Exercised: The Science of Physical Activity, Rest and Health

by Daniel E. Lieberman

But mostly they walk. If there is one physical activity that most fundamentally illustrates the central point of this book—that we didn’t evolve to exercise but instead to be physically active when necessary—it is walking.

From a Darwinian perspective, the best strategy is to live long and actively and then die fast when you become inactive. An even better strategy, however, would be to avoid any deterioration with age in the first place.

Aging is inexorable, but senescence, the deterioration of function associated with advancing years, correlates much less strongly with age.

admirer of “libertarian paternalism,” the idea that companies, governments, and other institutions should help us act in our own best self-interests while respecting our freedom of choice.

In the eighteenth century it was fashionable to lift church bells that were silenced (made “dumb”) by having their clappers removed, hence the term “dumbbells.”

Exercise may not be an elixir, but by stimulating growth, maintenance, and repair, it can reduce our susceptibility to many of these mismatches.

The effect is akin to unclogging a drain and flushing out the pipes. Altogether, by simultaneously improving the delivery, transport, and use of blood sugar, exercise can resuscitate a once resistant muscle cell to suck up as much as fiftyfold more molecules of blood sugar. No drug is so potent.

That avoidance makes sense because, as we have seen from the very start of this book, exercise is a fundamentally strange and unusual behavior from an evolutionary perspective. Thirteen chapters later, I hope you still agree. When all is said and done, exercise—despite its manifold benefits—requires overriding deep, natural instincts.

Make exercise necessary and fun. Do mostly cardio, but also some weights. Some is better than none. Keep it up as you age.