Too much TV may do more than interfere with a child's grades -- it also might affect his or her athletic development, a potential problem for those parents who dream of raising the next Michael Phelps or Serena Williams.
A study published in the International Journal of Behavioral Nutrition and Physical Activity is believed to be the first to document the relationship between how much TV time a child logs and later explosive leg strength -- a key indicator of athletic prowess.
The other key finding, while significant, is perhaps less surprising: Kids who watch more TV early in life were likely to have wider waist measurements down the road, an indication that the lack of activity was putting young children on a path toward obesity.
Lead researcher Caroline Fitzpatrick, a post-doctoral researcher at New York University, joined researchers at the University of Montreal in studying 1,314 children in Quebec. Parents participating in the study were asked how much time their children spent watching television at ages 29 months and 53 months.
As second-graders, the children were tested using a standing long jump as an indicator of explosive leg strength, speed and power. As fourth-graders, they were assessed with a simple tape measure to document their waistlines.
The study is the latest to suggest that parents who want to raise healthy kids need to slash their screen time.
"Children who watch more television are more likely to develop poor dietary habits, sleep disturbances, and become obese," the study said. "Because it represents a sedentary activity which takes time away from other more physically demanding pursuits, the amount of time children spend watching television in early childhood raises concerns over potential consequences for later physical fitness during the school years."
But how much TV is too much? The study doesn't say, specifically. But it does say that each hour of TV per week at 29 months corresponds to a diminished performance in the standing long jump. Further, the increase of an hour per week between 29 months and 53 months was linked to an even worse performance in the standing long jump -- and measurable increase in waist size.
The study concluded: "Early interventions aimed at modifying toddler viewing habits may contribute to subsequent physical health and athletic performance."