1 The Long Decline of Everyday Movement
Given this is the story of how our lives have changed so dramatically with the disappearance of everyday physical activity, itâs probably best to start at the beginning. And that might be slightly longer ago than you expected. About 12,000 years, in fact.
It was around this time that some of our Neolithic ancestors in what is now the Middle East gave up their hunter-gatherer lifestyle and, over numerous generations, began instead to cultivate crops, domesticate animals and form permanent settlements. This is, of course, not particularly long ago by the standards of human history â Homo sapiens had emerged anything up to 300,000 years earlier â but what is now known as the First Agricultural Revolution, or Agrarian Revolution, was the beginning of a settled, more densely populated life, helping bring about the development of new tools, then the specialisation of labour. In other words, the building blocks for modern civilisation.
Any 21st-century human suddenly catapulted to one of these first villages would find life there hugely gruelling and overwhelmingly physical. But it was still more sedate than the hunter-gatherer existence, free of the endless miles of walking required to forage and hunt for prey. And so, over the centuries, something began to happen to these early, home-dwelling humans: their bodies changed.
It has long been known that modern humans have considerably less dense bones than similar-sized primates, something often linked to our distinctive upright walking stance. But a fascinating 2014 study by US and British academics found that bones from humans who lived in hunter-gatherer communities in North America around 7,000 years ago (the agricultural revolutions did not happen everywhere simultaneously) were as strong and dense as those now seen in orangutans. In contrast, bones examined from farmers who lived 700 years ago were 20 per cent lighter. The researchers concluded that this âgracilityâ of the more modern skeleton, a rather lovely technical term meaning âslendernessâ, was not caused by a changing diet, or by different body sizes as humans evolved, but simply because of reduced physical exertion.1
Such change has very modern consequences. Human bone density is significantly affected by how active someone is, particularly during childhood and adolescence, with weight-bearing movements like running and jumping key to this development. Bone density usually peaks in early adulthood and then declines as we age, particularly with women, and all the more so through long-term inactivity. Loss of bone density increases the risk of fractures or the debilitating condition of osteoporosis, another evocative technical term which literally means âporous bonesâ. The health impacts are enormous. Studies have shown that among older people who suffer an osteoporosis-related hip injury, up to 20 per cent die in the first year, and two thirds never regain the same level of mobility.2
There is some important context to be added: in activity terms, these farmers clearly had much more in common with hunter-gatherers than with todayâs humans, so any bodily changes were relative. Another study examined bone mass in women from other early agricultural communities, this time in central Europe. It found that while the bones in their legs were generally comparable to those of modern women, with their arms it was a very different story. The humerus, or upper arm bone, showed rigidity and indications of strength comparable or even greater than that of modern-day elite female rowers. These women clearly carried or hoisted sizeable loads on a more or less daily basis, and they had the bone density to prove it.3
Gathering a more detailed picture of our ancestorsâ physical lives is, understandably, not easy, short of using a time machine to attach an activity tracker to a prehistoric farmerâs leg. One creative part-answer has come from studying people whose lifestyles have at least something in common with those from the past. A fascinating project saw academics examine activity patterns in a community of Amish people in Ontario, Canada. The Amish are a Protestant group that originated in Switzerland but came to North America in the eighteenth century. As well as following a creed of non-violence, they pursue traditional values to the extent of rejecting all modern technology, meaning that â as regularly portrayed in films and television â their methods for everything from agriculture to travel involve nothing more high-tech than horses and hand-tools.
Luckily for researchers, Amish rules do not completely bar them from using modern inventions, just owning them. That meant the ninety-eight Amish men and women who took part were able to spend a week with an electronic step counter attached to the waistband of their trousers or to an apron â one slight complicating factor was that the Amish are forbidden to wear belts.
When the results arrived, they were striking. Separate surveys have calculated that the average Canadian adult walks just over 4,800 steps per day. In contrast, the Amish men averaged almost 18,500. Even the communityâs women, who traditionally spend most of their time in domestic and child-rearing activities rather than farming, managed well over 14,000 steps.
