Lieberman, Daniel, Exercised: The Science of Physical Activity, Rest and Health (London: Allen Lane, 2020)
In this exploration of the science of physical activity, rest, and health, Daniel Lieberman asks why so many of us struggle to stay fit, and why our approach to exercise is so often plagued by anxiety, inertia, and confusion.
The reason, he argues, is that we never evolved to exercised; that is, we never evolved to engage in physical activity that wasn’t necessary for our survival. Our hunter-gatherer ancestors rarely spent more than an hour a day engaged in vigorous activity; the rest of the time was spent on light activities – very often sitting down – or sleeping. Put another way, we are not hard-wired for triathlons and treadmills, but for moderate exertion throughout each day.
Exercised tells the story of how we never evolved the exercise for the sake of it. Lieberman’s his anecdotes and explanations will change the way you think about exercising, not to mention sleeping, sitting, fighting, dancing, and lifting weights. He provides answers to questions that many of us will have asked ourselves or our PTs (or Google) many, many times, and helps to bust some of the most pernicious myths about exercise, ageing, and lifestyle.
Think you can’t lose weight by walking? Wrong. You can, although it might take a while.
You’ve heard that it’s normal to be less active as you age? Well, yes, to an extent, and ageing certainly requires adaptation – a longer and more gentle warm-up being the most important – but, actually, being physically active will help us to stay healthy as we age, and the right kinds of exercise will actually stimulate the repair and maintenance mechanisms required to keep us moving, and moving well.
And what about the idea that it’s impossible to get too much exercise? Well, the jury’s still out on that one. Although Lieberman is confident that you will pay the price if you exercise at extreme levels of either intensity or duration if you haven’t taken the time to adapt your muscles, bones, and other tissues to the stress of extreme exercise, he says “the negative effects of too much exercise appear to be ridiculously less than the negative effects of too little.”
But back to Lieberman’s main argument: how did exercise become ‘weird’, and why do so many people struggle to stay fit?
The discussion on exercise becoming ‘weird’ comes early in the book, and it was one of my favourite sections. Lieberman draws the distinction between activity and exercise – obvious, but important – then explains how exercise for fitness evolved in the ancient world as a means to ensure the population was combat-ready, as Lieberman explains: “paintings from pharaonic Egypt and Mesopotamian carvings testify that sports like wrestling, sprinting, and javelin throwing helped would-be warriors keep fit and hone combat skills.”
Very often, those would-be warriors were also farmers, but not all exercise in the ancient world was combat-related. “If you were wealthy enough to attend one of the great Athenian schools of philosophy, you would have been advised to exercise as part of your overall education. Philosophers like Plato, Socrates, and Zeno of Citium [that’s the guy who founded Stoicism, by the way] preached that to live the best possible life, one should exercise not only one’s mind, but also one’s body.” They were not wrong.
Exercise for fitness was not so common during the Dark Ages, but came back into fashion during the Renaissance (from around 1400 onwards) but only for the upper classes. Between the fifteenth and seventeenth centuries, educators and philosophers “advocated exercises like gymnastics, fencing, and horseback riding for the elites to promote vigor, teach character and values, and enrich minds.” Later, during the Enlightenment and Industrial Revolution – so from around 1685 into the nineteenth century – thinkers and “liberal luminaries enthusiastically extolled the natural value of physical activity and fitness to growing numbers of the newly affluent.”
So it was that we learned the value of unnecessary and voluntary physical activity, and now we not only promote it, we have also medicalised, commercialised, and industrialised it, and that, apparently, is what makes it ‘weird’: “What would my distant hunter-gather ancestors have thought of paying lots of money to suffer through needless physical activity on an annoying machine that gets us nowhere and accomplishes nothing?” asks Lieberman.
Whether it actually accomplishes nothing is a debate for another day, but seen through that lens, it’s no surprise that so many people struggle to motivate themselves to exercise. And Lieberman is right when he says that “engaging in voluntary physical activity for the sake of health and fitness is a bizarre, modern, and optional behavior. Like it or not, little voices in our brains help us avoid physical activity when it is neither necessary nor fun.”
Fair enough. And, since Lieberman argues that we cannot make exercise necessary or fun – voluntary physical activity is simply too unrewarding and inconvenient for many people – we must work out how to make it more fun and more necessary.
The fun part should be easy. Most of us know the high we get after a really good workout thanks to the rush of dopamine, endorphins, endocannabinoids, and serotonin that is released by physical activity; it’s “not unlike taking an opioid”, apparently. But, paradoxically, that flood of pharmaceuticals primarily rewards people who are already physically active. For those struggling to take the first step, Lieberman offers other ways to make exercise fun, such as making it social, listening to good music, exercising in a beautiful space, and mixing things up to keep it varied and interesting. All good advice.
As for whether we can make exercise more necessary, Lieberman discusses – and dismisses – mandating exercise for adults, but recommends self-imposed ‘nudges’ and ‘shoves’ to help turn new, optional behaviours into non-negotiable habits. Forms of self-coercion Lieberman suggests include setting out your exercise clothes the night before, scheduling exercise with friends or a group so you are obligated to show up, or, at the more extreme end, sign a commitment contract that rewards you for completing your workouts.
Overall, Exercised is entertaining and enlightening but also constructive, full of solid information and fascinating observations. For those of you who aren’t as interested in the evolutionary aspects of exercise as me, there is plenty more science and physiology to uncover: the chapters on speed and strength are especially good, as is the discussion on the science of sleep.
And, after almost 400 pages of solid but readable science, Lieberman presents his own tl;dr: “Make exercise necessary and fun. Do mostly cardio, but also some weights. Some is better than none. Keep it up as you age.” That sounds doable to me.
This awesome review was written by the great Sarah W.