Sitting comfortably? You won't be after reading this: Cankles, constipation and even 'brain fog' - why we should all try to spend a lot less time on our bottoms

With many of us chained to a desk for hours a day before heading home to slump in front of the telly, we're spending much of our time on our bottoms.



And it's having an impact on our health, a growing body of evidence suggests.



Last month, for instance, it emerged that spending an extra hour sitting a day (for 13, rather than 12, hours) is linked to a 50 per cent greater risk of being disabled. And this was regardless of whether the participants - all over 60 - also did moderate exercise, according to the U.S. study published in the Journal of Physical Activity & Health.



Spending much of our time on our bottoms is having an impact on our health, evidence suggests

Previous research has suggested spending too much time on our rear may be a new risk factor for illness and even death.



Here, the experts reveal what happens to our bodies when we sit for long periods...

LEAKY VEINS

That dreaded 'cankle' look isn't just unsightly - it may also be a sign that you need to get up.



'If you don't keep blood pumping out of your leg and back to your heart, you get high pressure all the time in the veins in the lower legs and feet,' explains Professor Mark Whiteley, consultant vascular surgeon at the Whiteley Clinic in West London.

'With the vein walls under pressure, some proteins and fluid may leak into the tissues, resulting in inflammation. You often see people who spend a long time at their desk with ridges on their skin from their socks. It's because they're not moving enough.'



This can also apply to slim people, as it is fluid, rather than fat, that causes ridges. Over time, the same problem can lead to brown stains and hardening on the skin, eventually leading to leg ulcers, says Professor Whiteley.

Wiggling your toes can help blood flow

Reduced circulation in the legs can also raise the risk of blood clots, such as deep vein thrombosis (DVT). But most patients have other risk factors, too, such as age.

Wiggling your toes, getting up and walking every 20 minutes, or using an electric circulation booster - which administers small electric shocks to the feet - can help blood flow, says Professor Whiteley.



Those sitting for long periods may also want to wear flight socks.



RAISED BLOOD SUGAR

Sitting for too long can cause us to become insulin resistant, a precursor to type 2 diabetes, says Mark Vanderpump, honorary senior lecturer in diabetes and endocrinology at the Royal Free London NHS Foundation Trust.



Insulin is the hormone that mops up glucose - sugar - from the bloodstream. Along with the liver, muscles are an important sink for storing this sugar.



'When glucose hits the cells, a series of chain reactions take place, allowing it to get inside them. This ease of transfer is known as insulin sensitivity,' says Dr Vanderpump.

'When you're not moving, your muscles become less adept at taking up glucose from the bloodstream and more insulin-resistant. Small, regular movements will improve insulin action at muscle level.'

Just one day of prolonged sitting can lead to a decline in insulin response, according to a study three years ago from the University of Massachusetts Amherst. But just spending time standing up - using a standing desk at work, for example - can get your muscles working, explains Mike Trenell, professor of movement and metabolism at Newcastle University.



'To stay upright you have to engage the postural muscles, a big muscle mass that includes the abdominals, calves and quadriceps - the more muscles you can use the better.'

SLUGGISH BOWELS

Being immobile can make you constipated, says Anton Emmanuel, consultant gastroenterologist at University College Hospital, London.



'When you sit down a lot you have fewer "migrating" contractions - big contractions that push along the contents of the gut. Your bowel content becomes dry and stools get harder. It can happen within 24 hours of being very sedentary or bed-bound.'



Although exercise isn't a cure for constipation, you can reduce this risk by doing ten minutes of low-impact exercise a day - such as using the stairs at work.



Being sedentary can lead to heartburn. 'If you don't move after eating, your stomach empties more slowly and in turn more acid is produced to digest the food. That combination can give you symptoms such as a burning sensation behind the breastbone and food repeating in the mouth.'



Avoid drinking too much while eating, as it slows down the process, and take a quick walk after a meal, he says.



Being immobile can make you constipated, says Anton Emmanuel, consultant gastroenterologist

HEADACHES

'When you're hunched in a C‑shape at your desk, you have to kink your neck backwards to look at the screen. This can affect the nerves in the neck, which can give you a headache,' says chartered physiotherapist Sammy Margo.

The nerves in the forehead and face are relayed through the same part of the brain as nerves at the back of the head, so they can influence each other, adds Andy Dowson, director of headache services at King's College Hospital, London. 'If you have a dodgy neck, it gives you more headaches.'

