I was on the train home from London yesterday afternoon after watching England do something good/surprising in the Football, and this question came up. He had seen my new client Rowan performing Snatches (and performing them very well) and said "I thought weights were bad for younger people. I thought you had to wait until they were older". I have also heard this many times over my years of being a coach.
So, lets get into this
Weightlifting has been proven to be an effective training method for improving an athletes Strength, Power, Mobility, Rate Coding and Rate of Force Development. Weightlifting has proven time and time again to be a useful tool for enhancing the performance of athletes from many different sports including Running, Tennis, Basketball, Swimming and more (lots more).
There are a lot of misconceptions when it comes to youth training. I hear far too often people stating that "lifting weights will stunt growth" or "it's bad for their joints". This is totally untrue, a study by Lloyd, Rhodri S. PhD et all stated "There is no evidence indicating that weightlifting, and more generally resistance training, is especially injurious to the epiphyses or has a direct correlation with reductions in eventual growth height in young athletes.".
Injury rates in Weightlifting has also been shown to be very low. Pierce et al. found that "during a year long period of weightlifting competitions and training sessions, injuries incurred directly from weightlifting resulted in no loss of training days in a sample of 70 boys and girls (aged 7–16 years), who regularly completed maximal and near-maximal lifts in competition.". Weightlifting in fact has one of the lowest injury rates of any sport. Yes, you are lifting a lot of weight over head, however, like I told Rowan "when it goes wrong, the weight will only fall to the floor - 9.9 times out of 10 it will just fall in front of you". The big injuries you see are when elite athletes are fighting for a lift which they ought to drop, but don't as they are fighting for a medal.
Many youths will be already performing high force output activities such as high velocity running, jumping & landing, climbing & and the list goes on. The physiological adaptations obtained from Weightlifting (and lifting weights) can better prepare the youth for these activities.
Of course, there is many considerations to keep in mind when planning an exercise programme for a youth. Considerations to biological age & chronological age, exercise frequency, exercise volume, exercise selection and training age must be made.
In conclusion, the addition of properly implemented Weightlifting movements and exercise will help greatly with both physiological, and psychological development in youths.
If you do have any questions, please get in touch!