My son has not yet entered puberty and he loves to play hockey. He wants to get stronger and asked me to take him to the gym for strength training sessions. Is this safe at such a young age? I am concerned it may limit his height. Should I be?
Strength training, also known as resistance training, is done to enhance muscle size and strength. It may involve the use of free weights, such as dumb bells; it may also include the use of weight machines commonly found in both homes and commercial gyms. For some families who want to use less expensive methods, elastic tubing may be an option or even the use of body weight itself (e.g., lifting a partner or one's own body weight).
Some athletes use strength training as a form of cross-training, for example to stay in shape for their regular sport during the off season. Or athletes may use it as part of a rehabilitation program when recovering from a sports injury. There is currently no scientific evidence to indicate that strength training helps to prevent sport-related injuries. It also does not enhance running speed or jumping abilities, activities used during sports such as basketball.
In sports such as football and hockey, where strength and power may enhance an athlete's performance, strength training may have an important role. There is some evidence that it may actually enhance the muscle enlargement that normally occurs during pubertal growth. This is due to an increase in the number of motor neurons that "fire" with each muscle contraction.
During adolescence, strength training may be done to improve the size and definition of muscles. It does not slow down linear growth and is unlikely to cause any negative effect on a child's height, provided there is no use of anabolic steroids or body-building supplements.
Because the majority of pre-adolescent children are skeletally immature, some experts have raised concerns regarding the risk of epiphyseal injuries of the growth plate area. But according to references in a recent statement by the American Academy of Pediatrics' committee on Sports Medicine and Fitness (Pediatrics, April 2008), this is not a common concern. In fact, such injuries are more likely to happen when there is no supervision of a young athlete or when the youngster lifts excessive amounts of weights.
The most common injuries due to resistance training are strained muscles, with most of the injuries occurring in the back area. When an athlete warms up and cools down gradually, the risk of such an injury is greatly diminished. In patients who have high-normal or abnormally high blood pressure, resistance training may not be wise; it may in fact elevate the blood pressure further.
Experts in pediatric sports medicine suggest strength training be started with low resistance exercises, at least until the athlete has learned proper methods and techniques. The number of repetitions should vary from 8 to 15 at first, and then more weight can be added gradually in 10% increments. The duration of the workouts should be limited to 30 minutes maximum, and the frequency in one week should not exceed 3 times. There are no additional benefits when a child engages in resistance training more than 4 times per week.
Gains in strength, power and muscle size are usually lost after 6 weeks if resistance training is discontinued. It is also wise to combine it with aerobic training, as opposed to only lifting weights. At the annual conference of the Obesity Society held in Boston in 2006, data was presented showing that strength training in obese adolescents is more likely to be sustained over time than aerobic training.
The American Academy of Pediatrics, with regard to their recommendations about strength training in children, concludes that:
- It is safe and effective as long as precautions are followed.
- Competitive weight lifting and power lifting must be avoided.
- A strengthening program should include all major muscle groups.
- Any sign of injury due to strength training should be evaluated by an expert, such as a physiotherapist or a pediatric sports medicine doctor.
In Calgary, there are only a handful of trained pediatric sports medicine experts –Dr. Eric Babins works in the south and Dr. Neil Cooper works in the north.
For more information, read the book Sport Success Rx, authored by a Sports Medicine Pediatrician and an Olympic Physician, Dr. Paul R. Stricker, M.D. This book provides a full chapter on the topic of strength training for young athletes.
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An informed parent is ... an empowered parent.