MAIN IDEA:

The author’s main idea is to demonstrate that physical inactivity is the preferable state not only of contemporary western people but also all known hunter-gatherers. By itself, inactivity is nearly as energy-consuming as a physical activity because the primary energy expense is the process of metabolism. Nevertheless, inactivity is still detrimental to health because the human body is a machine optimized for activity. Even if hunter-gatherers prefer to be idle, they have to walk and overall be active a lot because otherwise, they would have nothing to eat. So the second part of the book demonstrates that contemporary western people should find a way to be active or pay the price in the form of deterioration of their bodies and suffering from illnesses unknown to people forced to be physically active by the circumstances of their lives.

DETAILS:

Prologue
The author discusses his discovery that subsistence farmers in Kenia, people living close to old ways, never exercise. Moreover, if left alone, they would prefer to stay in rest, as does any regular person in the developed world. He points out that humans did not evolve to exercise, but he still agrees that it is very healthy. The author defines this as a paradox and makes the following statement:” The mantra of this book is that nothing about the biology of exercise makes sense except in the light of evolution, and nothing about exercise as a behavior makes sense except in the light of anthropology.” The author also defines here the structure of the book:” After an introductory chapter, the first three parts roughly follow the evolutionary story of human physical activity and inactivity, with each chapter spotlighting a different myth. Because we cannot understand physical activity without understanding its absence, part 1 begins with physical inactivity. What are our bodies doing when we take it easy, including when we sit and sleep? Part 2 explores physical activities that require speed, strength, and power such as sprinting, lifting, and fighting. Part 3 surveys physical activities that involve endurance such as walking, running, and dancing, as well as their effect on aging. Last but not least, in part 4 we will consider how anthropological and evolutionary approaches can help us exercise better in the modern world. How can we more effectively manage to exercise, and in what ways? To what extent, how, and why do different types and doses of exercise help prevent or treat the major diseases likely to make us sick and kill us?”

One: Are We Born to Rest or Run?
The author begins with a chapter describing the Ironman endurance competition in Hawaii and the traditional footrace in Sierra Tarahumara, Mexico. He finds both grueling, arduous, and unnatural for human beings. The next step is the critic of “the myth of the athletic savage.” The author’s point is that people from the undeveloped world do not enjoy running or exercising. It is just that their everyday life forces them to apply lots of physical efforts, inadvertently preparing them for marathons and other such things. The author also reviews the UN measurement of the physical activity level (PAL) and defines it this way:” If you are a sedentary office worker who gets no exercise apart from generally shuffling about, your PAL is probably between 1.4 and 1.6. If you are moderately active and exercise an hour a day or have a physically demanding job like being a construction worker, your PAL is likely between 1.7 and 2.0. If your PAL is above 2.0, you are vigorously active for several hours a day. Although there is much variation, PALs of hunter-gatherers’ average 1.9 for men and 1.8 for women, slightly below PAL scores for subsistence farmers, which average 2.1 for men and 1.9 for women. …Here’s another, startling way of thinking about these numbers: if you are a typical person who barely exercises, it would take you just an hour or two of walking per day to be as physically active as a hunter-gatherer”.

The last part of the chapter discusses the history of exercise as nationalistic preparation for war on one hand and as the medicalized process on the other.

Part l: Inactivity
Two: Inactivity: The Importance of Being Lazy
This chapter discusses inactivity as the natural condition of humans and other primates, which are even less active than human hunter-gatherers. The author reviews research on the calories expenditure that demonstrated little difference from exercise: about 2/3 or 63% is energy spent in the condition of the rest – just to maintain metabolism. The author narrates in detail about the study conducted at the University of Minnesota during WWII that starved several healthy men, limiting them to 1500 calories until they got to extreme condition.  Here is the conclusion:” The key lesson to digest from the starving men’s dramatically lower resting metabolic rates is that human resting metabolisms are flexible. Most critically, resting metabolism is what the body has opted to spend on maintenance, not what it needs to spend.”

As clarification of this lesson, the author presents energy-use options and comparison charts:

The final word here is that inactivity, if natural and the normal condition of humans is to economize energy expense. The problem is that one had to spend energy to get food and fuel, so the tradeoff was necessary, but now we can get lots of food with practically no energy expenditure, which got us out of natural balance.  

Three: Sitting: Is It the New Smoking?
The main point of this chapter is that sitting, like any other inactivity, is not healthy and leads to inflammation and accumulation of fat. The author discusses the results of multiple research confirming this link and recommends an active sitting. The author also provides a picture supporting these points:

Four: Sleep: Why Stress Thwarts Rest
This chapter discusses another important activity – sleep. The main point here is that it is pretty personal, so recommendations of 8 hours and other such  “one size fits all” advice are usually not correct. However, the author also presents a typical structure of sleep:

Part II: Speed, Strength, and Power
Five: Speed: Neither Tortoise nor Hare
In this chapter, the author discusses the intensity of exercise and the speed of human running, comparing it with other animals. He then discusses the pluses and minuses of long runs vs. fast runs and how they impact muscles. His conclusion supports the High-intensity interval training *HIIT” and stresses that human bodies developed for various activities so that any activity would be valuable.

