Sedentary behaviour refers to activities that need very little physical movement and don’t use much energy, such as sitting or lying down for long periods of time. It is often called “too much sitting.” Sedentary behaviour is different from not getting enough exercise.
Researchers recognize sedentary behaviour as a health risk. Sedentary behaviour contributes to weight gain and becoming overweight or obese. It is associated with health problems including:
Sedentary behaviour may be measured in different ways.
The SITT formula may be used to describe the frequency, interruptions, time and type of sedentary activity.
Canadian adults are sedentary for most of their waking hours. For men, 68% of their waking hours are sedentary. Women spend 69% of their waking hours in sedentary activities.
Many Canadians spend a lot of their leisure time in sedentary activities. People are spending more and more time watching TV, using a computer, watching videos and playing online or video games. These screen-based forms of entertainment are examples of activities that usually involve a lot of sitting. Prolonged sitting also occurs with increased time spent in automobiles and sitting in the workplace (occupational sitting).
A growing body of evidence supports a link between sedentary behaviour and an increased risk for cancer. The health risk from sedentary behaviour is not influenced by the amount of physical activity a person does, so it is an independent risk factor. Sitting for long periods of time can increase cancer risk, even in people who exercise regularly. Even if you exercise for 30 minutes or more a day, but spend the rest of the day in sedentary activities, you can still be at an increased risk for cancer. It is likely that the longer a person sits, the higher the risk. Research suggests that sitting for long periods of time uniquely affects certain body functions. Sedentary behaviour can cause the following cell and metabolic changes, which may contribute to cancer developing:
Higher amounts of sedentary behaviour are associated with an increased risk of colorectal cancer.
There is some research that suggests work that is sedentary (occupational sitting) is linked to uterine (endometrial) cancer, but the evidence is limited and more research is needed to confirm this.
The evidence around the effect of sedentary behaviour on cancer risk is new and still emerging. Further study is needed to clarify the role of sedentary behaviour for different types of cancers and identify effective ways to reduce sitting time.
Research shows that Canadian children and youth spend the majority of their leisure time in sedentary activities.
Most of the evidence on the effect of sedentary behaviour on cancer risk comes from studies done on adults. Studies on the health risks of sedentary behaviour in children and youth have mainly looked at weight or body mass index (BMI), fitness, metabolic syndrome, school performance and other psychosocial effects. Researchers are studying whether sedentary behaviour during childhood and adolescence is a predictor of being overweight or obese during adulthood.
Studies suggest that moving more to decrease the amount of time you spend sitting may help reduce your risk of cancer and improve your overall health. Tips to help reduce sitting time include:
In general, everyone should follow the guidelines for physical activity for their age group and limit time spent in sedentary behaviours. Being active has many health benefits, including reducing the risk of certain cancers.
In 2011, Canada released sedentary behaviour guidelines for early years, children and youth. For more information on the Canadian Sedentary Behaviour Guidelines, go to the Canadian Society for Exercise Physiology.