Many teens visit the gym with a dream of packing on so much muscle they will be contenders for a Mr Universe title within a few months.
Very few succeed in gaining even a few pounds of muscle since their approach to the task is as haphazard as most of their activities.
They know what they want, but don't know how to start.
To the teen brain, heavier is best and such weights lifted anyhow will help them reach their target.
Quite the reverse often occurs, since heavy bars in inexperienced hands can cause injury which will delay the gaining process.
It is far better to learn safe and correct lifting techniques using lighter loads.
The untrained body needs time to adjust to the higher demands placed upon it but will reward patience with steady progress.
Before any complex lifts and exercises are attempted the trainee should be taught how to lift barbells and dumbbells from the ground.
A demonstration from a good teacher showing that way the back must be maintained in its natural alignment, with the power for the lift originating from the thigh muscles, will be enough for some.
Others find the squatting movement difficult and round their back when lifting.
I find that encouraging learners to squeeze their shoulder blades behind them helps correct this.
If this fails, a few repetitions on a lat pull down machine can replicate the feeling and posture required.
If the gym has full length mirrors they can be used when learning the proper style.
Even miming the squatting, without using weights will help those not making progress.
Once correct lifting form has been established then individual exercises can be taught.
At first it is better to concentrate on major muscle groups such as the thighs, back, chest and abs.
When these are exercised more growth hormone is produced which encourages muscle gain.
Most teens want bigger biceps to impress their friends but as they represent a quite small proportion of the body's overall muscle bulk, working them only produces small amounts of growth hormone.
However, in order to satisfy the teen's ambitions, the biceps can be given time in the starter schedule.
Depending on the facilities available, there are many exercises for each major muscle group.
Squatting with a barbell, dumbbells or a Smith machine will produce bigger thighs, as will leg press, leg curl, leg extension and hip flexor machines.
Body weight squatting can be made more testing using a one legged squat.
Plyometric exercises will produce more functional muscles and are covered in other articles.
Back muscles can be developed using a lat pull down machine, a pull up bar, bent over rowing with either dumbbells (single arm) or a barbell ( two arms), and using a pec deck machine in reverse, facing the back rest and pulling the pads together behind the back.
The gym favourite, the bench press , can produce large pectoral muscles, but larger growth is encouraged when dumbbells are sometimes substituted for the barbell.
Inclined and declined presses on a bench develop the upper and lower pecs respectively and should be an essential part of the routine.
The cable machines are a good for pecs growth but many learners use too high a weight and bend their arms using bicep strength instead of maintaining good form.
The biceps will grow but there are better movements for that.
The biceps muscles flex the arm and rotate it at the elbow so any movement doing that will encourage growth.
The movement is done with dumbbells, barbells, an EZ bar (an especially shaped bar) and on machines.
A preacher bench, or an inclined bench can be used to isolate the upper arm, so that cheating methods cannot be used to lift the weights by swinging the body.
This brief introduction to teenage bodybuilding should encourage safe muscle growth and develop strength and conditioning for sports, but is not a suggested lifting programme.
My website, www.
teen-gym.
com  Where Serious Teens Grow Seriously, can help plan an individual programme based on the user's needs.