Life in chairs is at least a little bit hazardous to your general health, above and beyond just a lack of physical fitness. We suspect this today thanks to some good science, from sources like British Journal of Sports Medicine (more on this below). During my decade working as a massage therapist, I learned of the more musculoskeletal dangers of chairs from watching my clients suffer through their desk jobs. It seemed obvious that lots of time in chairs was likely to cause back pain at least.
I was wrong, though, and it became the ultimate example of destroying an “obvious” fact with actual science. This article explores the health effects of a sedentary lifestyle more objectively than I did in my career as a massage therapists, starting with the debunking one of the big myths in musculoskeletal medicine…
What were the bodies like on the beach? Ugly and white and ruined by offices.
Leonard Cohen, The Favourite Game
This section, new in early 2017, corrects a major error, reversing an opinion I promoted for well over a decade. A lot of time spent in chairs may be unhealthy in some ways — much more on this below — but they are not the back torture device I once thought. There’s not much wiggle room on this point: many studies have shown that people who sit a lot simply do not get more back pain than more active people. There is no link. It’s just not a thing.
This was already established as early as 2000 when Hartvigsen et al. looked at thirty-five different relevant experiments,1 14 of them about sitting at work, 21 with otherwise physically “lazy” jobs, and 8 that had “a representative sample, a clear definition of LBP and a clear statistical analysis”:
Regardless of quality, all but one of the studies failed to find a positive association between sitting-while-working and LBP. High quality studies found a marginally negative association for sitting compared to diverse workplace exposures, e.g. standing, driving, lifting bending, and compared to diverse occupations. One low quality study associated sitting in a poor posture with LBP. The extensive recent epidemiological literature does not support the popular opinion that sitting-while-at-work is associated with LBP.
That was published at about the same time that I was still forming my own “professional” opinion that sitting a lot probably causes low back pain.
Seven years and several studies later, Lis et al. reviewed fifteen suitable studies.2 Although they noted evidence of a link between back pain and awkward sitting postures and vibration — so helicopter pilots get a lot of back pain, apparently — they otherwise just confirmed Hartvigsen et al.’s findings, concluding that “sedentary lifestyle by itself is not associated with LBP.” This was then backed up again by two more reviews in 2009,34 which are the most recent as of early 2017, which is when I finally caught up to the evidence, noticed my mistake, and updated this article and others.
How did I go so wrong? Easy enough: I just never checked.5
It remains remotely possible that back pain is more common in certain kinds of “chair warriors.” But if there is any link at all, it cannot possibly be a strong one.
So what’s left? What else could sitting a lot do to a person?
In the science fiction classic, Ringworld, Larry Niven paints a future full of frail, sensitive people. Pain and effort are virtually eliminated, and fitness and pain tolerance along with them. But so what? It’s no great loss, as long as no one has to do any physical work or suffer. Right?
What Niven didn’t know then is just how unhealthy it might be to live a life without effort.
We’re already half way to that future. Everything our great grandparents did was more work. The population of agricultural workers is less than a third what it was fifty years ago, let alone a hundred years ago.6 The most trivial tasks required more physical effort then than now, and most things that are hard work have been automated: transportation, agriculture, manufacturing. The Information Age has created legions of workers who literally only lift their fingers for eight hours every day.
It’s not the longevity lifestyle: a national Geographic article examining three unusually long-lived groups of people found that regular activity was a major common denominator, among other things.7 None of them were programmers. We’re certainly soft.89 Musculoskeletal problems, at least, seem to be steadily on the rise. (That’s hard to prove, but there is evidence.1011)
The basic problem is that biology is a use-it-or-lose-it business. Everything in the human body works on feedback. Nothing works (or heals) without stimulus. Tissue can literally die without stimulation. A bed sore is a rotting patch of stagnant tissue, and it’s a real and serious problem for anyone who actually can’t move. (This is how Christopher Reeve died in 2004: an infected pressure ulcer.) Simply failing to move isn’t much better.
Chair-bound workers are essentially suffering from sub-clinical bed sores: muscles start to howl for the physical and neurological stimulation they need to survive and thrive, but we only move just enough and just in time to stop tissue from actually starting to become necrotic (dead).12 But they certainly get “sick,” especially in the shoulders, back and hips — which tend to remain relatively immobile even when we get up and go to the water cooler.
