In the animal kingdom there is an interesting inverse relation between heart rate and life expectancy. For a 177 years old Galapagos tortoise with a heart rate of 6 beats/min, the 2 years lifespan with 450 beats/min of a mouse is just a blink of an eye. In general, there is a “rule”: the faster the heart rate the shorter the lifespan. The immediate consequence of this “rule” is that the total number of heartbeats in a lifetime is approximately constant and equal in most of the animal species. The only exception is … humans! According to “the rule” we should live no longer than 30 years, which actually was our life expectancy back in the days. We thank ourselves and the progress we have made in medical science for living almost 3 times longer than we should. In reality, what I have called “rule” is a gross approximation. Multiple factors that affect the basal metabolic rate have to be considered since they in turn affect the heart rate. For instance, hibernation extends life expectancy in mammals.
Read also: Exercise training reduces resting heart rate
However the fact still remains that we have a limited amount of energy available to get us from birth to death. Then, let’s consider our heart like the battery of our body. Since we cannot recharge it, can we live longer if we slow down our heart rate? As a matter of fact, wouldn’t it be great if we could live 10 years longer just by reducing our heart rate from 70 to 60 beats per minutes?
One of the beneficial effects of exercise training is indeed to reduce the heart rate at rest. Elite athletes can reach heart rates as low as 40 beats/min. Not only they potentially live longer, they have also a much stronger health, being less inclined to develop cardiovascular diseases.
In addition to energetic reasons, a fast heart rate at rest increases the risk of cardiovascular diseases which, in turn, affect our life expectancy. A fast heart rate has a direct effect on the heart and cardiovascular system: it increases the ventricular work and myocardial oxygen consumption, it interferes with repair-mechanisms of the endothelium resulting in arterial aging and damaging, it stiffens the aorta, it is associated with inflammatory processes, oxidative stress and endothelial dysfunction which accelerated atherosclerosis.
Long story short: exercise is a way to spend energy in order to make a better use of our energy. And as Neil Armstrong once said:
“ I believe every human being has a finite number of heartbeats.
I do not intend to waste any of mine.”
Read also: Where did I find the motivation to exercise?
Simona Salerno, PhD Candidate at CERG