Lots of time spent in front of a TV early in life may have lasting consequences, indicates a study that connected the viewing habits of Canadian toddlers with waist circumference and muscular fitness later in childhood.
Using data collected periodically for 1,314 kids participating in the Québec Longitudinal Study of Child Development, researchers found increases in TV viewing starting when kids were 29 months old were linked to reduced jumping ability in second grade and bigger waist circumferences in fourth grade.
The implications may be lifelong, write the researchers: "The preschool years represents a period of remarkable sensitivity to environments and experiences, and thus account for the origins of many lifestyle behaviors and preferences."
Past research has found that too much TV-watching at age 2 is associated with less engagement in classroom activities, less weekend exercise and a greater chance of being picked on by classmates in fourth grade.
In the new study, the researchers used the standing long jump as a measure of physical fitness, because it requires the explosive leg strength necessary for many sports.
Waist circumference, meanwhile, is a measure of abdominal fat and can be linked to poor cardiovascular health and other problems. Plus, extra weight carried when a child is heading into adolescence likely represents more health risks than weight gained during other periods of development, they write.
The American Academy of Pediatrics recommends that toddlers watch no more than two hours of television per day; however, many exceed that during this critical period for the development of habits and preferences, according to the authors.
As part of the longitudinal study on child development, parents of participating children were asked "How much time per day does your child spend watching TV?" when the kids were 29 and 53 months old, just shy of 4.5 years.
Follow-up interviews years later found that for each hour per week the kids spent in front of the TV when they were 29 months old, the distance they were able to jump decreased by 0.14 inches (0.361 centimeters) when they were in second grade.
From 29 months to 53 months old, every hour of TV-watching a week was linked to an additional 0.11-inch (0.285 cm) decrease in the second-grade jump, as well as a 0.2-inch (0.047 cm) increase in waistline when they were in fourth grade. [8 Reasons Our Waistlines Are Expanding]
"TV is a modifiable lifestyle factor, and people need to be aware that toddler viewing habits may contribute to subsequent physical health,"the team's lead researcher, Caroline Fitzpatrick of New York University, said in a statement. She conducted the research while at the Université de Montréal and Saint-Justine's Hospital Research Centre.
Though scientists realize it can be tricky to limit television, there are TV-limiting tips that can make it easier, such as taking TVs out of kids' bedrooms and using on-demand television to curtail viewing time.
The research is detailed today (June 15) in the open access journal International Journal of Behavioral Nutrition and Physical Activity.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.