Health experts believe that that poor nutrition and sedentary lifestyle are the most important factors in the obesity problem. However, new research shows that decreasing time spent being sedentary or the so-called “screen time” (because this is the time spent in from of the TV or computer screen) is only half of the story.
British researchers report that physical activity is the key to decreasing body fat in children. And not just normal daily “moderate” activity. Vigorous exercise is necessary.
Researchers at the MRC Epidemiology Unit in Cambridge, UK looked at 1,862 children aged 9 to 10 years old, of whom 23 percent were overweight or obese. The study participants were asked to wear a wrist-watch like sensor that measures and records the amount and intensity of physical activity engaged in. Body mass index (BMI), body fat, and waist size were measured. The number of hours spent by the children in the front of the TV or the computer was also recorded. The results show that
- The majority of children engage in physical activity of moderate amount (at least an hour) and intensity.
- More than half of the participants have screen time less than hours each day.
- Children who spent more time being sedentary tended to have excess weight and body fat
- Children engaged in vigorous activity have smaller waist circumference and less fat mass.
- Boys got an average of 30-minute vigorous exercise each days; girls only 22 minutes.
The study showed that vigorous physical activity is a very strong determining factor in keeping down body fat mass and waistline. Moderate activity alone cannot achieve this.
For instance, every 6.5 minutes a child spent doing vigorous activity like playing ball, bicycling, or running around outside was associated with a 1.32-centimeter reduction in waist size, the researchers found. But 13.6 minutes of moderate physical activity only reduced waist size by half a centimeter.
The results indicate that reducing sedentary time alone is not enough to prevent obesity. Additional vigorous physical exercise is needed to keep down weight. The authors concluded: