A new study shows that adults under age 60 whose days are filled with sedentary leisure time and little physical activity have a much higher risk of stroke than more physically active people.

It's confirmed: too much sedentary leisure increases the risk of stroke

With the development of an abundant digital offer and new technologies, the current context has never been so favourable to the increase of sedentary time and especially of "screen time". A new study published by the American Heart Association in the journal "Stroke" illustrates one of the dangers of this very bad habit on cardiovascular health, namely the increased risk of stroke. The researchers started from the observation that while the association between physical activity and a lower risk of stroke is well established, the relationship between sedentary leisure time (screen use, reading) and stroke is less well studied.

"Sedentary time is the duration of waking activities performed while sitting or lying down. Sedentary leisure time is specific to sedentary activities performed outside of work," explains lead study author Prof. Raed Joundi of the University of Calgary. "It is important to understand whether periods of sedentary activity can lead to stroke in young people because stroke can lead to premature death or significantly impair function and quality of life." In this study, researchers examined health and lifestyle information from 143,000 adults without a history of stroke, heart disease, or cancer.

Fourfold increase in risk after eight hours of sedentary time per day

The participants were followed for an average of 9.4 years and each case of stroke among this panel was identified through a linkage with their hospital records. At the same time, the scientific team reviewed their time spent each day in sedentary leisure activities. Responses yielded several categories: less than four hours of sedentary leisure activities per day, four to less than six hours per day, six to less than eight hours per day, and eight or more hours per day. The same process was implemented regarding their exercise practice, knowing that being the least physically active was equivalent to walking 10 minutes or less per day.

The researchers found that the average daily sedentary leisure time for all participants was 4.08 hours, and that adults aged 60 years and younger who had low physical activity and reported 8 or more hours of sedentary leisure time per day had a 4.2-fold higher risk of stroke than those who spent less than 4 hours per day. In addition, the most inactive group of participants (those reporting 8 or more hours of sedentary time and very low physical activity) had a 7-fold higher risk of stroke compared with participants reporting less than 4 hours of sedentary time per day and higher levels of physical activity.

The double beneficial effect of physical activity

The risk of stroke was primarily for ischemic stroke, the most common type of stroke, which occurs when a vessel supplying blood to the brain is blocked by a clot. "Adults aged 60 and younger need to be aware that very high sedentary time with little time spent on physical activity can have adverse health effects, including an increased risk of stroke," adds Prof. Raed Joundi, who emphasizes the importance of physical activity. "It reduces the actual time spent without moving and also seems to decrease the negative impact of excessive sedentary time."

In their conclusions the researchers believe that physician recommendations and public health policies to reduce the risk of cardiovascular events should emphasize increasing daily physical activity while insisting on reducing sedentary time. This is especially true since their study specifies that sedentary time in relation to professional activity was not taken into account, which means that the time spent sitting is underestimated among people who hold office jobs. It should be noted that according to the World Health Organization, up to 5 million deaths per year could be avoided if the world's population was more active.