The highest individual one-day total was 51,514 steps, more than 20 miles, recorded by an Amish man who was harrowing farmland, the process of smoothing and breaking up soil, while walking behind a team of five Belgian horses. The best for a woman was the 41,176 steps achieved by a farmerâs wife who rose at 3:30am to assist with the agricultural chores before beginning her own domestic duties. In such a world the idea of âexerciseâ seems redundant. Of the men and women studied, only two â both men â listed leisure activities in the accompanying activity questionnaire, mentioning fishing.4
It is a very long time since Amish-style levels of exertion were the norm in places like the UK, a factor of both mechanisation and a shift away from rural life. Britain experienced a particularly early exodus of agricultural populations to factory jobs in towns and cities, with the countryâs rate of urbanisation soaring from below 50 per cent in 1840 to nearly 80 per cent by the end of that century.5 But even decades after that, up to the post-war era of the 1950s, although for many people the repetitive physical grind of manual factory labour had been replaced by sedentary work, other aspects of life remained significantly more active than we experience now.
How do we know this for certain? One innovative experiment saw a group of volunteers fitted with sensors to measure how much energy they expended, before being set to work carrying out a series of identical household and transport activities in two different ways. They washed a selection of dishes in a sink, and then loaded the same number into a dishwasher. Dirty clothes were laundered by hand, then re-dirtied and put in a washing machine. An imaginary 0.8-mile commute was done on a treadmill to simulate walking, and then by car. Finally, our long-suffering test subjects ascended and descended a series of floors using the stairs, before doing so in a lift.
The results showed that hand-washing dishes and clothes was, as you would expect, more strenuous than the automated versions, by 40 per cent and 55 per cent respectively. But much greater differences came when the whole body was in motion. The simulated walking commute and the stair climbing were both more than three times as strenuous as letting machinery do the work. Factoring in how often people tend to perform all these tasks on average, the researchers calculated that these modern conveniences meant people now expend 111 fewer calories per day on average.6
This might not seem much, given the recommended daily intake is 2,500 calories for men and 2,000 for women.7 But as the research paper pointed out, dropping your energy expenditure by 111 calories a day without a parallel reduction in food intake brings an average weight gain of more than 4kg a year, which is a relatively rapid path towards obesity.
Steven Blair is emeritus professor at the Arnold School of Public Health at South Carolina University. He is one of the worldâs leading experts on how everyday movement has disappeared from the world, and the consequences. Blair was the lead editor of a landmark 1996 report by the US Surgeon General into activity levels, which kicked off much of the modern era of government guidelines on the subject.8 He is also, incidentally, one of the pioneers of the idea that it is far better for your health to be overweight and active, rather than slim and immobile, which weâll hear more about later.
Blair is now aged eighty, old enough to remember first-hand how much things have changed in the home. âDo you want me to tell you who is the real cause of all of these problems?â he tells me, his voice crackling with energy and mischief down the phone. âIt was James Watt, inventing that steam engine. But to be serious, weâve been engineering human energy expenditure down and down. I grew up on a farm in Kansas, and I didnât have to do any exercise. I worked my tail off. At 5:30am Daddy would make me go out and get those cows in, and milk them, and feed them, and work all day. Thank goodness I did go to school, so there were a few hours during the school year when I didnât have to be out there.
âI remember when my grandma got a vacuum cleaner. I think it was 1944. And when my parents got electricity out on the farm, I didnât have to carry all those logs in for Mom to put on the stove to cook dinner. On and on and on weâve engineered human energy expenditure, down and down and down. Iâm not saying we shouldnât have these modern, wonderful devices, but what it means is, weâve got to find ways for people to build a little more activity back into their lives.â9
A world immobile
Seven-plus decades on from the Blair familyâs first vacuum cleaner, how inactive are we as a species? The short answer is: very â and probably even more so than even the official statistics indicate.
The long-standing way for academics to assess activity levels has been to use questionnaires. But as Blair or any other researcher of a similar vintage will resignedly tell you, people cannot always be trusted. My favourite summary comes from James Skinner, a now-retired professor of exercise science at Arizona State University, who once wrote, wisely: âAs a general rule, people overestimate what they do, and underestimate what they eat.â Skinner cited a US study in which people were asked to name which sports they took part in. Even allowing for some of them engaging in more than one sport, the number of people who reported doing just the top ten activities was greater than the entire population of the United States.10
Directly monitoring individual movements is now far easier, thanks to the advent of electronic activity tracking, familiar to anyone who has browsed the step count statistics on their smartphone. Many studies now use tiny, Bluetooth-connectable devices, which can feed researchers 24-hour flows of data about every movement and rest, however small or brief. I managed to borrow one of these research-grade devices to track my own activity levels, with eye-opening results, as weâll see later in the book. All that said, when it comes to population-wide studies, especially ones comparing countries, much of the information still tends to be based on surveys and questionnaires. As such, however gloomy the global activity averages, it should be remembered that things are probably worse in real life.
When researchers investigate whether people are considered inactive, thus risking their long-term health, the standard metric is failing to reach at least 150 minutes a week of moderately intensive activity, or 75 minutes of vigorous activity, ideally spread out over five or so days and in bouts of at least ten minutes. The precise definitions of moderate and intense are slightly complex, and I will detail them in the next chapter. But there are countless lists of suggested activities which give a good general idea. For example, moderate activity covers things like walking at a brisk pace, and more strenuous housework chores such as vacuuming, and gardening. To reach intense exertion levels you need to be running, or cycling fairly quickly, or doing difficult manual work like digging a ditch.
This 150-minute gauge has become more or less universal, and is used by the World Health Organization (WHO), Public Health England (PHE) and the US Department of Health, among others. It must be remembered that this is just a minimum level seen as necessary to maintain health, and yet many millions of people donât get anywhere near it. The latest figures for England show that for adults, 66 per cent of men and 58 per cent of women meet these guidelines.11 This is, however, only part of the story. A more recent but now equally ubiquitous global recommendation from PHE, the WHO and others is that to preserve bone strength and prevent muscle wastage as people age, adults should do some sort of strength-based activity twice a week, whether lifting weights or something like carrying heavy shopping. When the requirements for both aerobic and muscular activity are taken into account, the proportion of people who reach the minimum falls to 31 per cent of men and 23 per cent of women.12
The picture gets notably worse when it comes to children. They should aim for an hour of moderate-to-vigorous activity every single day, with those aged under five active for at least three hours daily. In fact, the UK guidance for the latter age group says children so young should never be immobile for long periods, apart from when theyâre asleep. But in the UK, only 22 per cent of those aged five to fifteen are reaching the minimum, a figure that declines below 15 per cent in adolescence. Even worse are the statistics for the youngest children, aged two to four, whose mandated three hours a day of movement is vital to lay down bone density and build muscles, as well as acquire the motor skills needed for life. Just 9 per cent manage this.13
The UK is no outlier. In fact, in global terms it is broadly typical. Just over a week before the opening of the 2012 London Olympics, revered medical journal The Lancet devoted an issue to what it described as the worldwide âpandemic of physical inactivityâ. While the edition was timed to coincide with a sporting event, the stress was very much on everyday activity. âIt is not about running on a treadmill, whilst staring at a mirror and listening to your iPod,â the Lancet editors wrote in an introduction. âIt is about using the body that we have in the way it was designed, which is to walk often, run sometimes, and move in ways where we physically exert ourselves regularly, whether that is at work, at home, in transport to and from places, or during leisure time in our daily lives.â14
Among the papers was a study by a team of academics seeking to quantify for the first time the global extent of inactive lifestyles. Led by Pedro Hallal, a Brazilian epidemiologist, it took data from just under 90 per cent of the worldâs population, using a recently agreed standardised international physical activity questionnaire, allowing for the first time robust comparisons between countries and regions.
The headline figure was that 31.1 per cent of people aged fifteen or older were insufficiently active. For those aged thirteen to fifteen, four in five across the world were not meeting the targets.
The study also uncovered the sheer variation across regions, countries, genders and ages. While 43 per cent of adults were inactive in the Americas, this fell to 17 per cent in southeast Asia. Between individual nations the difference was more extreme still, going from fewer than 5 per cent of people not meeting activity guidelines in Bangladesh to very nearly 80 per cent in Malta, the Mediterranean island which despite its idyllic holiday des...