Overexerting yourself

Beware of pushing yourself too hard too often. If you're short of breath, in pain or can't work out as long as you'd planned, your exercise intensity is probably higher than your fitness level allows. Back off a bit and build intensity gradually.

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 subtract your age from 220. 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 minute during exercise.

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.

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

  • 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, aim for the lower end of your target zone (50 percent). Then, gradually build up the intensity. If you're healthy and want a vigorous intensity, opt for the higher end of the zone.

How to determine your target zone

Use an online calculator to determine your desired target heart rate zone. Or, here's a simple way 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.
  • Calculate your resting heart rate by counting your heart beats per minute when you are at rest, such as first thing in the morning. It's usually somewhere between 60 and 100 beats per minute for the average adult.
  • Calculate your heart rate reserve (HRR) by subtracting your resting heart rate from your maximum heart rate.
  • Multiply your HRR by 0.7 (70 percent). Add your resting heart rate to this number.
  • Multiply your HRR by 0.85 (85 percent). Add your resting heart rate to this number.
  • These two numbers are your training zone heart rate. Your heart rate during exercise should be between these two numbers.

For example, say your age is 45 and you want to figure out your target training heart rate zone. Subtract 45 from 220 to get 175 — this is your maximum heart rate. Next, calculate your HRR by subtracting your resting heart rate of 80 beats per minute from 175. Your HRR is 95. Multiply 95 by .7 to get 66.5, then add your resting heart rate of 80 to get 146.5. Now multiply 95 by .85 to get 80.75, then add your resting heart rate of 80 to get 160.75. So your target for your training zone heart rate should be between 146.5 and 160.75 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:

  • Stop momentarily.
  • 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.
  • 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, including some medications to lower blood pressure, 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.

Interestingly, research shows that interval training, which includes short bouts (around 15 to 60 seconds) of higher intensity (maximal effort) exercise alternated with longer, less strenuous exercise throughout your workout, is well-tolerated. It's even safe for those with certain cardiac conditions. This type of training is also very effective at increasing your cardiovascular fitness and promoting weight loss.

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.

Sept. 03, 2016 See more In-depth