Innholdsfortegnelse for EG16 i New Scientist - The Essential Guides

THE human species was made to move. In recent years, research has overturned many of our assumptions about what exercise does for us, and revealed quite how vital it is to our health and well-being. It is little surprise that physically activity has come to be seen as a wonder drug, essential for the body and mind to function at their best. This wealth of old and new information has led to us being bombarded with advice in the media and from health bodies about exercise, but not all of it is grounded in the latest evidence, or any evidence at all. The aim of this Essential Guide is to cut to the facts about exercise and why it really is the best thing you can do if you want…

Runners and other active people tend to live longer. But if these bonus years are equivalent to all the time spent working up a sweat throughout life, then is it all a waste of time? It is a pertinent question for those who find exercise a penance. Duck-chul Lee of Iowa State University and his colleagues dug into the data to find out. They calculate that between the ages of 44 and 80, someone who runs 2 hours per week will spend a total of 0.43 years running. This would still provide an average “bonus” of 2.8 additional years of life on top of the time spent running. In other words, 1 hour of running typically adds an extra 7 hours to lifespan. “It is controversial whether progressively more running…

“I BEND SO I DON’T BREAK.” No one knows who first coined this phrase, but search for it online and you will find it accompanying numerous pictures of yogis in various states of contortion. Flexibility, according to common wisdom, is not only impressive to look at, but something we should actively work towards. Scientifically, however, the question of whether we should stretch to become more flexible has been difficult to answer. Even in sports science, where most of the research has been conducted, there has been little agreement. See the opposite page for more on stretching before exercise In recent years, though, answers have started to emerge. The surprising outcome is that, while stretching may well be good for us, it is for reasons that have nothing to do with…

Many gym bunnies live with headphones in their ears, and that could be a good idea. For starters, listening to tunes can ease the pain of a workout, to the extent that music has been likened to a performance enhancing drug – albeit a legal one. Listening to tunes while you exercise can improve power, strength and endurance. But your choice of drug matters: achieving the runner’s high might be easiest when the music’s tempo matches your own. It turns out we unconsciously move to the beat of our playlist. When researchers secretly sped up or slowed down music that cyclists were listening to, they quickened or eased their pace accordingly. Choosing songs that match the rhythm at which we cycle or run can make exercise feel like a breeze.…

It is the perfect carrot to dangle if you are more likely to be sliding off the couch than running out of the door: exercising at lower intensities can burn more fat than a strenuous workout. This idea of the “fat-burning zone” starts with the fact that the body can quickly turn carbohydrates into fuel, so they are called upon in an intense workout – whereas fat is burned more slowly, making it an ideal fuel for a slower pace. Unfortunately, that is a bit of a confusing message. At very low intensities, we burn proportionally more fat than carbohydrate – but the amount of both burned will be much higher at higher intensities. So unless you are prepared to keep going for a very long time, you are better…

GLOBALLY, falls are the second biggest cause of accidental death after traffic accidents. Between 1990 and 2017, the total number of deadly falls around the world nearly doubled. Risk of losing your balance increases with age, so you might think this simply reflects the huge number of baby boomers entering their twilight years. But recent estimates suggest the incidence of falls is rising at a rate that outstrips what would be expected from a growing, ageing population. Instead, scientists are now taking a closer look at the complex brain-body interactions that underpin our ability to balance, and the ways that it is tied to both cognitive and emotional processing. This system is remarkably complicated, but it turns out that the problems undermining it are relatively simple to pin down. It…

NUMEROUS studies have demonstrated that exercise can improve our cognitive functions and enhance the production of brain chemicals that help us feel motivated. The problem is that exercise and motivation can have a cyclical relationship: you have to be motivated to get moving in the first place. In 2018, Matthieu Boisgontier, a neuroscientist at the University of Ottawa in Canada, looked into a paradox involving exercise – even though the vast majority of us intend to be physically active, many don’t do any exercise at all. Boisgontier and his colleagues found that the brain has to exert more effort to avoid sedentary behaviours than it does to just go along with them. This led him to conclude that humans have an “automatic attraction to effort minimization”. Boisgontier argues that our…

While there’s currently no workout pill that can replace exercise, there are some that could add to your workout. Vitamin D3 supplementation appears to have an effect on muscle strength. In one study, for example, elite ballet dancers received D3 supplements over winter, resulting in a 19 per cent increase in quadriceps strength and fewer injuries compared with dancers who took a placebo. It isn’t clear how this vitamin helps, but it is known to affect a complex process of events that control calcium levels, which are involved in the mechanisms that help muscles contract. Or you might try a little vibration. Machines that vibrate your body while you work out became popular in the early noughties, but there were few studies to back their use. Now, though, evidence suggests…

