Shortly after a baby turns one years old, he or she begins to crawl, toddle along and eventually walk.

London - Every extra hour of television that a toddler watches weekly takes a toll on their waist size and athletic ability by the time they turn 10, scientists claim.

Waistlines of 10-year-olds who had watched 18 hours a week at the age of four were 7.6mm bigger than those of children who had watched the average amount of 14.8 hours, the study found.

The distance children could jump was also reduced by a third of a centimetre for each extra hour of TV they had watched per week at the age of two.

The two-year-olds monitored in the study watched an average of 8.8 hours per week, rising to 14.8 hours for the four-year-olds.

About 15 percent of the 1 314 children analysed were already watching more than 18 hours of TV a week, the University of Montreal researchers found.

It is hoped that the study, published in the International Journal of Behavioural Nutrition and Physical Activity, will encourage authorities to target the factors behind childhood obesity.

Researcher Dr Linda Pagani said: “The bottom line is that watching too much television is not good.

“Across the [Western] world, there have been dramatic increases in unhealthy weight for children and adults in recent decades.

“Our standard of living has also changed in favour of more easily prepared, calorie-dense foods and sedentary practices. Watching more television not only displaces other forms of educational and active leisurely pursuits but also places them at risk of learning inaccurate information about proper eating.

“These findings support clinical suspicions that more screen time contributes to the rise in excess weight… thus providing essential clues for effective approaches to its eradication.”

Her fellow researcher, Dr Caroline Fitzpatrick, said: “The pursuit of sports by children depends in part on their perceived athletic competence.

“Behavioural dispositions can become entrenched during childhood as it is a critical period for the development of habits and preferred activities.

“Accordingly, the ability to perform well during childhood may promote participation in sporting activities in adulthood.’

Meanwhile, another study has found that couch potato kids are more clumsy than those who are active.

It found that those who sat around for most of the day were up to nine times less likely to have normal levels of co-ordination.

Importantly, brief bursts of strenuous exercise did not make up for the damage apparently done by a sedentary lifestyle.

The study tracked the movements of more than 200 children aged nine and 10 using a gadget to measure activity levels over five days.

The children were tested to measure their balance, speed and co-ordination, including walking backwards on a beam. On average, the youngsters spent three-quarters of their time sedentary – defined as sitting or lying down – with the girls less active than the boys.

However, the impact on co-ordination was greatest for the boys, with male couch potatoes five to nine times less likely to have normal co-ordination, the Journal of Human Biology reports.

The findings stood even when height, weight and other exercise were taken into account.

Researcher Dr Luis Lopes, of Minho University in Portugal, said good co-ordination was linked to a healthy weight and heart: “Childhood is a critical time for the development of motor co-ordination skills which are essential for health and well-being.” – Daily Mail