Everyone knows you’ve got to “use it or lose it,” but what does that mean exactly? What do we lose, and why? And how does using it help?
Research has shown that chronic inactivity causes marked degeneration of virtually every measure of physical fitness,1314 such as relatively obvious problems like the degeneration of reflexes,15 interesting examples like reducing the tendon rot from disuse mentioned above, and — ack! — vulnerability to chronic pain.16
Research like this began a long time ago,17 most of a century18 — a litany of bad news for chair warriors, connecting inactivity to cardiovascular disease, diabetes, and cancer.19202122 Sitting around is even exhausting! True story: you will feel less fatigued if you get regular activity.23
There are probably many mechanisms for all this, but one of the most interesting is that muscle tissue may actually be a wellspring of health-sustaining, regulatory chemicals — like big, beefy glands that you can flex — but they do this mainly when they are working, almost like they need pumping. When resting for too long, muscles cells stop producing these substances that we need for normal biological operations.2425
That’s all pretty grim, but it gets worse: activity may not reverse that effect, or not easily. The effect just described, for instance, was not easily reversed by exercise.26
I sure am! I exercise a lot! But I sit even more. An active couch potato27 describes exercisers who sit most of their day (kind of like a weekend warrior, but the emphasis is different28). It aptly describes nearly everyone who sits at work but is otherwise active.
Despite our activity, active couch potatoes may have the same health risks as entirely inactive ones.
And not only is there a correlation between inactivity and certain kinds of cancer, but it may not be possible to compensate simply by getting more activity when you’re not in the chair. Studying dozens of cancer studies, Schmid et al found that the cancer risk was the same if the chair time was the same, whether subjects were otherwise active or not. “[The results] indicate that the increased risk of cancer seen in individuals with prolonged time spent sedentary is not explained by the mere absence of physical activity in those persons,” the researchers say.
A 2014 experiment put accelerometer’s on a couple thousand people for a while and then checked their aerobic fitness, finding that a couple of hours of sitting was just as harmful as 20 minutes of exercise was beneficial.29 Which suggests that it may be difficult to exercise enough to compensate for sitting all day.
This all seems quite bad. Maybe as bad as … smoking?
It’s a bit like smoking. Smoking is bad for you even if you get lots of exercise. So is sitting too much.
Travis Saunders, quoted in Sitting is the New Smoking — Even for Runners
Indeed, it’s hard not to hear it. This analogy has been everywhere lately (circa 2011-2014), with no clear single origin.30 NBC News made it news. Runner’s World ran with it. Science writer Alex Hutchinson covered it well for The Globe & Mail, but the headline (which Alex didn’t write) trumpets the analogy like it’s The Truth, already well-established.
But sitting is like smoking? Really? Isn’t that just a bit hyperbolic?
Well, yes, of course it is — smoking is exceedingly bad for you; it’s hard to believe sitting is anywhere near as dangerous, probably “only a fifth or a sixth as bad as smoking,” specifically (according to the editors of British Journal of Sports Medicine, and somewhat tongue-in-cheek, I think31). Many people seem to have become annoyed by the analogy, and some bright people scoff at it…with good reason.32
And it’s just an analogy, which serves to suggest two things:
If the second bit is true — if — then we would want to reduce the total chair time to nullify its negative effects … not just try to exercise to compensate for it. Maybe in the future people will marvel at how a few generations of people ruined themselves because they didn’t know better than to sit down all day?
This whole business always seemed fishy to me.33 Here’s a little logical bombshell dropped on the hype: if a lot of time stuck in a chair was actually as perilous as smoking, people with serious movement limitations — especially paraplegics and quadraplegics — would be dropping like flies. (They aren’t.) So, clearly sitting cannot be disastrous for general health.
And now there’s (already) good evidence that there is, in fact, no clear association between a lot of sitting and mortality:34 sitting is probably unhealthy in all kinds of less lethal ways (which is what the rest of this article is about), but it’s not killing anyone — certainly not people who are otherwise doing a decent job of taking care of themselves. Hooray!
