Frequent breaks from sedentary behavior makes kids healthier
Canadian kids spend more than half their waking hours engaged in sedentary behaviour - watching television, playing video games or just sitting around. Studies involving adult populations suggest that breaks in sedentary time are associated with reduced global health risks. Today these findings have been replicated in a study involving children between the ages of 8 and 11 as published in PLOS ONE.
“We already know that sitting too much is bad for kids,” says Travis Saunders, who earned his PhD at the University of Ottawa and is a researcher at the Children’s Hospital of Eastern Ontario (CHEO) Research Institute. “But now, for the first time, we have evidence that simply getting up more frequently is associated with better health in this age group.”
Researchers looked at risk factors for type 2 diabetes and cardiovascular disease in children with a family history of obesity. They analyzed data taken from an existing QUALITY cohort study that included over 500 children living in Quebec. Using an accelerometer to gather data, the researchers studied all breaks in sedentary behaviour for these kids during a one week period.
Global health risk indicators were measured, including waist circumference, body mass index, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol and C-reactive proteins. Time spent at the computer and playing video games as well as television viewing during the 7-day period was self-reported.
“Increased screen time poses a persistent health risk for kids as a rule,” continued Saunders. “But what’s also interesting in this study is that video-gaming was associated with higher risk scores for boys whereas television viewing was linked to higher risk scores for girls.”
This study suggests that frequent interruptions in children’s sedentary time - or the number of times children got up, rather than the duration of the break - can have a positive impact on their health.
Sedentary or ‘still’ time spent watching TV, DVDs or playing on the computer is linked to children being overweight and obese. This is partly because the time children spend on small screen activities takes away from the time they could spend being physically active.
Children who watch TV for more than two hours each day are more likely to have an unhealthy diet, less likely to eat fruit and less likely to participate in physical activity.
However, 89% of children aged between four and five years spend more than two hours watching TV, videos or DVDs every day.
In addition, it’s more likely that kids will snack on foods that are high in sugar, salt and fat when they watch TV and many ads about food and drinks are directed towards children.
These ads are often for fatty, high sugar ‘extra foods’ and use branding that is highly appealing to children. Kids recall, enjoy and engage with this branding and it can strongly influence their preferences, purchases and consumption of particular foods and drinks.
Studies have shown that children under eight years have difficulty distinguishing between TV programs and TV ads.
Healthy lifestyle initiatives that target sedentary behaviour in children, particularly small screen recreation, have the potential to make a positive impact on health issues associated with being overweight or obese.
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Sedentary behaviour and cancer
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:
- increased weight gain that leads to being overweight or obese
|__ Being overweight or obese has been linked to several cancers.
changes in sex hormone levels
Increased androgen levels in men and increased estrogen levels in women are linked to hormone-related cancers, such as prostate cancer and breast cancer.
|__ Sex hormone binding globulin (SHBG) binds to sex hormones and inactivates them. Decreased levels of SHBG may affect cancer risk. Physical activity increases SHBG levels, whereas inactivity decreases SHBG levels.
- higher blood sugar (glucose) levels, increased insulin levels and insulin resistance
|__ Cancer cells use glucose to grow and multiply, so increased blood sugar levels may promote cancer cell growth.
|__ High insulin levels may increase insulin-like growth factor, which is involved in cell differentiation, growth and programmed cell death (apoptosis).
|__ Insulin resistance may also promote the development of cancer in complex ways.
Reducing your risk
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:
- Take frequent, short breaks from sitting. Breaks as short as standing or moving for 2–3 minutes can be beneficial. Even simple muscle movement has a beneficial effect on cell processes.
- Walk around while you are talking on the phone.
- Stand, rather than sit, on the sidelines while watching recreational games.
- Take regular desk breaks to reduce sitting time while you are at work.
|__ Walk to a central office waste basket or recycle container.
- Take standing breaks during meetings.
|__ Use a standing desk, if one is available, or sit on a therapy ball instead of an office chair.
- Limit the amount of recreational time you spend watching TV or videos and playing on a computer.
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 all age groups.
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