a tough workout, I love to see how quickly my beats per minute fall. The faster the fall, the more fit my heart is becoming. The faster my numbers drop, the more satisfied I am that I am doing the best I can do to make my life healthy and active.

A couple thoughts on heart rate monitors: If you decide you want to invest in a heart rate monitor, think about the likelihood you will continue to use this tool. I knew I would want long-term, reliable use, so I opted for a higher-end monitor with a chest strap (currently the most accurate heart rate monitoring method) rather than buying a less expensive model I would outgrow quickly. Also, many monitors actually let you know what zone you are in via a section of the monitor face. This is great if you don’t want to have to keep your numbers in your head. But it is best to know your real BPM numbers and program the watch to match your body rather than just accept the default settings. I love my Garmin, but Polar has been at the game the longest and has good base level watches under $100…and the Polar chest strap may be used with just about any cardio machine out there without the watch for use at your local gym.


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