Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

by Daniel E. Lieberman

(When I travel to places like the Sierra, I am often the only person who goes for an apparently pointless jog in the morning to the amusement of the locals.) But nearly every day of their lives, hunter-gatherers and subsistence farmers engage in hours of hard physical work. Because they lack cars, machines, and other laborsaving devices, their daily existence requires walking many miles in rugged terrain, not to mention doing other kinds of physical labor by hand like plowing, digging, and carrying.

If we really want to know what ordinary humans do and think about exercise, we need to sample everyday people from a variety of cultures instead of focusing solely on contemporary Americans and Europeans who are, comparatively speaking, WEIRD (Western, educated, industrialized, rich, and democratic).9

If you are sitting while reading this, for every five breaths you take, one pays for your brain, another for your liver, a third for your muscles, and the last two pay for the rest of your body.

How did something as normal and instinctive as saving energy become associated with the sin of slothfulness?

The mortal sin of sloth comes from the Latin word acedia, which means “without care.” To early Christian thinkers like Thomas Aquinas, sloth had nothing to do with physical laziness, but instead was a sort of mental apathy, a lack of interest in the world.

Because the anti-inflammatory effects of physical activity are almost always larger and longer than the pro-inflammatory effects, and muscles make up about a third of the body, active muscles have potent anti-inflammatory effects. Even modest levels of physical activity dampen levels of chronic inflammation, including in obese people.

It bears repeating that sleep and physical activity are inextricably linked: the more physically active we are, the better we sleep because physical activity builds up sleep pressure and reduces chronic stress, hence insomnia. In that sense, physical activity and sleep are not trade-offs but collaborators.72

We can train our bodies to do an astonishing range of things,

Obviously, bigger individuals are more likely to win because they are stronger and heavier and have longer arms with bigger fists.46 However, as in other species, size and strength are not deterministic. One point of unanimity among experts is that fighting is largely a learned skill.47 Every form of martial arts emphasizes balance, posture, developing protective reflexes, and generating force effectively with proper technique.48 Additionally, one cannot overestimate a combatant’s willingness to take risks and persevere.

To quote Rousseau: “Do you, then, want to cultivate your pupil’s intelligence? Cultivate the strengths it ought to govern. Exercise his body continually; make him robust and healthy in order to make him wise and reasonable.

The San don’t dance to get fit, but dancing all night once a week requires and develops phenomenal endurance. Further, their dancing traditions are the rule, not the exception. I know of no nonindustrial culture in which men and women didn’t dance for hours on a regular basis.

Dancing isn’t running, but it’s usually more fun and such a universal, valued form of human physical activity that we should consider it another gait akin to running. Indeed, while dancers sometimes use their legs like stilts as in a walk, most often they jump like runners from one foot to the other. And like long-distance running, dancing can go on for hours, requiring stamina, skill, and strength.

One rarely considered parallel between running and dancing is how both can induce altered states. Long periods of vigorous exercise stimulate mood-enhancing chemicals in the brain including opioids, endorphins, and, best of all, endocannabinoids (like the active compound in marijuana). The result is a runner’s or dancer’s high.

Just about everyone knows what countless studies confirm: regular physical activity slows the aging process and helps prolong life. I doubt anyone was astounded when Hippocrates wrote twenty-five hundred years ago, “Eating alone will not make a man well; he must also take exercise.”2 Endurance promotes endurance.

Aging is inexorable, but senescence, the deterioration of function associated with advancing years, correlates much less strongly with age. Instead, senescence is also influenced strongly by environmental factors like diet, physical activity, or radiation, and thus can be slowed, sometimes prevented, and even partly reversed.

Although two of three Americans’ death certificates state they died of heart disease, cancer, or stroke, the deeper underlying causes of these illnesses were most likely smoking cigarettes, obesity, and physical inactivity.

We evolved to be physically active as we age, and in turn being active helps us age well.

dopamine receptors in the brain are less active in people who haven’t been exercising than in fit people who are regularly active.

Although some people with depression take pharmaceuticals to maintain normal serotonin function, exercise has been shown to be often as effective as any prescription.21

First and foremost, let’s stop pretending exercise is necessarily fun, especially for habitual non-exercisers.

we need to be sensitive to students with disabilities and those who feel insecure, unfit, or uncomfortable about exercise. Different students have different needs, and it is wrong and counterproductive to engage in body shaming or fitness shaming. Unfit students, however, aren’t best served by not being helped to exercise, because the benefits are substantial for everyone, especially those who are the least fit. The challenge is to support and assist everyone at every level nonjudgmentally and in ways and degrees they find acceptable and rewarding.

everyone benefits from mixing it up because weights, moderate-intensity aerobic exercise, and HIIT have different, complementary effects on the body.

Exercise may not be an elixir, but by stimulating growth, maintenance, and repair, it can reduce our susceptibility to many of these mismatches. In this sense, exercise is medicinal. And unlike other medicines, exercise is free, has no side effects, and is sometimes fun. So to stay healthy and fit, many of us exercise.

while inflammation is caused by factors such as obesity, junky diets, excess alcohol, and smoking, it is substantially lowered by physical activity.

start by not smoking and by avoiding too many processed foods rich in sugar, saturated fats, and salt.

During epidemics like COVID-19, health officials urge us to wash our hands more often and more thoroughly, to practice social distancing, to cough into our elbows, and—trickiest of all—to stop touching our faces. These fundamental, sensible measures effectively help impede transmission of the virus.

In particular, weight-bearing activities that load the skeleton cause bone-growing cells to add more bone when we are young, and they prevent bone-resorbing cells from removing bone as we age.

move for the sake of your mind.

When all is said and done, exercise—despite its manifold benefits—requires overriding deep, natural instincts. So instead of shaming and blaming people who avoid exertion, we should help each other choose to exercise.

Our well-being is interconnected.