The danger of sitting too long

Did you know that 5 MILLION people die each year because of physical INACTIVITY? (1)

Current recommendations are 75-150 min cardio and 2 weight training sessions per week. How can we help people get there? Before we dive into it, there are two terms that you need to be clear about:

  1. Physical inactivity: means moving less than what is recommended. This can be as part of your day (NEAT) or scheduled (exercise).
  2. Sedentary behavior: the act of temporarily sitting/standing still. Thus you can be physically active (i.e. moving more than 30 min/day) but still be a couch potato (sitting >8 hours per day) .

What matters most?

Which matters most: physical inactivity or sedentary behavior? Most studies only measure one, but Ekelund et al combined data from 16 studies measuring BOTH on over 1 million healthy people followed for years. Results show that sedentary behavior (sitting more) is associated with early death, but being physically active reduced this risk. In fact, for people with 60-75 minutes of moderate physical activity (brisk walk/cycling) per day, sitting as long as 8+ hours per day DIDN’T affect their risk of early death.

Sitting > 4 hours?

People with 5-65 minutes of daily physical activity all benefited from sitting less than 4 hours per day, with the most benefits seen in the least active groups. Remember though, this is an observational study looking at REPORTED data i.e. people answered questionnaires on their physical activity level and physical activity wasn’t actually measured. The study is in fact looking at group differences between people who SAY they sit a lot and people who SAY they move a lot. The inactive group might for instance also smoke more, meaning that other behavioral differences besides the sitting and activity can explain the differences in risk of early death between groups.

Data presented in the study

Observational data has flaws

While the studies tried to correct for other group differences, we can’t say with certainty that sitting X hours less or going from 5 to 75 minutes of exercise per day will make you live X amount of years longer. For that we’d need a large experimental study, which is rare and expensive to do. Still, the results are reasonable given the results of short term intervention studies showing improvements in heart health biomarkers in people after making them exercise, and we feel confident that moving more WILL help you live longer. If you ask us, today’s lifestyle makes it difficult to reach a sitting time of under 4 hours, so the more practical solution is to make sure you reach 65 min of moderate intensity activity per day.

Consider this!

This DOESN’T mean you need to be in the gym for over an hour every day. Rather, consider the following:

  1. 4 gym sessions per week lasting 1 hour. That’s about 35 minutes of daily activity for the week.
  2. Biking/walking 30 minutes to the commute/to work snd home every day. That’s another 30 minutes per day. 3. Going on a weekend walk lasting 1 hour or two 30 minutes evening walks throughout the week. That’s 8 minutes per day for the week. Combining these, you get 73 minutes of physical activity per day, add in minor movements during the day and you can most likely stop worrying about how much you are sitting at the office!

Get moving

We want to add that it probably is a good idea to regularly interrupt longer periods of sitting, even if you’ve been active for over 75 minutes in a day. The study data from the Ekelund meta-analysis doesn’t provide info as to how much of the sitting time is uninterrupted. That means we don’t know if 8 hours sitting time means sitting still for 8 hours or if we are talking about sitting for 1 hour intervals 8 times throughout the day. The latter scenario is more likely.

Also, research shows that regularly breaking up prolonged sitting with for instance a short walk improves health markers (blood suger response). (3,4) We can therefore speculate that moving regularly IS a good idea! Try talking a short walk or leg stretcher every half hour when you know you’ll be sitting for longer periods of time.

Keep in mind that simply standing isn’t good enough (4), you need to MOVE. We suggest using a timer as time flies when you get into a prolonged sitting session. Good luck!

 

THE EVIDENCE:

1. Lee et al. and Lancet Physical Activity Series Working Group. Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy. Lancet, 380 (2012), pp. 219-229

2. Ekelund et al. Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. https://doi-org.ludwig.lub.lu.se/10.1016/S0140-6736(16)30370-1

3. Dunstan et al. Breaking up prolonged sitting reduces postprandial glucose and insulin responses. Diabetes Care. 2012;35(5):976-83.

4. Bailey et al. Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not. J Sci Med Sport. 2015;18(3):294-8.

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