Exercised: The Science of Physical Activity, Rest and Health by Daniel Lieberman

Author:Daniel Lieberman [Lieberman, Daniel]
Language: eng
Format: epub
ISBN: 9780241309285
Publisher: Penguin Books Ltd
Published: 2020-09-02T16:00:00+00:00

Extending or Compressing Morbidity

My high school required us to take a class in health education that replaced a semester of physical education. Instead of climbing ropes or playing basketball, we were sent to a dingy classroom underneath the school gym where our portly, florid teacher often paced up and down the aisles, thumbs tucked behind his suspenders, and lectured loudly about health. I don’t remember a single fact or counsel he imparted apart from his declaring that he could tell from our earlobes if we smoked pot and that 90 percent of all smokers who get lung cancer die. When a smart aleck friend (not me, really) asked if it wasn’t the case that all people who get lung cancer eventually die, he roared back that, no, only 90 percent died. Then, one shocking day, we showed up to class and were informed by a substitute that our health teacher had died of a heart attack—an unintended, posthumous lesson.

We all die of something, and if you are following my argument in this chapter skeptically—as you should—that includes physically active people who eat sensibly and do everything else they are supposed to. In fact, despite being told to exercise, more inactive people like Donald Trump are living longer and in better health today than ever before.

To evaluate this conundrum, let’s look closely at the probabilistic relationship between death (mortality) and illness (morbidity). Too often, statistics on aging focus on life span without also considering health span (the length of time spent in good health without morbidity). A useful way to think about both life span and health span is to graph functional capacity (a measure of health) on the y-axis versus time on the x-axis, as shown in figure 28. Someone who is generally healthy is at nearly 100 percent functional capacity most of the time, despite occasional, temporary illnesses. Then, at some point, age-related senescence commences and functional capacity declines because of serious illness, eventually leading to death.

For thousands of generations, the health span and life span of a typical hunter-gatherer who did not die in infancy probably looked something like the top graph in figure 28. The graph is based on medical surveys of hunter-gatherers, who mostly die from respiratory and infectious diseases, violence, and accidents and have a relatively low incidence of long-term chronic noninfectious conditions.55 These and other data indicate that about two-thirds of older hunter-gatherers remain at high functional capacity with limited morbidity until just before death, which most often occurs in the seventh decade. Accordingly, their health span and life span are very similar.

Advances in public health and medical science have changed health span and life span in ways both good and bad, illustrated by the bottom graph in figure 28. The bad news is that despite impressive advances in preventing and treating infectious diseases, many people today get sick from chronic noninfectious diseases that involve many years of morbidity prior to death. In medical jargon, this longer period of illness prior to death is termed the extension of morbidity.

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