Source 1: (https://www.ncbi.nlm.nih.gov/m/pubmed/23914510/)
This article is explaining that training at such a young age is not bad as long as you train safely. Strength training requires lots of supervision and appropriate overload with young children for their safety. Recovery time for kids is a big thing to be able to not stunt growth. All they explained is that taking lifting for young children should be taken slow and not rushing to anything to fast make sure to get proper technique down.
Source 2: (http://www.acsm.org/public-information/articles/2016/10/07/youth-strength-training-facts-and-fallacies)
In this article they explain that children should do 60 minutes a day to moderate activity.This article explains the myths that come to strength training for kids and they are, strength training will stunt growth, children will experience bone growth plate damage, strength training is unsafe for young children. They believe that this isn’t consistent and is very unsafe for children. They also explain that this requires adult supervision because of the dangers that can take place when strength training.
This article explains a lot of good in strength training for kids they say that it helps kids out a lot when being active in sports help prevent injuries to weaker muscles. It explains that you hear more about kids getting hurt in the gym when it’s a accident with a object rather than something dramatic happening from lifting.they explain when you hear it will stunt growth in children their concerns would be injured disc or growth plates.
Many cases that happen this article explains the main risk and concerns are that there is lack of supervision that are the main reason for injuries to occur. Then other times children get hurt when doing heavy lift with not proper form and just messing around trying to lift heavy.
When children do heavy lifts or max weight training it can create possibly pain in the musculoskeletal injuries such as a ruptured disc. They say that it’s not a bad thing to workout at a younger age but to just be cautious and to take it slow and steady.