Adam’s journal
A fellow runner recently asked me a question that left me scratching my head. She’d heard a theory that each of us has an allotted number of heartbeats in our lifetime. If that’s the case, she wondered, do people who exercise — which elevates heart rates — use up their lifetime supply of heartbeats faster than couch potatoes?
Dr. Prescott prescribes
Well, let’s start with some math. An average resting heart rate can range from 60 to 100 beats per minute, but for this example, let’s call it 75 beats per minute. That means this person’s heart would beat 108,000 times a day.
When you exercise, your heart rate increases substantially. For vigorous exercise, your heart might reach a sustained rate of 150 beats per minute. If you kept up your routine for an hour, that would translate to 9,000 beats for one hour.
But exercise also has the effect of slowing a person’s resting heart rate, with highly conditioned athletes often having resting pulses in the range of 40 to 50 beats per minute.
Assuming a resting heart rate of 50 beats per minute, the heart of the well-conditioned person would beat another 69,000 times over the remaining 23 hours of the day. Add that to the hour of exercise, and you get a daily total of 78,000 beats.
That means our jogger (or swimmer, aerobicist or bicycler) has a heart that beats 30,000 fewer times a day. Over a year, that’s almost 11 million beats conserved. And over 70 or 80 years, the figure approaches 100 million.
Obviously, these numbers will vary a bit.
But the lesson remains the same: Exercising saves heartbeats.
That said, I should also tell you that there is no fixed number of heartbeats per human life span.
The “rate-of-living theory” is an ancient explanation of longevity that hypothesized that aging occurs due to the exhaustion of something finite such as heartbeats or breaths. Perhaps it finds its origins in the animal kingdom, where hummingbirds (whose hearts can beat more than 1,000 times a minute) rarely live more than a few years, while slow-pulsed elephants (30 beats per minute) routinely survive to the ripe, old age of 70.
But scientific studies have debunked this theory in humans. Indeed, by extending our lives by an average of 30 years over the last century, modern medicine has greatly increased the number of heartbeats each of us enjoys in our lifetimes.
For optimal heart health, there are some simple steps you can take. First, don’t smoke.
Also, control your weight, cholesterol and blood pressure.
And what’s one of the best ways to control these factors?
Exercise, of course.
