I recently heard this line in an episode of popular American sitcom Modern Family, “sitting is the new smoking”. It was an off hand comment but during the pandemic, lockdown and general office-style working, sitting has risen exponentially. What evidence is there that sitting is bad for our health?
I don’t know about you, but no matter how hard I’ve tried through lockdown to get in some daily exercise, my time sitting has definitely increased (and made me realise we need a new sofa…). Working from home where everything is at your fingertips, and when Netflix brings out series like Tiger King, it’s hard to not spend a considerable amount of time sitting down. However, over the years numerous studies have shown that extended periods of sitting down are linked to obesity, higher blood pressure and abnormal cholesterol levels, eventually leading to premature death from stroke, cardiovascular disease and certain types of cancer. So does a bit of exercise everyday cut it, or should we be scrapping sitting as much as possible?
Some companies have tried to work around the sitting epidemic by introducing standing desks, and whilst standing will burn 9 calories more per hour than sitting, it still isn’t the answer to our problems. Movement is key. Getting up every 20-30 mins for a quick walk around the house or garden (if you’re lucky enough to have one…) can get your muscles moving and the blood flowing. Some may be thinking “I exercise regularly, surely I’m fine”. Whilst some studies have shown that to reduce your mortality rate by 14% you would need to do 300 mins (5 hrs) of moderate exercise a week, others suggest it is the type of sitting which is an issue. One study found that those who spent four or more hours watching television per day had a 50% higher risk of heart issues and death, compared to those watching two hours or less per day.
Why are chairs so bad for us though? Research from a 2012 paper in The Lancet by epidemiologsit I-Min Lee at Harvard University showed sitting was a common culprit linked to mortality in heart disease, diabetes and cancer cases, killing more than 5 million people a year. Some believe that upon the invention of the chair we became lazy, and whilst that may be true, it doesn’t explain why those who still live in hunter-gather tribes who spend, on average, the same time resting as their office-working counterparts, don’t get resting related illnesses. Amongst different research undertaken was a study by NASA, who were concerned about the effects of long space flight without movement for their astronauts. Participants were involved with their “bed-rest” studies, whereby the volunteers would lie down for long periods of time (in some cases this was months!). As expected, their bones thinned and muscles weakened, but surprisingly another effect was observed: the subjects had higher levels of fats (triglycerides) in their blood. When we walk about and move, our muscles are engaged in our legs and core to keep us upright, but when we sit or lie down, these muscles are relaxed (switched off). When our muscles are working (switched on) they need energy which comes from an enzyme that breaks down the triglycerides in our blood into fatty acids which the muscles can burn for fuel. When we rest for long periods and our muscles are not engaged, triglyceride levels build up and alter the walls of our blood vessels, making them stiffer and more prone to heart disease.
Luckily, research shows it is relatively easy to reverse the effects of triglyceride build up by engaging and using your muscles regularly (every 20-30 mins as mentioned before). We have had chairs for a relatively short amount of time, with them first documented around 5000 years ago. However, in societies with little furniture, resting often involves squatting or kneeling, which palaeoanthrapologists (pale-e-o-anthra-pologists) have found evidence of in our ancestors dating back nearly 2 million years to the Homo erectus. When in a deep squat, the foot is flexed upward toward the shin which presses a small bone in the ankle (the talus) into the end of the shin bone. If this is a regular position, a mark will be left in the squatters shin (a squatting facet). In western culture we have mostly lost the ability to do this. Children have the flexibility, but unless done regularly (or you dance and have loose achilles like me), the ability will be lost as flexibility is lost with age (feel free to give it a go, feet flat on the floor like the image below). What does this have to do with triglycerides? A deep squat or kneel requires the individual to maintain some muscle activity to balance, breaking down triglycerides. Researcher and professor of evolutionary biology at Duke University, Herman Pontzer, suggests that rather than resting less, maybe we need to alter the positions in which we rest.
Much more research is needed to conclusively say how much exercise vs. rest a person needs in order to reduce their risk and also further work investigating the type of rest. Some studies have even shown an increase in “brain power” when you stand vs. when you sit as more oxygen can get to the brain through improved blood flow and sitting could also thin areas of the brain. Many factors will effect each individual, from diet to DNA, but I will certainly be taking more regular breaks to stretch my legs, get those muscles moving, and maybe even squat while watching Netflix. Take a look at the NHS website for more information about sitting and advice on getting more active.