So that’s one less thing to be unreasonably concerned about. Which is great. Because if anything actually is “the new smoking,” it’s stress.35
There is a reason that babies all look pretty similar: none of them have been shaped by stress yet. Oh, sure, they have some distinguishing features, but nothing like adults. They are kind of larval looking, all of them.
Much of who you are as an adult is a modified — stress-adapted — version of an original template.36 Most of who you are and what you are physically capable of is the result of adaptation to stresses and stimuli.
All of biology is organized around adaptive reactions to stimuli: immediate reflex (neurological) responses, nearly immediate hormonal and behavioural responses, tissue change responses. Every response is about improving conditions for the organism. Starting to fall down? The organism reacts to stop it. Regular pounding impact on your legs? Make the bones stronger.
Take away the stresses, and the body steadily stops investing energy in unnecessary adaptations. Adapting is “expensive.” You don’t do it if you don’t have to.
The way some tissue adaptations work has been extremely well-described by science. Others, not so much. Bone adaptation is the best understood … and the most surprisingly fluid. Bone adapts well.
There are two “laws” of tissue adaptation, one each for hard and soft tissue. Wolff’s law is that bone will change and strengthen in response to loading. This was first noticed by Julius Wolff in the 19th Century, who got the naming rights. It was greatly refined in the mid 20th century by Dr. Harold Frost, an American surgeon who studied bone biology, and published scientific papers more often than I change my socks. The full details of how bone responds to stress are described in his Mechanostat model. The corollary in soft tissue is the obscure and much less developed Davis’ law. (No one even seems to know who Davis was.)
Although there’s no question soft tissue does adapt to stress, the responses of muscles, tendons, and ligaments are much more complex and less well understood. Many treatments are based on the idea of forcing adaptation or “toughening up” tissues by stressing the tissues. It has always been a reasonable idea, but the devil is in the details: what constitutes the “right” amount and kind of stress is difficult to know, and the results of such therapies have generally been highly inconsistent.
In 2012 and 2013, it seems to have become strangely fashionable to deny the health benefits of running, and to assert that it actually makes you fatter and erodes muscle and bone! For example, these claims were actually made in John Kiefer’s extremely popular article, Why Women Should Not Run (and shredded in this great rebuttal, Sorry, but Science Says Running is Good for You, Not Bad).
Running can be hard on bodies, but it takes mental gymnastics and abuse of the evidence to believe that “cardio above a walk or below a sprint is bad for you (especially if you are a woman).” However, even the assumption that running can be “hard on bodies” is not safe. For instance, the evidence actually shows that “running significantly reduced arthritis and hip replacement risk.”37
Say whaaat? Running is good for joints?
Well, at least not particularly bad for them. The results are probably due in large part to the fact that runners were typically skinnier. Nevertheless, the data flies in the face of the common assumption that running is much harder on the joints. Instead, what it clearly shows is that running is either neutral or helpful …. probably because using joints is healthier than not using them, on average.
Obviously overuse is another matter.
Get more exercise, but don’t go overboard. Although the modern human tends to err on the side of “not enough” exercise, it’s also surprisingly easy to push too hard when you’re unconditioned. “Too much” is surprisingly little for tendons and joints that aren’t used to much. This explains the plague of repetitive strain injuries in weekend warriors
A fascinating 2007 study showed that tendons are harmed by both over and under use.38 Tenocytes (tendon cells) adapt to the forces imparted on them, creating a tissue tolerance “set point” depending on your activity level. This set point can decrease with disuse, and increase with exercise — as long as there’s enough rest. Activity that is too frequent or intense might damage cells without giving them a chance to adapt. Biological proof of “use it or lose it”!
That pretty clearly implies a need for some kind of in between exercise intensity, something not too easy nor too hard: but a Goldilocks “juuuust right.” To avoid hurting yourself, take only baby steps outside your comfort zone — especially at first, and especially with any activity that’s highly repetitive.
