The Debate Continues over Sitting and Its Effects on Mortality

Do periods of sedentary behavior, in particular sitting, increase the risk of mortality and age-related disease regardless of whether or not there are periods surrounding exercise? The epidemiological research community can take decades and dozens of studies to chew over questions like this. Most recently, evidence was presented to suggest that sitting for longer periods of time is an independent risk factor for mortality even for those who exercise. The study here presents evidence for a more nuanced conclusion, that exercise does compensate for periods of time spent sitting.

This sort of contradictory data is very much par for the course in this area of study: ignore any single set of results, and look for consensus across as many studies as possible. Meanwhile consider whether or not the arrow of causation might point from health and mortality risk to behavior such as sitting and activity; are less active people exhibiting higher mortality because unhealthy people tend to be less active, for all the obvious reasons, for example?

For less active adults, the amount of time spent sitting may be associated with an increased risk of death; however, increasing physical activity to recommended levels may eliminate this association in some. Recent studies have determined that high levels of sedentary behavior are associated with adverse health outcomes. However, the link between sedentary behavior, mortality, and heart disease are not always well understood.

In this study, researchers aimed to determine the association between sedentary behavior and physical activity on mortality and to estimate the effects of replacing sitting with standing, physical activity and sleep. Participants included 149,077 Australian men and women aged 45 years and older who were asked to complete a questionnaire that determined how many hours per day an individual spent sitting, standing and sleeping. They also were questioned about the total time spent walking or participating in moderate or vigorous physical activity.

After a median follow up time of 8.9 years for all-cause mortality and 7.4 years for cardiovascular disease mortality, higher sitting times (more than six hours) were associated with higher all-cause and cardiovascular disease mortality risks, but mostly in those did not meet physical activity recommendations. Meeting even the lowest requirements for physical activity eliminated the association with all-cause mortality risk, with the exception of those who sat the most (more than 8 hours a day). Compared to those who were highly active and sat for less than four hours per day, the risk remained substantially elevated even among physically inactive participants who sat for 4 hours per day only.

While replacing sitting with standing was associated with risk reduction in low sitters, replacing sitting with physical activity was more consistently associated with risk reduction in high sitters. The researchers found that moderate physical activity only reduced cardiovascular disease death risk among high sitters. The largest replacement effects were seen for vigorous physical activity, but this level of activity may not be possible for all adults.

Link: https://www.eurekalert.org/pub_releases/2019-04/acoc-pam041819.php

Comments

"he largest replacement effects were seen for vigorous physical activity, but this level of activity may not be possible for all adults."

Looking around my gym, I'm convinced this is because people >50% are soft and lazy, not wanting to breath hard or break a sweat. It's a social occasion or an opportunity to "fitness signal" for 30% (mostly women, some congregate around a weight machine and think it's a road construction site) ...and these are the people going to Planet Fitness. Of course, I'm aware of being chased by the grim reaper, and many are unaware or ignorant that "Home Base" is maybe ten years away.

Posted by: Tom Schaefer at April 26th, 2019 10:13 AM

I have a problem with this sitting study--it reminds me of the excessive water intake doctors recommended back in the day (8 full glasses a day, maybe more!).

Basically, you are either sitting, standing, or sleeping. I sleep for 8 hours a day, stand in my job about five hours a day, maybe go walking or swimming for an hour, and maybe cook or do housework for an hour. That puts my sitting time at a lethal 9 hours a day--and I have to actively stand up and move around for my job--how many of you older people have jobs like that?

If you don't have to stand for your job, you are likely sitting for an ultra-lethal 14 hours a day. That's pretty much everybody who isn't a traffic cop or soldier on guard duty. And a traffic cop who stands 8 hours a day, goes to the gym for one hour, and does house stuff for an hour STILL SITS FOR a dangerous 6 HOURS A DAY.

The study implies that these unusual, lazy couch potatoes who comprise pretty much everyone on planet Earth are on a headlong sprint to an early grave, while normal people who only sit for 4 hours a day are just barely squeaking by with their slothful inattention to exercise. "Normal people" who sleep for 8 hours, stand at attention at work for 8 hours, and then go for a leisurely four hour jog around the park attain the bare minimum necessary to eke out an extra year or two before they kick off like the rest of us.

I can't believe that most study respondents actually said they are on their feet 12 hours a day, or that the researchers believed these results. I think the study is wrong, and worse, I think it is counterproductive and depressing. People read stuff like this and figure that they cannot possibly measure up to requirements, so why bother exercising at all?

Posted by: Paul at April 27th, 2019 4:49 AM

What about people who are 8 hours sleeping and 16 hours on wheelchair ? Are there studies that shows they die much younger or are more prone to disease than the "normal" population ?

Posted by: Jonathan Weaver at April 27th, 2019 6:06 AM

Hi Jonathan ! Just a 2 cents.

I can't find studies that really explore this is detail... but I will say that any person - Any - person who is in a wheel chair stuck there for life and has to do this 16 hours a day..and then 8 hours asleep in horizontal position will shorten they life because we, as specie, are not made for that. We are made to 'walk'..thus people who lost this ability are seriously disadvantaged, not just for lack of walking/legs...but now it can shorten their lives. Why? Because sedentarity, sitting on and on and never exercising much is death wish and shortens lifespan (you can get stroke, your telomeres will shrinken faster by oversitting; shorter telomeres means shorter lifespan, nearly assured, you may also get more 'Diseases' because of sitting all the time).

