continued:

Exercise intensity: Why it matters, how it's measured

Gauging intensity using your heart rate

Another way to gauge your exercise intensity is to see how hard your heart is beating during physical activity. To use this method, you first have to figure out your maximum heart rate — the upper limit of what your cardiovascular system can handle during physical activity.

The basic way to calculate your maximum heart rate is to take 220 minus your age. For example, if you're 45 years old, subtract 45 from 220, to get a maximum heart rate of 175. This is the maximum number of times your heart should beat per a minute while you're exercising.

Once you know your maximum heart rate, you can calculate your desired target heart rate zone — the level at which your heart is being exercised and conditioned but not overworked. Working out within your target heart rate zone gives you the best results for burning fat and losing weight. If you work out below that zone, you reduce your exercise intensity, and you may not burn as many calories. If you work out above that zone, you may not be able to work out as long as you planned.

Here's how heart rate matches up with exercise intensity levels:

  • Light exercise intensity: 40 to 50 percent of your maximum heart rate
  • Moderate exercise intensity: 50 to 70 percent of your maximum heart rate
  • Vigorous exercise intensity: 70 to 85 percent of your maximum heart rate

If you're not fit or you're just beginning an exercise program, opt for light exercise intensity and gradually build up to a higher intensity. If you're healthy and want a vigorous intensity, opt for the higher end of the zone.

To determine your desired target heart rate zone, use an online target heart rate calculator, which does the calculations for you. Or, here's how to do the math yourself. If you're aiming for a target heart rate of 70 to 85 percent, which is in the vigorous range, you would calculate it like this:

  • Subtract your age from 220 to get your maximum heart rate.
  • Multiple that number by 0.7 (70 percent) to determine the lower end of your target heart rate zone.
  • Multiply your maximum heart rate by 0.85 (85 percent) to determine the upper end of your target heart rate zone.

For example, say your age is 45 and you want to figure out your target heart rate zone for vigorous intensity exercise. Subtract 45 from 220 to get 175 — this is your maximum heart rate. To get the lower end of your target zone, multiply 175 by 0.7 to get 123. To get the higher end, multiply 175 by 0.85 to get 149. So your target heart rate zone for vigorous exercise intensity is 123 to 149 beats per minute.

How to tell if you're in the zone

So how do you know if you're in your target heart rate zone? Use these steps to check your heart rate during exercise:

  1. Stop momentarily.
  2. Take your pulse for 15 seconds. To check your pulse over your carotid artery, place your index and third fingers on your neck to the side of your windpipe. To check your pulse at your wrist, place two fingers between the bone and the tendon over your radial artery — which is located on the thumb side of your wrist.
  3. Multiply this number by 4 to calculate your beats per minute.

Here's an example: You stop exercising and take your pulse for 15 seconds, getting 33 beats. Multiply 33 by 4, to get 132. If you're 45 years old, this puts you in the middle of your target heart rate zone for vigorous exercise, since that zone is 123 to 149 beats per minute. If you're under or over your target heart rate zone, adjust your exercise intensity.

Target heart rate tips

It's important to note that maximum heart rate is just a guide. You may have a higher or lower maximum heart rate, sometimes by as much as 15 to 20 beats per minute. If you want a more definitive range, consider discussing your target heart rate zone with an exercise physiologist or a personal trainer. Generally only elite athletes are concerned about this level of precision. They may also use slightly different calculations that take into account gender differences in target heart rate zones. These differences are so small that most casual athletes don't need separate calculations for men and women.

Also note that several types of medications can lower your maximum heart rate and, therefore, lower your target heart rate zone. Ask your doctor if you need to use a lower target heart rate zone because of any medications you take or medical conditions you have.

Reap the rewards of exercise intensity

You'll get the most from your workouts if you're exercising at the proper exercise intensity for your health and fitness goals. If you're not feeling any exertion or your heart rate is too low, pick up the pace. If you're worried that you're pushing yourself too hard or your heart rate is too high, back off a bit.

If you have any medical conditions, you're not sure what your exercise intensity should be or you want help determining your target heart rate zone, talk to your doctor or consult a professional exercise specialist.

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References
  1. 2008 physical activity guidelines for Americans. U.S. Department of Health and Human Services. http://www.health.gov/paguidelines/pdf/paguide.pdf. Accessed Jan. 17, 2011.
  2. Target heart rates. American Heart Association. http://www.americanheart.org/presenter.jhtml?identifier=4736. Accessed Feb. 7, 2011.
  3. Stay active and be fit! President's Council on Physical Fitness and Sports. http://www.fitness.gov/publications/council/stayactiveandbefit_pdf.pdf. Accessed Feb. 7, 2011.
  4. Laskowski ER (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 16, 2011.
SM00113 March 5, 2011

© 1998-2013 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.

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