ARGHH." The first time it happens it takes you by surprise. Was that me? Then it happens again, and again. You give a tiny groan every time you get off the sofa. You hold the bottom of your spine and stretch, wondering if you should see a doctor.
Surely you are too young to have a bad back.
That tends to be the start for a lot of us. Backache is an extraordinarily common burden, with one in four adults experiencing it right now, and 90 per cent of people having back pain at least once in their life. Last year, a series of papers in The Lancet revealed the extent of the problem: back pain is a leading cause of disability around the world. In the US alone it costs an eye-watering $635 billion a year in medical bills and loss of productivity.
Much of the blame has fallen on our increasingly desk-bound lifestyles and growing lifespans, which mean more years of wear and tear on our spines. But these factors only partly explain how we got here and what makes some people more vulnerable or resilient. The World Health Organization expects back pain problems to steadily rise in the years ahead and to affect more people around the globe. That makes it especially worrying that the people who are trying to help are making the problem worse.
The good news is we already have the knowledge to improve things - if we finally apply it. At the same time, new understanding of how and why our brains create the experience of pain is changing the way we think about those crippling aches and pointing to some surprising solutions.
To understand the solutions, we must first travel back 7 million years, to when our ancestors caused the problem. In exchange for walking upright, we got back pain. At least, that is the hypothesis posited by Kimberly Plomp at the University of Liverpool, UK, and her colleagues.
To find out why humans experience more spinal disease than non-human primates, Plomp's team studied the shape of human, chimpanzee and orangutan vertebrae, the bones that make up your spine. They were looking for small bulges called Schmorl's nodes that can occur in the soft tissues between vertebrae and are linked to back pain.
People who had these nodes had vertebrae that were more similar in shape to those of chimpanzees. "We started to walk on two feet relatively quickly in evolutionary terms," says Plomp.
"Perhaps some individuals with vertebrae that are more on the ancestral end of normal human variation are less well adapted to withstanding the pressures placed on the bipedal spine." This ancestral vertebral shape then plagued us throughout our history because it didn't affect our ability to reproduce, so evolution didn't select against it.
Helen Thomson is the author of Unthinkable.
"People say they can tell you what is wrong from a scan. They can't. It's not possible"
Yet despite its long evolutionary history, it is only in the past few decades that we have started to see an epidemic of chronic back pain.
There is evidence that the rise of office culture plays a part. Several studies have found a link between spending more time sitting on the job and increased reports of lower back pain.
Slumping in front of computer screens puts pressure on the muscles, ligaments and discs that support the spine and can deactivate muscles that promote good posture.
Of course, backache can also be caused by accidents, sports injuries or a congenital disorder, but it is lifestyle factors such as obesity and smoking that are the real problem, says Rachelle Buchbinder at Monash University in Victoria, Australia, one author of The Lancet series.
Smoking probably puts people at higher risk of lower back pain because it is associated with a clogging of the arteries, which can damage the blood vessels that supply the spine, leading to muscle and bone degeneration.
Being overweight amplifies the mechanical strain on the back and decreases mobility, predisposing people to deterioration of discs in the spine. Obesity can also increase the production of inflammatory chemicals associated with pain.
Unfortunately, identifying which of these problems has led to your own back pain is incredibly difficult.
According to one study in the US, nearly a quarter of all primary care appointments for adults are for back pain.
Less than 1 per cent of people who seek help will have something seriously wrong, such as an infection, inflammatory arthritis, cancer or a fracture, says Buchbinder.
These people will usually have other red flags, such as fever, rapid weight loss or problems going to the toilet. Everyone else falls under the category of "non-specific back pain", which usually improves in a matter of days or weeks.
Yet many people and their doctors pursue MRI scans in the belief that they will provide an accurate diagnosis, and therefore quicker recovery.
The trouble is, "by the time we're 50, many of us will have abnormalities in our spine: degeneration of the discs, bulging, a little arthritis in the joints", says Buchbinder.
"Some of these may cause pain in some people but not others.
There are lots of people that say that they can tell you what is wrong from a scan, but they can't. It's just not possible."
Getting a scan may not only be a waste of time and money, says Buchbinder, but it can actually worsen your back pain. Once you start to look for abnormalities, you will find them. Once that happens, doctors are more likely to prescribe painkillers, steroid injections or surgery, which maybe unnecessary, ineffective and sometimes harmful.
In 2003, Jeffrey Jarvik at the University of Washington in Seattle and his colleagues randomly assigned 380 people with lower back pain to have an X-ray, which can identify things like fractures, or an MRI scan, which is used to look at soft tissues. A year later, there was no difference in their health outcomes, but those who had an MRI were more likely to have had surgery, exposing them to the risk of infection and other complications.
"The potential for harm has been shown in many studies," says Buchbinder. In countries like the UK, where doctors are advised against offering surgery for back pain, people are often offered anti-inflammatory steroid injections, but these have been shown to be no more effective than placebo. They can also cause increased appetite, mood changes and difficulty sleeping.
Moreover, many doctors, particularly in the US, prescribe stronger painkillers than are necessary, says Buchbinder, fuelling the opioid crisis that has decreased life expectancy in the US. Backache is the number one reason for prescribing opioids, says Tamar Pincus, a health psychologist at Royal Holloway, University of London, despite several studies showing that safer treatments, such as non-steroidal anti-inflammatories, may offer similar relief.
Not all back pain is bad.
The initial pain we get from an injury alerts us to a problem and protects us from further damage. This mechanism can be critical to our survival. But chronic pain that lasts weeks, months or years after an injury has healed serves no useful purpose and can seriously harm our health.