With that said, there is 'overdoing it' too..we can't stay up for so many hours...it is ALSO bad/fatal in the lung run...we are suppose to dose between sitting/resting - and staying up for a few hours.

You must take breaks and rest.

Moderation is key between sitting/resting and standing up/walking.

Inversely, sitting for 10+ hours/day can litterally - kill you..age you..so people stuck in wheelchairs..are very disadvantaged..because loss of legs...can't stand up and walk/jog/run.

How do they overcome the handicap? Many paraplegicic poeple in wheel chair do intense 'exercise' and sports (wheelchair sports/paraplegic sports/paralympiades (olympiads/olympics for people that have physical disability)..

we need a few thousands 'steps' each day to keep health, even just a few hundred ones is better that None and sitting for so many hours...that's dangerous, can die of blood clot formation in legs/travel to brain and you age faster, sitting so long. 'walking/standin up' slows aging and activates many pathways that are protective; exercise does the same think (walking/light exercise..to moderate/hard physical bodily exercise in short bursts..not to exhaustion).

Thus people in wheel chair 'compensate' by doing 'wheel chair exercises' and 'traveling with wheel chair'..many wheel chair people develop strong arms..because must 'move themselves + the chair', it's hard/heavy and many have muscled arms...so they do get exercise somehow..
The danger is if they NEVER move around with their chair and 'stay there' in their chair..totally still and 'someones pushes their chair' around..they can't 'move themselves' with the chair...that is very bad..because not only on their sitting on and on..they get no exercise (not moving the chair/themselves and don't do 'wheelchair sports')...and if they eat crap...that's it now diseases will come, nearly assured (especially if they are in 'mid-age' and have become boudn in wheelchair and stuck in it for a few years now..it's like it will go downhill from now because their fitness will be lost...frailty will happen and disease then come; even if you sit/stay still...you Must get Some movement/exercise daily..to Keep fit..and of course, eating healthy helps..if they do CR (and do 0 exercise/0 wheelchair sports)..that, at least, negates some aspect of stuck sitting in wheelchair; but not stop it/diseases comingl just post-pone things).

For anyone stuck in wheelchair for life...they must 'try' to get 'back on their feet' ..even if no more...leg/feet...the figurative meaning of it...not to soud mean or anything...but some paraplegic wheelchair bound people get 'prosthetics' - like 'fake' legs...like war amputees that obtain a fake leg so they can still walk...this way they 'relearn' to walk/never sit too long in their wheelchair; they also Should get Crutches and a 'walker' (a type of device to 'stand up'/to 'lean on' so you can get a balance and stand up/walk with 'walker'...Even if you are wheelchair person, you need to get 'legs' fake ones posed on your lower body so that you can stand up). Whether being wheelchair bound or being a persons Couch Potato sitting in chair all the time...the result is the same, humans are not 'made' for that (our ancestors were standing up/'rose up' from the monkey/on 4 legs position..and then became 'bipeds' 'walking/standing'..and then had to 'hunt' the food..taht means exercise 'running/walking/scavengig/hunting/'moving around'..thus getting exercise daily to Obtain food'
Today, not so much anymore, we sit in desk jobs...we sit at home..sit in car..sit all the time...BAD, very bad in long run..not made for that. Must get up Stand Up go take a walk..make a few steps in your house..you can even buy a 'treadmill' or 'bicycle machine' to stay at home...but still gets Some exercise while staying home if you prefer that and 'like wathcing TV' (you can watch TV - AND - do exercise - at the same time...many do, this way exercise never boring/repetive. With that said, I suggest people to do the exercise outside because, generally speaking, exercise is the kind of thing weer your 'mind drifts off'/'thinks of all your daily problems' While doing the exercise...like a chore...but you can 'Disconnect'., it's important Disconnect when you do a repetitive task like exercice and 'vary' the exercices to not get bored out repeating same moves...'by disconnecting', I mean, Stop thinking about 'your problems in life'...Rather - Focus - on The Exercise - That's it - That's all...you know..just like taking a shower...there are two ways to take a shower:
- Connected or Disconnected. Connected : ''I think of my problems while taking my shower - every time''. Disconnected : ''I never think of my problems while taking m shower - every time - I Always Think of the Shower itself - I think about the 'water'...dripping on my body/the 'sensation' of the shower/water..it's ridiculous..but I'm enjoying it..and I 'forget my worries' because I 'disconnect').

Just a 2 cents.

Posted by: CANanonymity at April 28th, 2019 1:01 PM

PS:I meant of course.. that 'if it is a possibility' (to obtain prosthetics) fake leg' if you are wheelchair bound..it it is not possible at all... because lost entire legs and can't put fake legs at bottom of torso...then..CR/wheelchair exercise(sports/lift weights with your arms...sitting in your chair)/moving your chair(not have someone push your chair/you)/keeping a social life/occupied is the answer to mitigate the disability.

Posted by: CANanonymity at April 28th, 2019 1:17 PM

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