I’ll finish with a diagram:
There’s a popular notion that sitting causes real shortening of muscle tissue: that you “freeze like that.” Specifically, the idea is that sitting causes your hip flexors to truly shorten, to cinch up and stay that way, to actually lose extensibility. This is not wrong in itself. For instance, a good quality 2012 study found that high heels cause adaptive shortening of the calf musculature by 13%.39 And here’s an example of the argument being made by a particularly credible and eloquent expert, evolutionary biologist Daniel Lieberman:
Paper after paper, study after study, have shown that chairs give us back problems because they shorten our hip flexors, give us weak backs, of course it make us sedentary. We take years off our lives probably by sitting in chairs, but we like them because they’re comfortable. You go to an African village, you find me a chair with a back. That’s a rare thing out there.
Brains Plus Brawn, by Daniel E Lieberman
Unfortunately, it’s not quite as clear cut as that. Even when muscles do shorten, it doesn’t necessarily mean much. That calf muscle shortening I mentioned above? The authors of that paper also found that it had no measurable effect on ankle function.40 Todd Hargrove of BetterMovement.org explained this very well:
It is well known that completely immobilizing a joint for an extended period of time can lead to loss of muscle sarcomeres and contracture and cross linking of connective tissue. However, it appears that one can fully prevent any negative effects of extended immobilization on tissue length with only short and infrequent bouts of movement. In one study, researchers kept the soleus muscle of a rat completely immobilized in a cast for 10 days. Every two days the cast was removed and the muscle was stretched for fifteen minutes. This was enough to preserve tissue length, but not enough to make the rat happy with the experiment.41
In another study, just half an hour of stretch a day preserved range of motion in a muscle that was immobilized in a shortened position for the rest of the day.42 These studies suggest that sitting in a chair almost all day every day would not cause loss of tissue length, provided you get up to go the refrigerator every once in a while.
So it takes an enormous amount of abuse of your body to have any effect on muscle length, it probably doesn’t matter all that much, and it’s really not that hard to prevent. A lot of sitting is almost certainly problematic,43 … but probably not because of “seizing up.”
No — you do not need a stretching habit, per se, to keep your muscles from shrivelling up. Nearly any movement is sufficient to prevent that (see previous section). Although it’s better than nothing, getting out of the chair to stretch specifically is simply the wrong tool for the job. A little static elongation of muscle tissue just does not constitute adequate stimulation to be an antidote for all the effects of four hours of sitting per day, let alone eight or twelve.
What you need is a similar-but-better concept I call “mobilizations”: repeated, rhythmic elongation and contraction of muscle tissue. For instance, when most people get up from a long sit, they will instinctively stretch their arms backwards, opening up the chest, and a few will then close the chest as well, flexing the same muscles they just stretched.
That’s the perfect thing, the right impulse — you just need to do a bit more of it. Repeat! Doing it once pulls your chest and upper back muscles away from the brink. Doing it ten times in a row a few times a day is mobilizing. Basically: light exercise, emphasizing the range of motion of the joints that need it the most after sitting in a chair.
I have a whole, large article (of course) about mobilizing:
Everything — but, above all, your heart and lungs, and your brains if you want to keep sharp into old age.
The evidence is overwhelming that moderate aerobic activity is probably the single most important kind of exercise … because there isn’t a single cell in your body that doesn’t depend on a constantly blood-borne supply of oxygen and nutrients. The delivery system must be constantly challenged. Aerobic exercise affects the entire system.
But you really have to use anything that you don’t want to lose.
There is a concept in athletics called “training specificity.” It’s one of the Laws of Exercise: you get good at what you do, and only what you do. If you jump up and down on one foot, you’ll get good at jumping up and down on one foot … but not the other foot. If you lift weights slowly, you’ll get good at lifting weights slowly … but not good at lifting them quickly.
You kind of need a specific exercise for anything you want to keep in shape. Which is why so many exercise experts recommend a wide variety of exercises.
The importance of extremely comfy and ergonomically dazzling chairs is exaggerated. There is simply no such thing as a perfect chair: your body isn’t comfortable with any position for hours at a time. The problem isn’t the position that your body is in, but the lack of motion, exertion, and variety of stimulation, and no chair can solve that.
Unless perhaps it keeps you mobile by design…
The best chair might just be two or three simple-but-different chairs used in rotation, including or used in conjunction with an destabilizing cushion, such as a Disc-O-Sit or Sissel Sit, or a fitness ball.
