The Canadian Society for Exercise Physiology have published a position stand on this topic and raise the following points in their abstract:
– There is no minimum age for resistance training in children
– Resistance training should include a proper warm-up, cool-down and appropriate exercises
– The intensity should be kept low to moderate and performed 2-3 days per week
– Olympic weightlifting techniques may be incorporated into the training programme
As long as the training and supervision is appropriate, safe, under qualified instruction and uses gradual progression, resistance training can lead to both health and fitness benefits in children and adolescents.