Heart Rate during Exercise

A client recently asked me what her heart rate should be during her cardio. Wow, great question and one I get asked a lot. The short answer is: it depends.

The long answer to my client's question depends on her exercise goals, her age, her present fitness level, what medications if any she's taking and whether she or her family have any history of cardiovascular disease, diabetes, strokes or thyroid problems.

The best person to answer her question is her MD. Besides "it depends" and "ask your doctor", I can offer her two things: the following formula: 220-her age x the level of exertion desired and my recommendation for a fabulous tool (no, not a hammer!).

Many cardio machines have charts giving ranges of heart rates for 65% and 85% exertion depending on age. 65% represents moderate intensity exercise; 85% represents vigorous exercise. Ok, that's easy-no math.

But let's take the formula for a test-drive using the following example:

Joanie is 40 years old, apparently healthy with no family history of cardiovascular issues. She takes no medications and doesn't smoke. She's reasonably fit and has a small weight loss goal of 10 lbs. She's been walking 5 days a week about 3 miles a day for the past 6 months but hasn't lost the weight she wants. The formula is 220-40 x .65 or .85 therefore her heart rate range for 65%-85% intensity is 117-153 measured in BPM (beats per minute).

After her warm-up, Joanie watches her heart rate using the machine's heart rate monitor and attempts to keep it between 117-153. If she wants to keep her exercising to moderate intensity, the formula says her HR should be 117 BPM, to exercise at vigorous intensity, HR at 153 BPM.

That seems simple enough. However Joanie is not the mythical average human being and other factors contribute to what her heart rate numbers might be such as her genetic make-up, the type of cardio machine she is using, her fitness level, etc. She will have a slightly different heart rate response in terms of actual numbers if she's running or biking or using a cross trainer machine. Genetically maybe she has a slower heart rate than average or possibly a higher heart rate than average. If she's deconditioned or extremely conditioned, her fitness level will affect
what her heart rate is. Finally the machines are not always 100% accurate.

There are more complications: the formula was originally derived from research done on middle-aged men with cardiovascular disease! Women, young people or middle-aged men without cardiovascular disease won't get an completely accurate heart rate for themselves.
Oh dear.

Another problem: the starting point for the formula 220 is what is postulated for average heart rate for a newborn. Average means some newborns have higher heart rates than 220, some have lower. Hmmm, how do you know if you were an average newborn or not?
Oh my.

The formula has been around for quite awhile. Many folks interested in their health and fitness have run across it at some point or another. It's an ok starting place but not necessarily the most reliable guide for you.

My recommendation (besides it depends and ask your MD) is to buy a heart rate monitor and start observing your heart rate over time and under a variety of exercise situations.

Many brands exist. I own a Polar F-6 and I'm happy with it. Using a heart rate monitor has given me a great deal of information about my fitness level, the response of my cardiovascular system as well as which cardio machines and programs still kick my butt. Hint: it's not the treadmill and it's not quick-start.

By using a heart rate monitor, over time you will begin to see your own particular patterns. By tracking this information, you will be able to correlate your RPE (rate of perceived exertion)
with a range of heart rates. For me, on the Step-Mill, if my heart rate is 140-150, I'm working pretty darn vigorously, corresponding to an RPE of level 8-9. Sprints on the elliptical translate into approximately 130-145 BPM, still a RPE of 8-9 for me. Walking on the treadmill at 5% incline barely gets my heart rate above 100 BPM, an RPE of 2-3 for me.

As you can see, this subject is substantial with a lot of factors contributing to the answer.

OK, here's your quiz: which of the following is/are the correct answer(s) to the question "What should my heart rate be during exercise?"

Answer A: ask your MD
Answer B: it depends
Answer C: 220-your age x .65 or .85
Answer D: determine using a heart rate monitor
Answer E: Use RPE-rate of perceived exertion
Answer F: zero, 0, nothing, nada, zilch
(I just threw this one in to see if you were still awake)
Answer G: all of the above with the exception of Answer F.

Good luck!

In Health,

Laura