Should kids participate in strenuous exercise?

A 14 year old is a freshman in high school typically. Weight training is so beneficial for their overall fitness, but also for building up their athletic ability through enhanced central nervous system stimulation and gains in muscular/bone development. I do think though that middle school aged students should begin with a strong body weight plan first before moving on to the weight room. Thinking about biological age vs. chronological age! Some kids are more ready than others.