Weight Training for Teenagers, the Sooner you Start, the Better By Ricardo d Argence | December 2, 2008 by Ricardo d Argence More and more teenagers are taking up bodybuilding. Getting in shape and building muscle is not a bad idea if it is done correctly. Many key areas of the body are still developing during the teen years, although their bodies may appear to have reached adult height. Teenagers in search of an excellent body building routine need to include nutrition, weights and rest.