Strength training using your body weight or lighter free weights for resistance is an appropriate way for a youth to gain muscle. While heavy weight lifting and bodybuilding exercises are appropriate for adults, a young body is not yet equipped to handle the heavy loads adults can lift. Beginning a serious weightlifting program before your skeletal system has fully developed can leave you vulnerable to injuries that may inhibit your ability to build muscle in the future. A 14-year-old should gain muscle without risking injury.
Train your cardiovascular system with a 10 minute warm-up before any activity. A short jog, jumping jacks or other calisthenics should precede any strength training and will increase your endurance and reduce your chance of injury.
Perform body weight exercises like pushups, situps, pullups and squats as you begin to develop your muscles. Try to perform as many of each exercise as you can, and gradually increase the number you do as you begin to improve.
Lift lighter weights with high numbers of repetitions. For any weightlifting exercise you do, choose a weight that allows you to perform 10 to 15 repetitions over three to four sets. If you cannot perform this many repetitions, use a lighter weight until you gain more strength.
Focus on compound exercises, which are those that incorporate more than one joint movement. These exercises—which include bench press, dead lift and weighted squats—activate more muscle fibers at once, leading to more overall muscle gain in less time. You can begin to focus on isolated muscles after your primary muscles get larger as you get older.
Concentrate on your form as you lift. Many weightlifting injures are caused by poor form, which allows you to "cheat" and lift more weight than your muscles are otherwise ready for. Learning the proper form as a young weightlifter will give you a stronger basis in your later bodybuilding years.
Work out your entire body rather than just concentrating on the showy muscles. Though it may be tempting to focus your workout on your arms and chest, do not neglect the legs and back.
Eat a lot of food. Gaining muscle has as much to do with what you eat as what you lift. While you are young, your metabolism will be at its fastest. It takes a lot of calories to provide you with the nutrients you need to grow your muscles. Eat high-quality, protein-rich foods, and try to have something to eat at least every two hours.
Avoid the temptation to add too many supplements to your diet. While a protein shake is okay, stay away from steroids, growth hormones, synthetic androgens and most other supplements designed to increase your muscle growth unless recommended by a physician.