A study indicates American youngsters walk less than those in other countries. Researchers say this helps explain why a greater proportion of American kids are overweight. And other experts say kids would walk more if parents didn't have to shuttle them around so much. The researchers gave pedometers to 1,954 children, ages 6-12, in the United States, Sweden and Australia. The number of steps shown on the pedometer was compared with the child's body-mass index — an estimate of body fat based on height and weight. "In general, the Swedish children were significantly more active than the Australian and American children, and the American children were significantly heavier than the Australian and Swedish children," the study said. Associated Press