OUR gut microbiota – the organisms living within our digestive tract – are increasingly being implicated in many aspects of human health. In recent years, that role has been extended to exercise. We know exercise can alter the gut microbiome, but now George Church at Harvard University and colleagues say that the microbiome may be a critical component of physical performance. The Boston marathon is famously tough to get into, due to its ever-faster qualifying times, so those taking part make a perfect testbed for the relationship between the microbiome and fitness. The researchers took daily stool samples from 15 runners in the 2015 race, one week before and one week after they ran, along with a sedentary control group, to see what was in their gut. A genetic analysis…

Early humans, we always thought, first struggled onto two feet after a long period of gorilla-like knuckle-walking. But a newer hypothesis suggests that our move to bipedalism began much earlier, at a time when our ancestors were still living in the trees. According to this line of thought, about 15 million years ago, our tree-dwelling ancestors began to spend more time standing up, at first holding onto branches with their hands and gradually balancing independently. One study found that even lightly touching a moving branch with the fingertips provides enough sensory feedback to the brain to stay balanced. If this is true, then learning to balance is an integral part of what made humans what we are today. Turn to page 72 for more on balance…

THE idea that running is the best exercise for us – indeed, that it is part of what makes us human – has many champions. Among them is Daniel Lieberman at Harvard University, who maintains that we evolved to run long distances. He thinks that our now largely untapped talent for persistence hunting – chasing animals over long distances – in hot conditions gives us an edge over other animals and shaped our evolutionary history. Turn back to chapter 1 for more onwhy we are born to run And we aren’t just good at running because we are good at walking – technically they are quite different. A range of adaptations such as sweat glands and hairless skin to aid cooling, the right balance of muscle types and a special…

“ OUR MINDS AREN’T PASSIVE OBSERVERS SIMPLY OBSERVING REALITY AS IT IS; OUR MINDS ACTUALLY CHANGE REALITY. THE REALITY WE EXPERIENCE TOMORROW IS PARTLY THE PRODUCT OF THE MINDSETS WE HOLD TODAY. ” That’s what Alia Crum told global movers and shakers at the World Economic Forum in Davos, Switzerland. It may sound like New Age nonsense, but Crum, who heads the Mind & Body lab at Stanford University in California, can back up her claims with hard evidence showing the mysterious influence the mind has over our health and well-being, including the impact that exercise has on us. Crum’s pioneering research was inspired by her own experiences as a child gymnast and college ice hockey player. “You can be the same physical being from one day to the next,”…

IN FRANCE, in the winter of 1782, the chemist Antoine Lavoisier and his polymath friend Pierre-Simon Laplace placed an unwitting guinea pig into a double-walled metal chamber, the world’s first calorimeter, and sealed the lid. They had packed snow into the space between the walls, and by comparing the rate at which the guinea pig’s body heat melted the snow to the rate of carbon dioxide it exhaled, they discovered metabolism – the “fire of life” that drives our very existence. At last, science had a physical measure of the life force that enables us to grow, reproduce and move. Physiologists have been counting calories ever since. Even so, Lavoisier and Laplace might be surprised at the place their discovery plays in the collective psyche of the millions of people…

THERE are five places around the world that have become renowned for the fact that their inhabitants tend to live the longest, healthiest lives of anywhere on the planet. In all of these places, which have the highest concentrations of centenarians, physical activity is a way of life. And in Ikaria in Greece, Loma Linda in California, Nicoya in Costa Rica, Okinawa in Japan and Sardinia in Italy, dementia and cognitive decline are 75 per cent less frequent than throughout most of the Western world. Decades of research concludes with overwhelming evidence that aerobic exercise has beneficial effects on the brain, including improved mood and thinking skills. Exercise reduces inflammation, which can inhibit the growth of new brain cells. If that weren’t enough, exercise actually increases neurogenesis, or the growth…

ANOTHER blistering afternoon in northern Tanzania, another highstakes game of musical chairs. Stumbling back into camp to escape the sun, desperate for a seat, we glanced at each other and then at the single unoccupied camp chair. In the other, grinning, sat Onawasi, a respected elder with a mischievous bent. He seemed to be enjoying this. We were spending our summer with the Hadza community, one of the last populations of huntergatherers on the planet. Hadza men and women manage to avoid heart disease and other diseases of the more industrialised world, and we wanted to understand why. Our small research team had come in two Land Cruisers loaded with tech to measure every movement made and calorie burned as Hadza men and women scoured the landscape every day for…

