The question weather children should engage into exercising is a Rhetorical one with a capital bold letter “R”. This doesn’t mean the t children should attend in the gym and lift weights – No. they should do quite the opposite. Sitting at home, watching TV and playing the computer affects negatively to both adults and children. Nowadays, elderly people seem to be more aware of the passive attitude from non-physical activity then children.
What is the point? – Its simple, when the human body is in the state of growing and developing physically it is in the stat of developing an effective immune system also. Form the age of 10 to 20, the body goes through major changes, especially in puberty. Although the normal changes occure in teenagers (boys grow beards and girls start their “period”) they also are in the state of growing taller and developing the muscles. To direct a child, in his teen years, to visit the gym to improve his physical ability is a bad idea. When the body is in puberty, it has to develop naturally as all homo-sapiens do. Lifting weights won’t speed things up or improve strength. It will do the opposite – the muscles will be sensible to overtraining, so will the bones.
Instead of pointing your child to the nearest gym with barbells and dumbbells, point him in the direction to a basketball court, to a soccer practice, to the nearest pool, let them drive a bycicle and etc. Allowing the body to expand its capabilities in the form of running, jumping, sweating and all the natural movements will catapult the metabolism, physical stamina, muscle growth, bone strength, height … you name it. It is far better to play basketball on a sunny weather with friends, then to enter a gum and just lift heavy weights. There is plenty of time for the gym after the 20th year of age (if your child chooses).
Whatever sport your child chooses, or you choose for him, it is great: just make sure it isn’t weight lifting. To pile the body with weight lifting in puberty is a pure torture. Let it grow and develop naturally he way it’s supposed to develop and then see whether you need barbells.