The human heart can beat only 220 times per minute, and that maximum can only be attained by a young child. The maximum number of times your heart can beat declines with age for reasons that are not clearly understood. The decrease in the number of beats per minute with age has nothing to do with stamina or fitness. Marathon runners often peak in their late 30s despite their hearts beating less times per minute than a 10-year-old or a 20-year-old.
If you want to determine your maximum heart rate, or the maximum number of times your heart can beat per minute, subtract your age from 220. Say, for example, you are 40 years old. Subtracting 40 from 220 leaves 180, the maximum number of heart beats per minute for a 40-year-old.
Your maximum heart rate helps you determine what sort of a workout is best for you from an aerobic standpoint. If people were to push their heart rate to the maximum for their age, they would quickly tire and have to stop and rest. Many believe that the ideal maximum heart rate for a workout should be about 80 percent of the maximum for your age. In other words, multiply your maximum heart rate by .80 and you'll get the ideal heart rate for a workout, also known as your target maximum heart rate. So for the aforementioned 40-year-old, his target maximum heart rate would be 144 beats per minute, or 180 x .80.
If this 40-year-old were doing a serious workout -- such as running at a good pace -- he might want to hover around 144 beats per minute for much of the workout and slowing down or speeding up as needed.
However, many people prefer workouts that are not this intense but still effective. They might want to target 60-70 percent of the maximum beats for their age as an ideal number. Still others like to vary their workout intensity from day to day or even within the same workout, such as walking a bit, then jogging a bit, then walking and so on.
Whatever works for you is best. However, workouts less than 60 percent of the maximum for your age may not be intense enough to promote good cardiovascular fitness.
What Your Heart Rate Reveals About You
Did you ever wonder why your doctor takes your pulse? Well, it's a quick indicator of how fit you are. The average person has a resting pulse rate of between 70 and 75 beats per minute. Fit people who get lots of aerobic exercise having resting pulse rates in the 50s and 60s. Some professional athletes have resting pulse rates as low as the upper 30s. On the other side, unfit people have resting pulse rates of 80, 90 or more beats per minute.
Any of you who take up regular aerobic exercise will notice that your resting pulse rate will drop over time -- meaning that your heart does not have to work as hard and beat as many times per minute to get nutrients and oxygen distributed to all of your body.
The best time to measure your resting pulse rate is when you first wake up in the morning and are still in bed. Even light walking will cause the heart to beat a little faster, and drinking coffee or soda with caffeine will artificially raise your pulse rate by a great deal. During the night, your body flushes out most caffeine, so taking your pulse the next day is the best true indicator of your resting pulse rate.
If you have ever had a cardiac stress test done, this test is controlled by your heart rate. You are initially at rest on a treadmill with an apparatus hooked up to you, which monitors your heart rate and provides EKG readings, among other things. The treadmill is gradually increased in both speed and incline. This continues until you reach a heart rate that's 80 percent of the maximum for someone of your age. Then the test stops.
People who are sedentary and unfit might get to their maximum in less than 5 minutes of very slow walking. A very fit runner might be on the treadmill for 30 minutes, and at the end of the test the treadmill forces the person to run fast and the incline is high. So the stress test determines how fit you are in addition to abnormalities in your heart.
How Many Beats Do I Have Left, Doc?
There's been some thinking among researchers that your heart has only so many beats in it. It will beat a certain number of times and no more. This is similar to -- and perhaps connected to -- the Hayflick limit, which has shown that most of the cells in our bodies can divide a certain number of times and no more.
There can be a dramatic difference in the number of times a person's heart beats if they are fit and unfit. Say, for example, that a fit person's heart beats 55 times per minute and an unfit person's heart beats 85 times per minute, a difference of 30 beats per minute. That difference amounts to 1,800 heartbeats per hour, 43,200 beats per day, and more than 15 million heartbeats per year. Over 20 years, the fit person's heart will save approximately 315 million heartbeats over the unfit person. That's about 11 year's worth of heartbeats!
It has never been proven that the heart has only so many beats in it because the research is impossible to do, but this idea makes sense to many. It would certainly be nice to have millions of extra heartbeats in your savings account if there is any truth to the idea.
It HAS been shown that people who get regular aerobic exercise live longer than those who don't exercise, and have other benefits such as: less cardiovascular disease, less cancer, less hypertension, less diabetes, weight loss, better brain functioning, and still many more.
For more details, see my book A Sound Mind in a Sound Body. Live long. Live healthy, everyone.