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Today’s post comes from Drs Annemarie Koster and Julianne van der Berg. For more information on their work, please see the bottom of this post.
Doing desk work, watching TV, commute. In daily life sitting is the most common behaviour. Unfortunately, sitting has been indicated as the new smoking, meaning that the current sedentary lifestyle has a highly negative impact on health. For example, we previously showed that more time spend in a sedentary position was associated with a higher risk of having metabolic syndrome and type 2 diabetes. But being sedentary has also been related to mortality, cardiovascular diseases and cancer.
Clearly, the amount of sedentary time should be reduced. Reducing sedentary time inevitable results in more non-sedentary time, such as standing or walking. However, the health benefits of standing may differ from those of walking. So, the effects of reducing sedentary time depend on the activity with which it is replaced.
To get more insight into these effects, an isotemporal substitution model can be used. This statistical approach gives information about the effect of a theoretical replacement of one behaviour (e.g. sedentary behaviour) with another (e.g. standing). In our current study we used such a model to examine the replacement effects on the metabolic syndrome and type 2 diabetes.
In our study, data were taken from The Maastricht Study, which is an observational, prospective, population-based cohort study in the Netherlands. We included 2213 participants (mean age 60 years, 51% men) who wore an accelerometer (ActivPAL) 24 hours per day for 7 consecutive days. We calculated the daily amount of sedentary time, standing, and stepping (e.g. walking) time. To determine diabetes status, participants underwent an oral glucose tolerance test. Metabolic syndrome was defined as having at least 3 of the following risk factors: a large waist circumference, high fasting glucose levels, low HDL cholesterol levels, high levels of triglycerides, and hypertension.
During the time the participants were awake, on average 9.4 hours (60%) were spent in a sedentary position. The remaining waking hours were spent standing (4.3 hours) and stepping (2.0 hours). When sedentary time was reduced by 30 minutes and replaced with 30 minutes of stepping, the risk of having the metabolic syndrome lowered with an impressive 28%. The risk of having type 2 diabetes was lowered with an equal impressive 21%. Remarkably, replacing 30 minutes of sedentary time with 30 minutes of standing also significantly reduced the risk of metabolic syndrome with 7% and for diabetes with 6%.
So, our results show that just 30 minutes less sedentary time a day can considerably lower the risk of metabolic disease. Even replacing 30 minutes of sedentary time with simply standing could have beneficial health effects.
It indicates that small lifestyle changes can make a big difference for people’s health.
We believe that a public health message focussing on sitting less (rather than exercise more) is a more feasible approach for people to change their sedentary lifestyle in the long run. Long-term intervention studies are now needed to prove that this approach is indeed feasible and importantly also results in long-term health benefits.
Annemarie Koster, PhD is associate professor at Maastricht University and is part of the management team of the Maastricht Study. Her physical activity research line focusses on objectively measured physical activity and sedentary time. She has a specific interest in sedentary behaviour as a risk factor for type 2 diabetes and other health outcomes and is leading several projects on this topic. LinkedIn | ReserachGate
Julianne van der Berg, PhD has a research interest in the health effects of sedentary behaviour and physical activity as measured by accelerometry. Her PhD research project, conducted at Maastricht University, focused on sedentary behaviour and cardio-metabolic health. She is currently working as an epidemiologist at the Radboud university medical centre in Nijmegen, the Netherlands. LinkedIn | ReserachGate