Summary:

It's not easy to determine how early to start children in organized sports. Children of the same age vary considerably in their physical and psychological maturation, and there is no practical method of measuring maturity. Assuming the child has shown interest, five or six is the generally accepted earliest starting age for organized team sports. At the early ages participation should be limited to sports that involve a lot of physical activity and encourage the development of major motor muscles.

Opinion: I think that children should start playing sports as soon as possible. The children will be able to find a hobby fast and be healthy since young. I think there should be more sports  activitiesfor young kids.