According to a study of 111 children, TV viewing and screen time appear to be associated with elevated blood pressure in children independent of body composition.
The recent trend in obesity is a major public health concern and its effect on blood pressure is of particular concern. “The clustering of cardiovascular disease risk factors in overweight youth suggests that risks may be immediate and not just indicative of potential future problems,” the authors write. Although elevated blood pressure is associated with genetic factors, healthy physical, dietary and sleep habits seem to be relevant contributors to blood pressure levels in children. However, there have not been any clear links between sedentary behavior and elevated blood pressure in children younger than age 9.
The researchers examined associations between sedentary behavior and elevated blood pressure in 111 young children (57 boys and 54 girls ages 3 to 8). Sedentary behavior was determined by an accelerometer generally worn over the right hip and by parental reports stating the average time the children spent watching TV, playing video games, painting, sitting or taking part in other activities with low levels of physical activity each day for seven days. Time watching TV was defined as time spent watching TV, videotapes or DVDs. Computer use was defined as the time spent using a home computer or video game. Researchers defined screen time as the total amount of time each child spent using a TV, video, computer or video game. The children’s height, weight, fat mass and systolic blood pressure and diastolic blood pressure were also measured.
Blood pressure is measured in millimeters of mercury (mm Hg), and expressed with two numbers, for example, 120/80 mm Hg. The first number (systolic pressure) is the pressure when the heart beats while pumping blood. The second number (diastolic pressure) is the pressure in large arteries when the heart is at rest between beats.
The children’s average sedentary time and screen time per day were five hours and 1.5 hours, respectively. Boys spent more time using computers than girls, but there were no significant differences in time spent on other sedentary behaviors. “Sedentary activity was not significantly related to systolic blood pressure or diastolic blood pressure after controlling for age, sex, height and percentage of body fat. However, TV viewing and screen time, but not computer use, were positively associated with both systolic blood pressure and diastolic blood pressure after adjusting for potential confounders,” the authors write. “Participants in the lowest tertile [one-third] of TV and screen time had significantly lower levels of systolic and diastolic blood pressure than participants in the upper tertile.”
“In conclusion, the results of this study showed that TV viewing and screen time were associated with elevated blood pressure independent of body composition in children,” the authors write. “Given that total objective sedentary time was not associated with elevated blood pressure, it appears that other factors, which occur during excessive screen time, should also be considered in the context of sedentary behavior and elevated blood pressure development in children.”
References:
1. David Martinez-Gomez, et al. Associations Between Sedentary Behavior and Blood Pressure in Young Children. Arch Pediatr Adolesc Med. 2009;163[8]:724-730.