IT IS a shocking fact that many of us today are almost entirely sedentary. The current US and UK government guidelines for physical activity recommend that adults do at least 2.5 hours of moderate exercise or 75 minutes of vigorous exercise every week. In the US, only half the population meet these guidelines, and the situation is only slightly better in the UK. But to work out whether you are doing enough, you first need to know what counts as moderate and vigorous. Physical activity is any type of movement that uses up energy. So you can think of exercise as a type of physical activity that is done in a structured way and has as its goal some sort of physical fitness – though as we will discover in…

FIRST, the obvious benefits: exercise keeps our muscles and hearts strong, our blood vessels pliant and improves aerobic fitness. When we get our heart rate up, the stresses imposed by the blood rushing through our arteries promotes the production of nitric oxide, which helps repair blood vessels and keep them elastic. Maintaining strength and aerobic fitness is particularly important as we age. Older adults who can cover at least 365 metres in a standard 6-minute walking test have half the risk of dying in the subsequent decade as their peers who can’t make 290 metres. Additional robust evidence comes from the Exercise is Medicine initiative pioneered by the American College of Sports Medicine in Indianapolis, Indiana. Researchers there have collated studies over decades looking at people who follow the US…

In the mid-1960s, a small, plastic pocket watch-like device went on sale in Japan. Called the “manpokei”, it was the world’s first commercial pedometer. Roughly translated, manpo-kei means “10,000 steps meter”. Why 10,000? “It likely originated as a marketing tool,” says I-Min Lee, an epidemiologist at Harvard University. Not only is 10,000 an easy number to remember, the character for 10,000 in Kanji, a script used in Japanese, looks a little like a person walking. This health target, then, didn’t originate with science. Can we scrap it and have a nice sit down? As we’ve already seen, one way to investigate such questions is to look to our past way of life. Studying the Hadza, hunter-gatherers in Tanzania, as a window into how humans lived thousands of years ago, and…

When people walk, at least one foot is always touching the ground. It is an efficient technique in which, mechanically, the body acts like an inverted pendulum during each foot’s contact. Each of us has an optimum stride frequency related to the length of our legs – the longer they are, the lower the frequency. Running is less efficient and the motion is more like the compression of a spring than a pendulum’s swing. The movement is characterised by a flight phase when both feet are airborne, followed by one foot making contact with the ground for a mere quarter of a second or so. During this impact, the body experiences forces that are more than double those encountered when standing.…

ANYONE who has attempted an endurance race such as a marathon will have had a silent word with themselves at some point along the route. It can be tough to find the mental strength to keep going when fatigue, boredom, pain and self-doubt kick in. But until recently, scientists concerned with the limits of human endurance performance tended to overlook the mental muscle and focus on the physiological – how the body functions, in other words – and the environmental. Over the past decade, however, they have come to understand that, to a greater extent than ever previously imagined, those limits are determined by the grey lump between your ears. The brain makes the call to slow up or break down long before the lungs and limbs are finished. Understand…

A RECENT review of 61 exercise studies, totalling more than 900 participants, lays out the grim evidence that will be familiar to many. Weight loss often starts off well at the beginning of a new exercise regime, but it fades over time, so that a year or so later, the weight lost is a vanishing fraction of what we would expect from all the calories burned through working out. In one of the longer trials, men and women in the US burned 2000 calories per week during supervised exercise sessions for 16 months. After nine months, the men had lost around 5 kilograms, after which their weight plateaued. Women in the study lost no weight over the entire 16 months. Neither men nor women lost what we would have expected based…

IF ONE of the reasons you signed up for exercise was the thought of guilt-free bowls of pasta, you had better make sure you are working for it. Unless you are planning to go hard for 90 minutes or more, you can step away from the carbonara, the extra fuel isn’t necessary. However, for long workouts, like a big race, it can help. When elite male cyclists doubled their normal carb intake for three days, they increased their power output by 6 per cent and their speed by 1.3 kilometres per hour in a 1-hour time trial that followed a strenuous 2-hour ride. A general guideline is to eat 8 to 12 grams of carbohydrate per kilogram of body weight per 24 hours for 1.5 to two days before long,…

FILTER-FEEDERS aside, humans are the only creatures that can get away with sitting around all day. But there is a huge cost to our sedentary ways, not only to our bodies, but also our minds. Falling IQs and the rise in mental health conditions have both been linked to our lack of physical movement. And the connection between movement and the brain doesn’t stop there. A revolutionary new understanding of the mind body connection is revealing how our thoughts and emotions don’t just happen inside our heads, and that the way we move has a profound influence on how our minds operate. This opens up the possibility of using our bodies as tools to change the way we think and feel. Evidence is starting to stack up that this is…