What’s worse for health? Consistently high sitting time or increased sitting time over 11 years?

Little is known about how changes in sitting levels over time affect health risks and outcomes later in life. In a recent study published in the International Journal of Behavioral Nutrition and Physical Activity, researchers from Australia and Norway set out to examine whether patterns of sitting measured over 11 years are associated with premature death from cardio-metabolic diseases or from all causes.

Several studies have found associations between time spent sitting and premature death.

Research about sedentary behavior and its associations with health, such as too much sitting as opposed to not enough physical activity, have often focused on a single point. In recent years, several studies have found associations between time spent sitting and premature death, and it seems the link persists even after accounting for other physical activity or exercise.

In a new study published in the International Journal of Behavioral Nutrition and Physical Activity, researchers used data from 25,651 adults aged at least 20 years, collected by the Norwegian Nord-Trøndelag Health Study in 1995-1997 (HUNT2) and 2006-2008 (HUNT3). They grouped respondents’ self-reported total sitting time into four categories:

  1. ‘Consistently low sitting’ (low at HUNT2/ low at HUNT3);
  2. ‘Increased sitting’ (low at HUNT2/high at HUNT3);
  3. ‘Reduced sitting’ (high at HUNT2/low at HUNT3; and
  4. ‘Consistently high sitting’ (high at HUNT2 /high at HUNT3).

Over the 11 years, the adults in this population mostly reported that they sat less than eight hours per day, and had a stable sitting pattern during this time. Compared to adults in the ‘consistently low sitting’ group, those with ‘increased sitting’ over 11 years had 51% higher risk of dying prematurely from all causes and 85% higher risk of dying from a cardio-metabolic disease. These rates are higher than for ‘consistently high sitters’, who showed an increased risk of 25% for all-cause mortality and 49% for death from a cardio-metabolic disease.

Adults who were in the ‘reduced sitting’ group were no different in risk for premature death than those in the ‘consistently low sitting’ group. The research team also found certain life events could be attributed to a change in sitting patterns, such as change in jobs, retiring or changes to health.

So what?

Investigating patterns of sitting over time . . . could be a more realistic reflection of exposure to prolonged sitting.

This study shows that sitting habits can be stable over the long term, but in some groups of people, such as those who change jobs, retire or become ill; their sitting patterns may lead to different risks. Investigating patterns of sitting over time adds to previous research focused on a single time point and could be a more realistic reflection of exposure to prolonged sitting especially among people who experience changes in their health or lifestyle.

The researchers propose that future analyses could examine the joint effects of sitting with physical activity patterns over multiple time points and explore the potentially divergent health effects in population subgroups.

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