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Is my target heart rate calculation accurate?

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Updated June 21, 2014

Running on treadmill
Paige Waehner
Question: Is my target heart rate calculation accurate?
Answer: The short answer to this question is: Probably not, something you already know if you’ve used a target heart rate calculator only to realize you’re barely breaking a sweat during your workouts.

The accuracy of your target heart rate zone depends on the calculation you’re using. Most target heart rate calculators use an age-predicted maximum heart rate (MHR). You take a percentage of that MHR, usually 60% at the low end and 90% at the high end, to come up with your heart rate training zone.

The problem is the equation itself, 220 - age=MHR. Scientists have figured out that the validity of this equation has never been established and that it usually underestimates how hard you should be working.

Recent studies have found that a more accurate formula is 206.9 - (0.67 x age)=MHR, but even this may vary by up to 10-20 beats per minute higher or lower. If these formulas are so far off, how do you find your real target heart rate zone?

Finding Your Own Heart Rate Zones

The only way to get a true measure of your MHR is to take a stress test, something your doctor may recommend if you have heart problems. For the average, healthy exerciser, getting a stress test (which can cost more than $200) probably isn’t an option.

Formulas and calculators can be useful to a certain degree, but no formula will be 100% accurate. Don’t be a slave to those numbers but, instead, use them as a starting point for finding your own training zone. You can do that by using a combination of your heart rate and your perceived exertion, a scale of 1-10 for how hard you feel you’re working. Below is an example of how you can use these tools together to create your own heart rate zone:

  1. Warm up at your usual pace and make a note of your heart rate. Match that to a number on the perceived exertion scale – for most warm ups, this is around level 4
  2. Increase your pace until you’re working at a moderate pace, about level 5-6, and make a note of your heart rate.
  3. Continue through the different perceived exertion levels, 6-7, 7-8 and 8-9. You can do this by going faster, adding incline and/or adding resistance. Make a note of your heart rate at each level.
  4. Come up with your own heart rate range by using your level 5-6 heart rate, which is the low end of your range, and your level 8-9 heart rate, which is the high end of your range.
  5. Adjust these numbers as you go through different workouts and get a feel for how hard you're working at different heart rates.

To see how this works, below is a chart of heart rate zones I created for myself over the past few years. Keep in mind that this is just an example and these numbers fit my own age, fitness level and what feels right for me. Your numbers may be higher or lower depending on your own circumstances:

  • Level 4, warm up heart rate range: 135-145 bpm
  • Level 5, moderate heart rate range: 145-150 bpm
  • Level 6-7, moderate-hard heart rate range: 150-160 bpm
  • Level 8, hard heart rate range: 160-165 bpm
  • Level 9, killer heart rate range: 165-175 bpm

More About Target Heart Rate

Source:

Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001 Jan;37(1):153-6.

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