Understanding Heart Rate

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Many people take resting and exercise heart rates, either with a heart rate monitor or by feeling their pulse. Your resting heart rate provides information about stress and overtraining levels, while your exercise heart rate provides a good estimate of exercise intensity. Both of these variables may change over time if you continue to exercise, and provide good markers of physical conditioning.

Resting Heart Rate

Take your resting heart rate at your most relaxed. For most people this will be lying in bed, either before falling asleep at night, or first thing in the morning. But not after a loud alarm clock! Find your pulse, and count for thirty seconds, then multiply by 2 to get your beats per minute (bpm).

Your resting heart rate will vary somewhat from day to day. This is normal, and over time you will get a sense of what a normal range is for you. In general, resting heart rates tend to range from 60 to 80 bpm. Some people have resting heart rates higher than this, while athletes may have resting heart rates as low as 40 bpm or less.

Many factors affects your resting heart rate. Anything that stimulates the fight-or-flight stress response will speed up your heart rate, including emotions such as anxiety, stress, and excitement. Drugs such as nicotine, caffeine, pseudoephedrine, and ephedra do the same thing. Fever, illness, overtraining, and large meals also elevate resting heart rate.

If you have not been exercising regularly, you may see a slight decrease (5 to 10 bpm) in your resting heart rate after a few months of training. This is a healthy sign that means your nervous system is, well, less nervous and more balanced. You may find you are also feeling a little less irritable and anxious.

Exercise Heart Rate

The harder you are exercising, the more blood you must circulate to deliver nutrients and oxygen, and to remove heat and waste products. This is why your heart rate increases in proportion to exercise intensity. Taking heart rate during exercise tells you how hard you are working.

Your health providers or exercise instructors may have recommended certain target heart rates for your exercise program. They want to be sure you are working hard enough to get all the wonderful health benefits possible from your exercise program. If you have health problems, you may have been told to keep your heart rate below a certain level to be sure you are exercising safely.

Target heart rate zones may have been calculated from an exercise test that measured your heart rate during exercise. The test may or may not have measured your maximum heart rate. (Maximum heart rate is taken while you exercise at maximal effort.) The test may have linked your heart rate to your perception of exertion, how hard the work felt to you. Target heart rates based on exercise testing tend to be the most helpful.

Target heart rate zones calculated from age-predicted maximum heart rate estimates may not be as accurate for you. Predictions of maximal heart rate have a standard deviation of ten beats per minute. This means that at least a third of all exercisers will have hears rates higher or lower than a twenty beat range around the maximum heart rate predicted for their age. While your age-predicted maximum heart rate might be 170 bpm, only two thirds of exercisers your age will have a true maximum heart rate of 160 to 180 bpm.

As you work with target heart rate zones, you will become accustomed to what certain target ranges feel like. If you have to work like a maniac to get your heart rate high enough to reach your recommended zone, talk to your exercise instructor. Maybe you have a naturally lower heart rate. Similarly, if our heart rate always seems very high even with a fairly light workload, you may have a somewhat higher than average heart rate.

With regular exercise training, you may find that your exercise heart rate for a standard workload (for example, running on the treadmill at 8 mph) decreases. This is a sign that your body is getting better at producing energy. In order to exercise in your target zone, you will need to increase the exercise intensity.

 

Barbara A. Brehm, Healthy Learning