Three Important Heart Rate Numbers

exercise-heart-heartA healthy heart varies its pulse rate rapidly in response to demand. The heart rate at three key spots can help tune up your exercise and general heart health.

Resting heart rate, maximum heart rate during exercise, and heart rate recovery after peak exercise all provide substantial information about heart attack risk. (Again, don’t attempt extreme exercise without your doctor’s blessing.)

An interesting paper on the effects of these heart rates on heart attack likelihood can be found here. A quick summary. Those with a resting heart rate over 75 bpm (beats per minute) had a fourfold higher risk of dying from heart-attack or stroke than those 60 or less. For peak heart rate, those whose peak was less than 90 bpm higher than their resting heart rate also had a four-fold higher risk than those whose peak rate exceeded their resting rate by more than 113. Finally, for recovery after peak exercise, those whose heart rate dropped less than 25 bpm one minute after peak exercise had more then a twofold risk increase over those whose rate declined by more than 40. These are pretty strong results and provide a very immediate way to gauge the effects of exercise on heart health. It should go without saying that with the correct exercise regime, consistently applied, all these heart-rate numbers can be improved, often markedly.

Measuring Heart Rate

Resting heart rate should be taken before you get out of bed in the morning. No coffee, no movement. Any means of measuring it is fine

The peak rate and the recovery rate are dynamic measurements (rapidly changing) and some sort of real-time monitor will be needed. The response time should be under 5 seconds. (Sorry, gadget freaks, the Apple watch wont cut it.) Many of the pulse-rate-measuring watches are fast enough. Those that require a chest belt are by far the best.

Heart Rate Variability and Biological Power

Most health sites, and many doctors, recommend mild aerobic exercise in varying forms and degrees. While better than nothing at all, it would be hard to characterize this form of exercise as particularly good. Brisk walking 2½ hours per week or jogging 1¼ hours per week are common.

Age Max heart rate (beats/minute)
55 140
60 136
65 132
70 127
75 123

There are also frequent recommendations to keep your heart rate below a certain level. The level is a relatively low one. Here are some typical numbers:

Ostensibly this is done in the interest of safety, but it has exactly the opposite effect. To preserve heart health and prevent atherosclerosis, it is necessary to run the heart up and down through all its possible pulse rates, including its maximum.

The chart is computed from some rules of thumb. Rule of thumb #1 is this: your maximum heart rate is 220 minus your age. Runf thumb #2: the exercise target is 80% of that. Now this one-size-fits-all formula is patently absurd. A maximum heart rate for a 65-year-old who exercises vigorously would probably be closer to 175 beats per minute than the 132 given in the chart.

These low heart rates correspond to a “standard medical practice” that seems to have a strange life of its own. There is absolutely no science, good, bad, or otherwise, supporting these low heart rates, nor has there ever been. It is some sort of superstition. There is no medical literature, past or present, that shows higher heart rates to be dangerous. On the other hand, there is a large body of science supporting the concept that varying the heart over its full range has huge health benefits and dramatically reduces heart risk.

Aerobic exercise is better than no exercise at all, but not by much. Keeping your heart rate moderately elevated for extended periods of time trains your heart and lungs to, well, stay moderately elevated, and, as you might suspect, this is only moderately beneficial.

However, moderate elevation of heart rate, even if prolonged, won’t begin to accomplish the physical and cellular changes necessary to avoid degenerative disease and slow aging. More intensity is needed. The heart needs far greater variability, including brief periods of maximal output. The arteries and veins need the temporarily elevated pressure and rush of blood that accompanies it. Only by punching through the barriers that aerobic exercises impose can greater heart health be obtained.

How Safe Is It?

Get an OK from your doctor, but insist that he or she justify any seeming low maximum.

We are proposing running the heart to its maximum rate for short bursts. For which group of people might this be dangerous? Short answer: If you have no significant cardiac risk, we believe it completely safe. For most with cardiac risk, it is also safe. Further, such exercise vastly reduces overall cardiac risk for everyone. But with no trouble at all, you can find recommendations to limit your heart rate. For a 70-year-old, the usual limit is 127 beats per minute. This is very low, and the results from exercising with this restriction will correspond.

American Heart Association has one-size-fits-all recommendations such as these on their website, but they also have a lot of good medical research there as well. In one paper, they investigated the safety of “maximal” exercise. Maximal exercise comes in many flavors, but will usually imply maximal heart rate, or at least a heart rate well above the lame standard limit. Out of 72,000 reported maximal tests, there was one reported cardiac death. In the last 10 years, none at all. This is safer that most daily activities, and of course, the reduction of cardiac risk resulting from such exercise will save many, many people, likely tens of thousands, from cardiac death.

There are three categories of people that should avoid maximal exercise:

  • If you have valvular disease, some defect in the valves of your heart, more than usual care should be observed. In such a case, be guided by your last echocardiogram and your cardiologist’s advice. He may be too restrictive, but no general advice can be offered here.
  • If you have mechanically unstable coronary artery disease, sometimes the shear forces that are otherwise good for the heart might “shake loose” some of the detritus and trigger a clot and subsequent occlusion or blockage, leading to a heart attack. This sounds so vague as to warrant the usual generic and tepid advice to severely limit your heart rate during exercise. Please do not hear this point in that way; superstition is not necessary. If you have any family or personal history of heart attacks, you should nail down this risk by coronary calcium scoring and other additional measures to assess any such risk. If you and your cardiologist think this is a real risk, still don’t keep your heart rate as low as the table demands, but do proceed with more than usual caution.
  • If you have a known serious heart conduction defect that has been clearly shown to be triggered by higher heart rates, and is potentially life threatening, then certainly observe the heart rate limits your cardiologist suggests. This electrical problem should be respected, though even here we are more likely to recommend this be repaired than drugged.

A follow-up post will delve into exercises that can achieve these desired heart rate variabilities.

 

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