Strength training can aid children’s’ muscular and motor skill development and help establish a life-long habit of injury-free physical activity participation. But, it ought to be one part of a balanced approach to physical activity and the potential for injury means it needs to be closely supervised and only considered when children are capable of responsible behavior.
The capacity to follow directions is one indication of readiness, just as for participation in other youth-oriented activities like soccer and swimming lessons. Readiness should always be considered before introducing children to any activity since a poor experience can result in a sour attitude toward exercise, but it is especially important for strength training given its mandate for strict safety. Executing movement using the correct form is imperative and children should never do 1-repetition maximum lifts, or risk serious injury to soft tissue. In general, up to 3 sets of 10 repetitions, 2-3 times per week with rest days in between body parts is deemed a safe approach. Body weight exercises such as push-ups, pull-ups, and sit-ups also foster muscular development and can be used as a compliment or precursor to strength training.
The increased muscle and soft tissue (tendons, ligaments) development that strength training yields can be an important factor in helping children develop motor skill competency, increasing the likelihood of a sustained habit of regular activity. But it should be one of several types of activity in which they engage. Remember, the deeper their repertoire of activity the stronger their motivation for regular activity across their lifetime. Strength training along with sport practice and other forms of unorganized play such as bike riding, tag/chase games and the use of playground equipment offers the variety of activities optimal toward developing a well-rounded activity portfolio.
For more information, please see the American College of Sports Medicine.