Is sitting time killing us?

Lot's of headlines over the past few years about the idea that the more we sit, the sicker we'll get and the closer to death we'll be.

I've got a bit of a problem with this.

It's true; lots of research has found that the more time we sit doing nothing, the greater risk we are at of dying, even if we're otherwise physically active and fit outside of our sitting time.

However, there is hardly scientific consensus that short or moderate sitting time is hard-core bad for our health if we're otherwise physically fit and a healthy weight.

I looked at how much time I spend sitting each week compared to exercising.  I spend more time sitting.  I don't sit for 4, 5, or 10 hours at time.  I rarely sit for more than 45 minutes straight; but I sit more than I train.

Yet I continue to make gains in the gym, I get better at riding my bike.  My blood pressure is very healthy, cholesterol is about as low as it can get in the healthy range. I would prefer to have more time to be active, and would be better off for it, however, after a decade of having more sit time in my daily work, I have no health issues that would relate to sitting time.

Of course there is no way my personal experience can be a useful reference for a population.  What I'm trying to do is tone down the 'world coming to an end' message that is being touted in regards to sitting time being unhealthy. It's far less healthy to sit all day compared to being active, don't get me wrong.  But you're not going to die next week because you sat too long this week.

Take a look at conclusions from these studies:

Association between various sedentary behaviours and all-cause, cardiovascular disease and cancer mortality: the Multiethnic Cohort Study. 2013

Conclusion:  Leisure time spent sitting, particularly watching television, may increase overall and cardiovascular mortality. Sitting at work or during transportation was not related to mortality.
  
Desk-based occupational sitting patterns: weight-related health outcomes 2013

Conclusion: High levels of desk-based sitting time were associated with an increased likelihood of negative weight-related health outcomes, whereas frequency of getting up from sitting at the desk was not.

 Physical Activity and Screen Time in Metabolically Healthy Obese Phenotypes in Adolescents and Adults. 2013

This study showed that physical activity, but not sitting time, explained why overweight people with fewer health issues had fewer health issues compared to other overweight people with health issues.  So both groups sat about the same amount of sitting time, but those who were more physically active outside of sitting time developed fewer health problems.

Are Sitting Occupations Associated with Increased All-Cause, Cancer, and Cardiovascular Disease Mortality Risk? A Pooled Analysis of Seven British Population Cohorts. 2013

Conclusion: Sitting occupations are linked to increased risk for all-cause and cancer mortality in women only, but no such associations exist for cardiovascular mortality in men or women.

Sitting time and cardiometabolic risk in US adults: associations by sex, race, socioeconomic status and activity level. 2013

Conclusion: Self-reported sitting time was associated with adverse cardiometabolic risk factors consistently across sex and race groups in a representative US sample, independent of other risk factors. Excessive sitting warrants a public health concern.

What's the take-home from all this?

As you can see, some of the studies show no significant health issues related to sitting.  Some show that risks are higher for woman, some show risk for everyone, even if you're physically active outside sitting time. Other studies I've read showed that more physical activity reduces all cause mortality; this is what we're used to seeing.  This remains true, but sit time may reduce the total health effects of otherwise healthy living, especially for woman.

Daily physical activity is really important for our health, too much sitting can be unhealthy, but it's not like living healthy is completely undone by merely sitting.

The bone density, muscle strength, cardiovascular fitness, and flexibility we gain from an active lifestyle outside our work time does benefit us so don't feel like because your job involves sitting you might as well give up.

I'm not saying ignore this new and somewhat unclear understanding of the adverse health effects of sitting too long, I'm saying pay attention to it, but don't fall for the hyped headlines.

Avoid sitting for prolonged periods.  From the research that has been done, it seems like sitting more than 5 to 10 hours a day is the worst.. A lot of this will be because if you sit that long, there is very little time left in the day to be active, and it would be very easy to overeat because total caloric expenditure for the day will be quite low when you sit all day compared to being active.

Some research is indicating that prolonged sitting may contribute to insulin resistance, but other studies show that sitting time for normal weight fit people does not contribute to insulin resistance.

For your overall health, I would be more interested in reducing body fat if overweight, changing what you eat, how much you exercise overall, and working on the behavior changes that allow you to feel passionate about making healthy choices.

For the sitting thing.. it makes sense to avoid sitting for long periods.  Get up and walk around, stretch for a few minutes, change what you're doing for a few minutes every 15 to 45 minutes.  Studies show workplace efficiency, cognition levels, and ability to focus, are all increased by taking frequent short breaks from your main task.

Be concerned with how much you sit.  Be more concerned with how much you eat, and how much exercise (including vigorous exercise) you get.