TV and Hypertension in Kids
While many parents worry that the violence on TV will give their kids a thirst for blood, few worry about the effect of TV on their kids' blood pressure. After all, high blood pressure is an adult disease -- or at least has been. But increasingly, those still in elementary school have proven to be at risk, and now a new study shows that watching too much television may be a risk factor.
It doesn't take a Nostradamus to predict that kids who spend lots of time plunked in front of a television might be less healthy than those regularly outside slamming softballs. You would think the same holds true for those kids who remain sedentary playing with computers for hours on end. But in fact, the study just published in the Archives of Pediatrics and Adolescent Medicine found that while watching television does indeed raise blood pressure, computer time doesn't.
The subjects included 111 children aged three to eight. All the kids wore devices that measured their overall activity levels. In addition, their parents reported how much time the youngsters spent watching TV, playing video games, painting, sitting or doing other low-level activities. The average amount of sedentary time was five hours daily, with 1.5 hours spent in front of a screen. TV time was defined as time spent watching TV, videotapes or DVDs. Screen time was defined as the total amount of time using a TV, video, computer or video game. Although boys spent more time at the computer, their overall inactive time equaled that of the girls.
As it turned out, "Sedentary activity per se was not significantly related to systolic blood pressure [the top number in a reading] or diastolic [bottom number] blood pressure, after controlling for age, sex, height and percentage of body fat," said study director David Martinez-Gomez, of Iowa State University and the Spanish National Research Council in Madrid. "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." Overall, those children who spent the least amount of time in front of a screen had far lower blood pressure than those who spent the most time.
Again, the idea of checking those barely out of diapers for high blood pressure may seem bizarre, but in fact, the American Heart Association suggests regularly monitoring blood pressure in children over the age of three. While only one percent of young children had hypertension just 20 years ago, by 2002 that percentage had increased fivefold, with an additional several percent pre-hypertensive. And among inner city and minority kids, up to 25 percent now have the condition. And over the last ten years, those numbers can only have continued to increase.
As with hypertensive adults, weight usually is a factor, but in this study, the kids who watched the most TV had higher blood pressure even when weight wasn't an issue. "These results show that sedentary behavior, and more specifically television-viewing, is related to blood pressure independent of body fat or obesity level," said Dr. Joey Eisenmann of Michigan State University, another study author.
What then, is it about watching television that raises blood pressure more than checking email, even in the absence of obesity, assuming that the results of this study are accurate? The study authors point out that watching television requires absolutely no movement whatsoever, whereas working at the computer burns at least a few calories as you pound the keyboard or move the mouse. Plus, they note, many kids snack along with their favorite shows, stuffing junk foods into the mouth as they watch commercials that plug cookies and chips. Although the study didn't measure how much kids eat while watching Sesame Street versus updating their My Space accounts, the researchers assume TV leads to more unconscious junk-food gorging than computing does. After all, studies show that the average kid watches 10,000 food commercials on television every year -- and the foods advertised tend to be blood-pressure elevating salty and sugary treats.
The experts also say that watching TV at night can stimulate kids and disturb sleep, which raises blood pressure -- but of course, so can cruising the internet, so that argument doesn't hold up. But unlike working the internet, sitting in front of the TV apparently leads kids into an almost coma-like state, where calorie burning falls to zilch. Says Dr. David Ludwig of Children's Hospital in Boston, "Some studies suggest that the metabolic rate can fall even below that of sleeping. They suggest that children are getting into some deep hypnotic state at times."
And it is here, I believe, that the researchers are finally "touching" on the key issue: mental activity burns calories. The higher the level of mental interaction, the more learning involved, the higher the consumption of calories. For example, calorie consumption while playing chess is over fifty percent higher than when watching TV -- and that's in adults. When it comes to children, energy consumption in the brain is more than two times higher for toddlers than for adults because of all the learning and brain structuring taking place in the formative years. And although this energy spike begins to drop off after age four, the brain's energy consumption levels do not level out until after age 10. Even more important, during periods of peak performance, energy consumption in the brain goes up another 50% for both adults and children.
The bottom line here is that there is a vast difference between energy expenditure and calorie burn while working interactively with a computer (or playing a mentally challenging game or puzzle solving) as opposed to passively watching TV.
And while high blood pressure spikes in childhood don't necessarily mean the child will develop hypertension, evidence indicates that youthful sloth leads to adult health issues. But the authors note that, "The clustering of cardiovascular disease risk factors in overweight youth suggests that risks may be immediate and not just indicative of potential future problems." To minimize that risk, they suggest that kids get a daily hour of exercise and watch TV no more than a few hours a day. (Very generous of them, I must say.) Add to that recipe slashing junk food consumption, making sure that active time (not just exercise time) far outweighs overall sloth time, and setting a good example. After all, if parents collapse by the TV for hours on end every evening, what lesson does the child learn?