In my office, I have a standard office chair and a stool, both of which I use in combination with a Disc-O-Sit for plenty of variety. Because I have a home office, there are plenty of other places I can sit to work. All of this variety is more important than having one fancy chair.
And, if you still want a good chair, and if you’ve got the cash, by all means — get yourself a fancy chair! I did. I worried about the cost until I sat in it. I’ve now been sitting in it without buyer’s remorse for about 12 years.
Standing to work has been gaining popularity as an answer to the presumed perils of sitting. For instance, according to a business blog, several Japanese companies have ditched desks entirely. Everyone stands to do their office work!
Was it a tough change? Yes. The first month, or even two, is apparently quite difficult as the body adjusts. But then you begin to feel healthier, perhaps lose a few pounds due to the activity resulting from constant balancing, and you realize you are more productive.
After keeping an eye on this trend for the last decade, I have finally decided to (mildly) advise against it. No, you should probably not choose to stand on the job, unless it particularly appeals to you or fits your circumstances unusuall well. Standing seems to be just another form of stagnancy, with its own dangers. The Cornell Human Factors and Ergonomics Research Group (which looks like an interesting resource) identifies a number of problems with standing to work:
Standing to work has long known to be problematic, it is more tiring, it dramatically increases the risks of carotid atherosclerosis (ninefold) because of the additional load on the circulatory system, and it also increases the risks of varicose veins, so standing all day is unhealthy. The performance of many fine motor skills also is less good when people stand rather than sit.
They review a few other problems with sit-stand workstations, and conclude with the advice to mainly sit to work but get up and move regularly:
The key is to build movement variety into the normal workday.”
In other words, regular microbreaking. If you do choose to stand to work — and obviously it does make more sense for some jobs and situations — then here’s quite a decent little article about choosing a desk (from Macworld Magazine, of all places).
Ergonomics “professionals” all over the world are busily working on the wrong thing, trying to get people into good positions so that their workstations are as efficient as possible and require as little movement as possible. The goal of this kind of ergonomics is to turn people into cyborg-like extensions of their cubicles. The goal is also damage control: how to minimize the consequences of an insane amount of sitting, while still actually keeping people in their chairs.
And it’s all a sinister plot, obviously. Modern workplace ergonomics is a classic, Dilbert-esque piece of corporate manipulation. It fails to solve an obvious problem in an obvious way. The obvious problem is sitting, and obvious solution is getting up and moving around regularly — what more progressive ergonomics professionals call “micro-breaking.”
This is not to say that conventional ergonomics is useless or trivial — even if you get up fifty times a day, a bad mouse position is still going to torment you. But let’s get it in perspective!
Microbreaks are regular, small, meaningful breaks from being stuck in one position at work. This dynamic ergonomics concept has begun to eclipse more familiar, conventional ergonomic priorities. The idea is simple: no chair or efficiently arranged computer workstation, no matter how comfortable, can protect you from the danger of hours of sitting every day. The only truly ergonomic workstation “arrangement” is to break free of it regularly. You must have a “come here/go away” relationship with your workstation.
Yes and no. Any kind of getting up is so much better than being glued to your seat that I am always reluctant to criticize it. It really is better than nothing. But it really isn’t enough, either.
The key point that usually gets overlooked is that walking around the office does not — and I know this will come as a big shock — actually give your back muscles all that much to do. Photocopying isn’t really a big musculoskeletal challenge. Going the bathroom isn’t exercise.
Anything is better than nothing, of course. And it’s extremely difficult to judge the right amount — there’s no way to base it on evidence. My recommendations are a compromise between what’s practical and a rough estimate of what’s necessary.
A couple minutes of mobilizing per hour is probably enough of an antidote to the worst consequences of excessive sitting, and it’s a reasonably practical amount — although even just five minutes per hour can be surprisingly hard to fit in. If you can, double the dose to ten minutes per hour — if your work situation allows, and you have the discipline for overdoing this a bit. The high end of this range is inspired by all that “sitting is the new smoking” evidence. It may not be necessary to do that much. Or then again it may. But ten minutes per hour is roughly the most the average person is going to be willing or able to invest in preventative exercise. That’s 16% of your time!
How can a few minutes be enough? Simple: sitting wouldn’t be particularly harmful, except that we do so much of it. It’s probably not too hard to counteract the effects of an hour of sitting with a few well-chosen exercises. If you make a point of flexing and using the muscles that are most needful — efficiency! — it probably doesn’t take much to undo the damage.
Getting up and bending over to touch your toes thirty times every half hour may seem forced, contrived or arbitrary — but it’s the only cure for a forced, contrived and arbitrary amount of sitting.
There’s more about the how-to of microbreaking:
Above all, take the risk seriously. True health and fitness are probably not compatible with serious chair warriorism. If you can’t avoid chairs, most people have to take preventative measures in order to survive their careers.
The best example I know of is a young man, mid-twenties, an extremely fit hockey player, roller blades everywhere — and a hardcore workaholic computer programmer, sixteen hours per day (no joke). His chair time is so physically punishing — and his athletic activities so demanding — that he has found that prevention is an absolute necessity. For him, the problem is unambiguous and the consequences of negligence are immediate: if he isn’t careful to protect his body from all that sitting, he starts to suffer right away.
The same thing is happening to you at eight-hours per day — just not as fast.
I am a science writer, former massage therapist, and I was the assistant editor at ScienceBasedMedicine.org for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.
— Major correction — New section explains my new position, which is the opposite of my old position: “Sitting a lot is not — repeat, not — a risk factor for low back pain.” Read more about the mistake.
— Added “Why is exercise healthy?” sidebar.
This systematic review of 15 studies, 8 classified as high quality, “confirms that sedentary lifestyle by itself is not associated with low back pain.” Only one of the high-quality studies reported a link.BACK TO TEXT
This review of 18 studies of risk factors for low back pain confirmed strong evidence of no link to sitting, standing, walking, or common amateur sports; “conflicting” evidence about leisure activitiues like gardening, whole body vibration, hard physical work, and even “working with ones trunk in a bent and/or twisted position”; and no evidence of any quality about sleeping.BACK TO TEXT
The article examines three long-lived groups of people, and what they all share: non-smoking, family-oriented and social, active daily, and a diet rich in fruits, veggies and whole grains.BACK TO TEXT
An old friend of my family’s has been an outdoorsman for his whole life. He’s one of those people who doesn’t just go camping, he “goes into the bush” for a while. He tells me that he’s seen a trend in his Outward Bound students, even the ones who are superbly gym-fit:
“They’re wimps,” he says. “Pure and simple. Put them on a mountainside, they’re whipped in a few hours, if not a few minutes. I can go for days, forever practically. They ask me, ‘Aren’t you tired yet?’ I never am.”BACK TO TEXT
This is a story a massage client once told me. Maybe it’s exaggerated, but I’ve known quite a few farmers and have no trouble believing it…
An aging farmer fell off a ladder and hurt his back. He refused to be taken to the doctor. “Not necessary,” he insisted. “Haven’t been to a doctor in thirty years, and I ain’t starting now!” But he was too crippled to resist, and his children took him to get help. The doctors soon discovered that he had broken his back — but not for the first time. He had, in fact, fractured his back twice previously, and healed, without ever getting help.
This anecdote strongly suggest that hard-working people are truly tougher — maybe a lot tougher — than us sedentary folk. We may be lot more prone to injuries and complications.BACK TO TEXT
Is body pain getting worse? It seems to be in Spain. Studying health surveys of the population of Spain, researchers looked for changes in rates of serious musculoskeletal pain since the early 90s, finding that it “increased from 1993 to 2001, but remained stable from the last years (2001 to 2006).” They also found that it was more common in women (almost twice as much), the poor, the insomniac, and people with other health problems.BACK TO TEXT
In the northwest region of England, researchers examined then-and-now data try to figure out if people hurt more than they used to, between the 1950s and today. They used data collected by the Arthritis Research Campaign, looking at the prevelence of low back and shoulder pain. Interviews and questionnaires were used. They found that “the prevalence of musculoskeletal pain is much higher than that reported over 40 years ago. The change in prevalence is unlikely to be entirely due to the study design.” They pointed out that the appearance of an increase “could be partly explained by the ‘worried well’. The ‘worried well’ are those patients who are concerned about their health, and attend their GP to seek reassurance about their well-being.”