Most people assume that pain must always have a physical cause - an injured muscle or squashed disc, perhaps. Yet often there is no identifiable mechanical explanation. That is why many specialists instead focus on how and why we perceive pain. Fundamental to this idea is our understanding that pain is generated by the brain.
Although we have cells in our body that send messages to the brain to alert us to potentially damaging stimuli, like heat, or a sharp object pressing against the skin, it isn't necessary to stimulate these cells to feel pain, nor is their activity always directly related to our experience of discomfort.
Change Your Life
"Low mood and pain-related guilt increase the risk of pain becoming chronic"
Irene Tracey, a clinical neuroscientist at the University of Oxford, was fundamental in uncovering these nuances. In the 1990s, her team showed that anticipation of pain made networks in the brain light up with activity, and that different aspects of our experience - the intensity of pain or anxiety caused by it - are controlled by separate brain circuits.
All these circuits can be triggered or suppressed. For instance, people who are depressed show greater activity in pain areas, but this can be subdued by listening to music or watching a gripping film. One experiment even showed that religious faith could have analgesic properties in the brain. When devout Catholics were shown pictures of the Virgin Mary while given a sharp pain, they rated their pain lower than atheists shown the same image. When both groups were shown a non-religious painting, their pain rating didn't differ.
Scans showed that the religious iconography triggered a brain area in the Catholic group called the right ventrolateral prefrontal cortex, which inhibits pain circuits.
With chronic back pain, understanding how the experience of pain can be manipulated by the mind is important to figuring out why it sticks around after an injury has healed - and what we can do to prevent this. Pincus points out, for instance, that low mood and pain-related guilt increase the risk of pain becoming chronic. "People start to feel guilty for dropping out of activities," she says. "They then worry that people are going to judge them for that, so they don't accept the activities in the first place."
After several bouts of back pain, people also start to process the world differently, says Pincus. Their pain becomes embedded within their "self-schema": the things they associate with themselves. If they are shown an image of a staircase, for instance, their first thought is, "I can't climb it".
"After a while, you see and feel things coated with pain," says Pincus. "You no longer need the injury to feel pain. And you might experience more intense pain, purely because you're expecting it."
So between our brain and the rest of our body, what can we do to avoid or diminish chronic back pain? First, you may want to rethink your back belt, shoe insoles and any other ergonomic products, since there is almost no evidence that they are effective.
Once they are out of the way, it is time to get up and go. Despite doctors all over the world still prescribing bed rest, it is one of the worst things you can do. When young healthy male volunteers spent eight weeks in bed, their lumbar multifidus muscles, which keep our lower vertebrae in place, had wasted and become inactive.
Some of the volunteers' muscles had still not recovered six months later.
"Many low-back-pain patients have a strong fear of moving," says Luana Colloca, a pain specialist at the University of Maryland School of Nursing. Yet exercise can make all the difference. A study published in June found that exercises designed to strengthen the lower back help ease pain, and just walking regularly helps too. "We need to remove this fear and persuade ourselves to exercise," says Colloca.
Small changes in how we work can also help. People with chronic back pain who used a standing work station for three months saw a significant decrease in the worst pain they felt, and their general pain at the end of the study.
If chronic back pain is already plaguing you, give some thought to your mind. "It's no good asking someone to stop thinking about their pain," says Pincus. "It's like telling someone not to think of a white elephant." Instead we should concentrate on reframing the world so that the things you like doing don't lead your thoughts back to pain. For instance, Pincus herself experiences chronic pain after a knee injury, but says that when it hurts when she is out with her children, she feels happy, rather than sad.
"I feel fantastic. I think: 'You're an amazing mum because you're out walking with your kids.' How we think about our pain may not affect the pain intensity, but it does affect the ability of that pain to infiltrate our daily lives, which creates that negative cycle that can destroy our lives."
Back me up
Clinicians also need to do their bit, says Pincus. When we are injured, our friends say: "Ooh, that must hurt." They acknowledge our pain. Doctors often forget to do so, and that matters. In one study, 50 people were asked to hold a bucket of sand with a straight arm for as long as they could, while listening to a distressing sound.
It is a surprisingly painful task. Immediately after, they were asked to perform tests in which they had to recall lists of words. They then chatted to an examiner who either validated or invalidated their pain, before recalling as many words from the original tests as possible.
Most participants told the examiner that they found the task difficult, that it hurt their arm and that they were disappointed that they couldn't hold the bucket for longer. In the validation group, the experimenter replied: "That's a really common response, many people feel surprised over the level of pain that the task brings about.
When something looks easier than it is, it's often hard to live up to one's own expectation." In the other group, the experimenter would say: "That's strange. Nobody else described their experience this way. No wonder you're disappointed."
People whose painful experience was dismissed remembered fewer words on average and three times as many words that weren't there, compared with the group whose pain had been acknowledged. "Until you get validation of your pain, your brain's resources are completely swept up with how to communicate your suffering," says Pincus. "Doctors need to acknowledge this. If patients are able to be heard, they can understand."
The best way to prevent long-term disability from back pain is to ditch the drugs and promote wider international adoption of a mix of increasing physical activity plus mental retraining, suggest Buchbinder and her colleagues. There is reason to hope that plan will work.
In the Australian state of Victoria, workers' compensation claims for back pain tripled in the early 1990s. Then in 1997, a statewide public health campaign encouraged people to avoid bed rest and unnecessary scans. It also gave them tips on how to think about pain and its impact on their life.
By the time the campaign was over, there was a significant drop in the number of claims for compensation for back pain, compared with a nearby state, which saw no change.
For backache, that may truly be the best advice, says Buchbinder. Perhaps we need to start thinking about bouts of back pain the way we think about other common ailments, says Pincus.
"Nobody expects to get through life without a cold," she says, "and they don't visit the doctor when they do."