Six: Strength: From Brawny to Scrawny
In this chapter, the author discusses the external presentation of physics and fashion to imitate the paleo way of life.  The author reviews research on hunter-gatherers’ lifestyles and physical activities regimens. The final part of the chapter discusses muscle aging, and here is a graph demonstrating this process:

Seven: Fighting and Sports: From Fangs to Football
In this chapter, the author looks at various team sports that somewhat emulate fighting and discusses the impact of the human propensity to fight on the human body. Here is the author’s conclusion:” In the final analysis, humans are physically weaker than our ancestors not because we evolved to fight less but because we evolved to fight differently: more proactively, with weapons, and often in the context of sports. Along the same lines, we didn’t evolve to do sports to get exercise. As a form of organized, regulated play, sports were developed by each culture to teach skills useful to kill and avoid being killed as well as to teach each other to be cooperative and nonreactive. Sports took on the role of providing exercise only when aristocrats and then white-collar workers stopped being physically active on the job. Now in the modern, industrial world we market sports as a means of exercising to stay healthy (I’m still not convinced about darts). Yet true to their evolutionary roots, many sports still emphasize skills useful for fighting and hunting that involve strength, speed, power, and throwing projectiles.”

Part III: Endurance
Eight: Walking: All in a Day’s Walk; Nine: Running and Dancing: Jumping from One Leg to the Other;

In this part, the author looks in somewhat mechanical details at various activities such as walking and running. He provides a graph comparing chimps, hunter-gatherers, and westerners:

Ten: Endurance and Aging: The Active Grandparent and Costly repair Hypothesis.

The final chapter of this part looks at aging and how it developed over the ages. Here is the description of one of the experiments. It started in the mid-1960s with a group of 25 years old. The first part of the experiment looked like this:” first to spend three weeks in bed and then to undergo an intensive eight-week exercise program. The bed rest was ruinous. When they were finally allowed to arise from their beds, the volunteers’ bodies resembled forty-year-olds’ by many metrics: they were fatter, had higher blood pressure, higher cholesterol levels, less muscle mass, and lower fitness. The eight ensuing weeks of exercise, however, not only reversed the deterioration but in some cases led to net improvements.”

The second part was conducted 30 years later:” Three decades of typical American lifestyles had not been kind to the original volunteers: they had each gained about fifty pounds, had higher blood pressure and weaker hearts, and were less fit and healthy in numerous ways. But they agreed to be studied once more as they tried to undo the consequences of thirty sedentary years with a six-month program of walking, cycling, and jogging. Fortunately, this second late-in-life exercise intervention helped the volunteers lose about ten pounds and, most astoundingly, largely reversed their decline in cardiovascular fitness. After six months of moderate exercise, the average volunteer’s blood pressure, resting heart rate, and cardiac output returned to his twenty-year-old level. Many other studies confirm the anti-aging benefits of exercise.”

So, here are alternatives presented in the graphic form:

Part IV: Exercise in the Modern World
Eleven: To Move or Not to Move: How to Make Exercise Happen; Twelve: How Much and What Type? Thirteen: Exercise and Disease
This part contains multiple recommendations and “how-to” for exercise. It also provides data about the impact of exercise on various age-related diseases. Finally, the benefits are nicely summarized in these graphs:

Epilogue

Here the author summarizes the final point of this book:” Researching and writing this book has convinced me that a philosophy for how to use one’s body is just as useful as a philosophy for how to live one’s life. All of us get only one chance to enjoy a good life, and we don’t want to die full of regret for having mislived it, and that includes having misused one’s body. By following deep and ancient instincts to avoid the discomfort that comes with physical exertion, we increase the chances we will senesce faster and die younger, and we become more vulnerable to many diseases and chronic, disabling illnesses. We also miss out on the vigor, both physical and mental, that comes from being fit. To be sure, exercise is no magic pill that guarantees good health and a long life, and it is possible to live a reasonably long and healthy life without exercising. But thanks to our evolutionary history, lifelong physical activity dramatically increases the chances we will die healthy after seven or more decades.”

MY TAKE ON IT:

The philosophy and supporting research presented in this book is entirely consistent with my attitude to health and exercise issues. I believe that the human body is a biological machine evolutionary optimized for 3-4 hours of daily medium-level physical activity such as walking, picking up fruits and vegetables, setting up traps, throwing projectiles, and consequently consuming a moderate amount of food obtained via these activities. As with any other machine optimized for some conditions, it would work well and last long in these conditions and could break down if it is underloaded or overloaded. Even mechanical contraptions made of steel break down if they regularly run in overdrive or get rusty if they are not used. So it seems to be a common feature of any machine, whether made out of steel or muscles. The only thing that I do not entirely agree with the author is about types of exercise. I think it should be proportionally more helpful if it imitates the physical activities of hunter-gatherers as close as possible. Such things as bicycles, tennis, and other sports could be less efficient in maintaining the human body in good shape.