iStock_000015975110XSmallI still remember when I was 13 and doing my first barbell squat. I felt like the female version of Arnold Schwarzenegger on muscle beach. Yet, when I shared my achievement with my parents they were worried about me harming my spine and bone mass.

Twenty five years after that initial barbell squat, I am now strength and conditioning coach, and still find many parents facing the same concern as mine. But does early age resistance training really present a problem for a growing teen’s muscles and bones?

While parents’ concern deserves attention, coaches and trainers have learned that adolescent’s bodies are not simply small versions of adults.

“During growth spurts, the body changes rapidly and this can especially affect the musculoskeletal system,” says Nick DiNubile, orthopaedic surgeon specializing in sports medicine and author of FrameWork-Your 7 Step Program for Healthy Muscles, Bones & Joints.Muscle/tendon imbalances can occur because bone can grow faster than the surrounding muscles and tendons. The result can be tight muscle groups and some imbalances that predispose to certain injuries and orthopedic conditions, like low back pain, patellar pain syndrome and hamstring pulls.”

Also, a growing body is influenced by gender, he says. “The female frame goes thru some additional changes too, such as widening of the pelvis, and other alignment issues, which can set them up for additional hip and knee problems.”

But just like adults, active teens cannot afford to overlook stretching the muscles—mostly the hamstrings, lower back, and calf muscles—nor strengthening the core (lower back-abdominal-hip muscles) for overall body stabilization.

Critical Bone Mass Timing

One area that parents worry the most during growth spurts is the skeleton. Do jumping, running, and/or skipping affecting the growing teen’s spine? Are resistance squat exercises even safe for a 13 year old?

The answers: It’s not only safe, but also necessary.

“Exercise is important in building better bones and the best type is weight bearing exercises where loads are being applied to the muscles and skeleton,” says DiNubile. “And the best overall weight bearing exercise is weight training.”

Activities like running build bones in the lower body, but do nothing for the upper body or mid and upper spine. Swimming and cycling are great for the heart and overall health, but will not build bones.

iStock_000015558074XSmallBut together, they can provide the best results. Weight training exercises along with high impact exercises—basketball, tennis, gymnastic, among others—have shown to increase bone mass in the lumbar spine and lower limbs, as well as improve muscles growth. And larger muscles develop greater forces in the bones to which they are attached.

So for proper bone health, kids need to be active, but they also need to begin at a young age. A study that looked at the effect of later bone health from moderate and vigorous physical activity at an early age found that “kids who are less physically active at an early age my lose out on the opportunity to obtain the highest peak bone mass possible later in life when they are likely to be less active,” concludes the article, “Early Physical Activity Provides Sustained Bone Health Benefits Later in Childhood,” published in Medicine & Science in Sports & Exercise.

Knees at Risk—For Girls

If there is one risk for active kids it is with the knees, especially among girls. “Serious knee injuries are occurring at epidemic rates,” says DiNubile.

Why is this mostly a female problem? It is because the ligament responsible to stabilize the center of the knee, the ACL, is five to seven times more likely to tear in females. “This is especially true in quick start/stop running/cutting and jumping sports like basketball, soccer and volleyball,” says DiNubile.

There are other causes too that contribute to female knee problems: a wider pelvis and thus more knocked-knee postures, and weaker muscles compared to boys. In fact, a recent study shows that leg muscle imbalance—quadriceps stronger than hamstrings, and front leg muscles stronger than back leg muscles—combined with increased knee instability during the adolescent growth spurt in girls may contribute to a decrease knee stability during landing, which increases the risk of knee injury.

“At the age of puberty, girls start to land differently from a jump—either more straight legged or the knee shifts inward—than boys, making ACL tears much more likely,” says DiNubile. The good news is that there are preventive programs (that every young athlete, especially females) should do that re-train the “landing gear.” including jump/landing training, agility and core strength enhancement.”

How to Lift Weights Right

While DiNubile believes most children can safely do strength training, they still should be supervised. Specially, they need to avoid the tendency to “see who is the strongest,” which can set up him or her for an injury. Instead, make sure your kid focuses on proper technique. A trainer should have them begin with their own weight with tubing and then progress to free weights and machines. Make sure the workouts target all major muscles of the upper body, lower body, and the core, and from all muscles sides (front and the back) to prevent imbalance. And don’t forget that girls may need extra help to land properly, so jump squats and agility drills should be included in routines—but make sure the trainer teaches her proper landing techniques.

There’s no need for your kid to be at the gym every day. Two to three sessions a week is advised. Keep in mind that exploring different sports and activities is the best way to lessen the risk of injuries and maintain their motivation.

And as kids grows stronger so will their self-esteem. A recent study shows that kids with higher muscular fitness report excellent perceived health status, very good family relationships, and academic performance, according to an article published in the Journal of Strength and Conditioning Research.


Special Contribution:

Dr. DiNubile is an Orthopaedic Surgeon specializing in Sports Medicine in private practice in Havertown, Pennsylvania. He is the author of the bestselling book, FrameWork- Your 7 Step Program for Healthy Muscles, Bones & Joints and also the FrameWork “Active For Life” book series. He is Executive Producer and host of the award winning national PBS television special, Your Body’s FrameWork and has served as Orthopaedic Consultant to the Philadelphia 76ers Basketball Team and Pennsylvania Ballet for many years. He is the Chief Medical Officer for The American Council on Exercise (ACE) and Vice-President of the American Academy of Anti-Aging Medicine (A4M). Dr DiNubile has been consistently chosen in “Best Doctors in America” and is also named a US News & World Report “Top Doctor.” He has been featured on Good Morning America, The Today Show, CNN, HBO Real Sports, National Public Radio, and in the New York Times, the Wall Street Journal, the Washington Post, Newsweek, and numerous other publications. He is one of the most quoted doctors in America. His website, is a trusted source of health and wellness information. Follow DrNick on Twitter @DrNickUSA