Their data also contributes to the evidence showing that low back pain dominates the middle of life, and does not increase steadily due into the golden years, as so many people assume.BACK TO TEXT
It sounds like I’m exaggerating, but it’s probably literally true. Bed sores do not take all that long to form. Ask any nurse. They are underway within a couple hours, andpeople who log serious time in chairs are almost certainly flirting with pressure sores — it’s just that they are easily prevented with relatively little movement.
Wikipedia: “A simple example of a mild pressure sore may be experienced by healthy individuals while sitting in the same position for extended periods of time: the dull ache experienced is indicative of impeded blood flow to affected areas. Within 2 hours, this shortage of blood supply, called ischemia, may lead to tissue damage and cell death. The sore will initially start as a red, painful area.”BACK TO TEXT
This article presents data on how healthful mild to moderate exercise is, and connects a lack of exercise with “killers” — obesity and smoking, for instance, are strongly correlated with inactivity.BACK TO TEXT
From the introduction:
Recent, observational studies have suggested that prolonged bouts of sitting time and lack of whole-body muscular movement are strongly associated with obesity, abnormal glucose metabolism, diabetes, metabolic syndrome, cardiovascular disease (CVD) risk and cancer, as well as total mortality independent of moderate to vigorous-intensity physical activity.BACK TO TEXT
Accordingly, a possible new paradigm of inactivity physiology is suggested, separate from the established exercise physiology, that is, molecular and physiological responses to exercise.
This new way of thinking emphasises the distinction between the health consequences of sedentary behaviour, that is, limiting everyday life non-exercise activity and that of not exercising. Until now, the expression “sedentary behaviour” has misleadingly been used as a synonym for not exercising. Sedentary time should be defined as the muscular inactivity rather than the absence of exercise.
From the abstract: “All subjects showed that both short and long latency stretch reflex FMG activities of muscle biceps brachii were reduced immediately after 20 days bed rest, and then recovered gradually to pre-bed rest levels at one- to two-months after bed rest ....” Note, however, that another muscle studied did not show reflex degeneration in the same conditions.BACK TO TEXT
This elaborate test of mice showed that they were less sensitive to certain kinds of pain if they had gotten more exercise. Specifically, regular exercise protected them from pain caused by exercise (no surprise there), but also — a little more interesting — pain caused by injecting carageenan (which causes inflammation). So exercise probably protects mice from the pain of carageenan injections — does that mean it will protect humans from other kinds of pain? We can’t quite go that far based on the this research. Nevertheless, it’s suggestive, and I’m inclined to agree with the authors: “physical inactivity is a risk factor for development of chronic pain and may set the nervous system to respond in an exaggerated way to low-intensity muscle insults.”BACK TO TEXT
From the abstract: “Chronic exercise increased feelings of energy and lessened feelings of fatigue …”BACK TO TEXT
This study is a nice FUD-fighter: its results directly contradict the overhyped notion that a lot of sitting is just as dangerous as smoking, an idea that’s been around for a few years now and it reeks of premature, fear-mongering speculation. There was never any good evidence that “sitting is the new smoking,” but this is good evidence that “sitting time was not associated with all-cause mortality risk” in over 5,000 subjects.
This doesn’t remotely get us off the exercise hook. It doesn’t mean that a sedentary lifestyle is safe or healthy, but it does strongly suggest that we aren’t doomed by it (that is, you likely can compensate for a lot of time in a chair by being as active as possible otherwise).
And it’s still possible that sedentariness is unhealthy independently of other exercise, and I’m sure we’re going to see more research about it. Regardless, the scary headlines over the last few years were not defensible, and this new evidence is definitely reassuring.BACK TO TEXT
“It was found that the connective tissue accumulation that occurs in inactive muscles can be prevented either by passive stretch or by active stimulation.” An important point here is that stretch isn’t doing anything that muscle contraction isn’t, so the evidence does not particularly support a stretching habit.BACK TO TEXT