'When you're hunched in a C‑shape at your desk, you have to kink your neck backwards to look at the screen. This can affect the nerves in the neck, which can give you a headache'

A slumped posture also affects your shoulders, says Sammy Margo: 'Sitting hunched, with the shoulders forward, compresses the shoulder joint, so we're seeing more problems such as shoulder pain, frozen shoulder and loss of movement range there.'



For a better sitting posture, she advises pushing your bottom into the back of the chair to be more upright, or using a Sitfit (an air-filled cushion you put on top of the seat) to help engage the abdominal muscles and pelvic floor.



'For your middle and upper back, stand up once an hour and interlink your fingers behind your back - this reverses the C-shape, helping the neck, back and shoulders.'

CREAKY KNEES

You might assume that knee osteoarthritis is more likely in people who put their bodies through tough exercise routines. But experts say there is also a link with sitting too much. Inactivity can lead to obesity, and increased body mass means more pressure on joints. But another possible link is weakened muscles through lack of use.



Philip Conaghan, professor of musculoskeletal medicine at the University of Leeds, and a medical adviser to Arthritis Care, explains: 'If you're having to push yourself out of your chair with your hands, it's a sign that your quadriceps - the big thigh muscles - are getting weak.



'Some believe muscle weakness can lead to osteoarthritis because strong muscles can take the pressure off the joints.'

Osteoarthritis is particularly common in the knee, he adds.

Sammy Margo says physiotherapists are seeing an upsurge in knee problems due to sedentary jobs: 'Our knees are not designed to be bent at this angle all day.'

BRAIN FOG

Several studies have found a link between physical activity and cognitive function. Professor Trenell explains: 'Any benefits of moving that you see in muscles you should see in the brain. If you have good blood flow to the muscles, you have good blood flow to the brain and it will work better.'

If you have good blood flow to the muscles, you have good blood flow to the brain and it will work better

COLON CANCER

Scientists from the University of Western Australia found that people who spent more than ten years in sedentary jobs were nearly twice as likely to have developed a tumour in the distal colon - an area of the lower bowel - and 44 per cent more likely to have rectum cancer.



This held true whether or not they were physically active in their spare time.



Other studies have linked sitting to an increased risk of breast and endometrial cancers.



One theory is that too much insulin - a potential by-product of being sedentary - encourages cell growth. Professor Trenell says: 'If you're insulin-resistant you have high levels of this hormone circulating around the body. Insulin is a powerful growth factor.'

SLIPPED DISCS

If you don't move your spine, it can become less flexible and more prone to damage from everyday activities, such as tying shoelaces.

'The discs between the vertebrae are squishy, but if you're sitting all day the weight of the vertebrae above can cause the liquid part of them to get squashed out temporarily,' says Scarlett McNally, consultant orthopaedic surgeon at Eastbourne Hospital.



'As the disc is no longer in its protective liquid, sudden movements can make it more likely to become slipped, or suffer wear and tear, causing pain and stiffness,'



We don't help the problem by searching for ever-more comfortable chairs to ease our seating-related aches and pains, adds Laurence Clift, an ergonomist at Loughborough University.

'We say the best posture is the next posture - in other words, you should keep moving.



Physiologically, we're not designed to sit.'



He says the best type of seat is one that 'encourages you to develop self-supporting physiology', such as a Swiss ball or horse saddle-type chair.

How couch potatoes can reduce their risk of a heart attack

The link between physical activity and heart health has long been known.



In the Forties and Fifties, the British epidemiologist Jerry Morris studied the heart attack rates of hundreds of bus drivers - who sat for 90 per cent of their shifts - and bus conductors, who climbed 600 stairs a day. Dr Morris found that the conductors had less than half the heart attack rate of their sedentary colleagues.



Sitting down for too long has been linked to raised blood pressure and raised cholesterol levels, which both increase heart attack risk. Keeping active also keeps your arteries healthy, says Professor Whiteley. 'Exercise makes the heart pound, which makes blood flow faster through the arteries,' he explains.



'The faster it flows, the more nitric oxide you secrete from the inner layer of the artery lining, and that keeps the arteries soft and healthy.



'If you're sedentary and keeping the heart rate to a minimum all day, there's a bigger lateral pressure in the arteries, which pushes fat into artery walls and causes them to harden. That can raise your heart attack risk.'

