Our second expert is Kate Sansum, a former student at the University of Bath, who is now studying the impact of prolonged periods of sitting down on health at the University of Exeter. So let’s get stuck in and learn about why breaking up sitting time is a good thing!!
Key question: Why is breaking up prolonged sitting time so important for our health?
As you probably know, many people are spending an increased amount of time sitting down, both in the workplace and during our leisure time (e.g. watching TV) compared to previous generations. The COVID-19 pandemic and lockdown will have increased our sitting time. To make this even worse, any small breaks in our sitting time are often shorter with the kettle only a few steps away rather than walking to our favourite coffee shops.
Sedentary time and physical activity were once thought of as two sides of the same coin, but they actually have independent effects on our health, and you can be both highly sedentary and physically active. For example, someone might go to the gym for 30 minutes, five times a week (so meeting the government recommendations for moderate-high intensity exercise) but spend the rest of the day sitting down...
Why is prolonged sitting bad for our health?
Increased time spent sitting is linked with an increased risk of diseases such as cardiovascular disease and type 2 diabetes, but being physically active can help to reduce this risk. The time scale to see these effects is probably shorter than you might think. A study in adults showed negative effects on the function of small blood vessels (capillaries) after sitting still for just 10 minutes!! Sitting for long periods of time also negatively affects how well we are able to process the food and drinks we consume, with increases in blood sugar and fat levels compared to when the sitting periods are interrupted with small doses of physical activity.
So what can I do?
1) Move more when you can! The best strategies for breaking up sitting time for health are still being refined, but positive effects on blood vessel function have been shown with walking breaks, intense fidgeting and even sitting with straight legs rather than bending at the knee. Interrupting sitting with walking breaks is also good for blood sugar control. High intensity activity breaks have also been shown to reduce the increase in blood fat levels after a meal. Example strategies could also include walking to a colleague instead of emailing (once the pandemic is over of course), climbing the stairs instead of using a lift and going for short walks when you can (e.g. get moving during your lunch break!!).
2) Get a standing desk? Well, the use of standing desks in offices as an alternative to sitting, might not be as beneficial as you might think. Researchers have found it only increases the number of calories burned by 9 calories per hour compared to sitting. However, standing helps prevents the decline in blood vessel function seen when sitting for three hours, so the effectiveness of standing desks may depend on what health benefits you are looking for.
What about young people?
Evidence shows that young girls experience a decline in blood vessel function from prolonged sitting, but this can be prevented with hourly moderate intensity activity. We know children and adolescents’ also experience negative changes in metabolism from prolonged sitting. As children and adolescents increasingly spend more time indoors (e.g. playing video games) this is an important area to target, especially as habits we create in childhood and adolescence can stick with us into adulthood. My own research now studies the effect of interrupting sitting with hourly high intensity exercise on blood vessel function in adolescents before and after a meal. These findings will help us to understand the best guidelines for sedentary behavior (like we have for exercise and physical activity).
Take home message: Sedentary time and physical activity are similar, but not the same. Breaking up long periods of time you spend sitting by regularly doing a few minutes of activity is important for health. We are working on the best activity strategies, but more frequent & short breaks (e.g. every 30 minutes) have been suggested to be effective.
Thanks for another great addition Kate! For more evidence-based blog posts about exercise, diet and healthy habits sign up by clicking here.
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