Part 1: Safety & Benefits
The number of young athletes who are lifting weights as part of their training is steadily increasing. In past years, many discouraged weight training in children and young adolescents. This stemmed, in part, from the fear of injury and adverse effects on growth and development. We now know that properly supervised resistance exercise can have a number of positive effects on sports performance, health and psychological well-being. Recently, the National Strength and Conditioning Association assembled seven of the most prominent researchers in the area of youth fitness and resistance exercise. They reviewed 258 individual research studies and prepared a consensus paper regarding the safety, effectiveness, benefits and design of youth resistance training programs. What follows is a brief summary of the NSCA’s Position Statement. Part 1 focuses on safety issues and benefits of strength training. Part 2 addresses designing safe and effective programs.
Safety: For years, some argued that children should not lift weights as it could stunt their growth and injuries to the growth plates of the long bones. In fact, early surveys of sports-related injuries reported a number of injuries associated with youth weight training. However, the vast majority of these injuries were due to improper technique, poor supervision and unqualified trainers; not to weight lifting per se. In weight training studies that were properly supervised by knowledgeable trainers and the children were taught proper technique, very few, if any injuries occurred. This was the case when kids were using machines, body weight exercises, free weights or plyometrics. The key is that the programs must be properly supervised by qualified trainers that provide proper and constant instruction on the techniques and use of equipment. If this is done, the risk of injury is actually very small. As for growth and stature, no study has shown adverse effects on cartilage or growth plates and there is no evidence of “stunted growth”. In fact, resistance training in both children and adults promotes bone health rather than damage. Based on this, the authors of the Position Statement note that “there are no justifiable safety reasons that preclude children or adolescents from participating in a resistance training program”.
Effectiveness: There is little doubt that resistance training increases strength in children and adolescents. Studies show that children as young as 5-6 years of age can benefit from strength training. The strength gains of young children are usually slightly less than what happens in adolescents and adults but they are impressive none the less. Increases in strength of 30-50% have been reported. A wide variety of programs are effective including weight machines, free weights, medicine balls, elastic bands and body weight exercises.
A key difference between children and adults is how they adapt to resistance training and what is responsible for the strength gains. In adults, most of their strength gain is due to muscle hypertrophy (increased muscle mass). Children lack the testosterone needed to increase muscle size. Most of the strength increase that occurs in children is due to neuromuscular adaptations, improvements in skill, coordination and activation of individual muscle fibers. However, this is not to say that children cannot increase their muscle mass. Changes in muscle size are simply not as great as those that occur in adults.
Benefits: There are many potential benefits of youth resistance training programs for both the athlete and non-athlete. All health professionals agree that exercise is essential for proper growth and development. Almost any fitness program can enhance both physical health.
However, weight training offers several unique benefits that aerobic exercise programs may not. Studies have shown that weight training can improve fitness as well as reduce cardiovascular risk factors, strengthen bone, improve motor skill, increase resistance to sports-related injury and improve psychosocial well-being. For the non-athlete, resistance training has been shown to improve body composition by a combination of fat loss and muscle mass gain. It may also lower risk factors for developing diabetes, combat hypertension and improve other health markers. One advantage of resistance training for the non-athlete is that many children find it more enjoyable than traditional programs that involved prolonged aerobic exercise (e.g. jogging). This is especially true in non-athletes. For this reason, recent research studies promote weight training as a way to combat and treat childhood obesity. The changes in body shape, composition and strength can be a psychological boost. Improvements in self-confidence, self-image, mood and overall psychological well being are all associated with resistance exercise. Thus, weight training can be a very effective way to promote health in children and adolescents.
For any athlete, strength and power are essential elements of many sports. It is clear that weight training can lead to improved sports performance. This is especially true in young athletes. However, the benefits of resistance exercise extend beyond performance on the field. One of the more important payoffs of resistance training is that it increases the resistance to sports-related injuries. Improvements in bone health, neuromuscular coordination and muscular strength all make the young athlete less susceptible to injury. This is critically important for non-contact injuries such as knee and ankle ligament sprains and tears. In fact, one study suggests that a well-designed and properly supervised weight training program may reduce the risk of injury by 15-50%. Again, a wide range of programs ranging from free weights to body weight exercises seem to be effective. Thus the increased resistance to injury may be one of the more important benefits of resistance training. Given the high incidence of injuries in some athletes (e.g. ACL injuries in girls), some type of resistance training should be an essential part of any sports training routine.
Conclusions: Based on their examination of the research pertaining to youth resistance training, the NSCA arrives at seven key conclusions. They state that a properly designed and supervised resistance training program:
1. Is relatively safe
2. Can enhance the muscular strength and power in youth
3. Can improve the cardiovascular risk profile in youth
4. Can improve motor skill performance and may enhance sports performance in youth
5. Can increase a young athlete’s resistance to sports-related injury
6. Can help improve the psychological well-being of youth
7. Can promote and develop exercise habits during childhood and adolescents
Given this information, there is no reason why children and young adolescents should not participate in properly supervised resistance training programs. How these programs should be developed is the subject of Part 2 (coming soon).
Faigenbaum AD, Kraemer WJ, Blimkie CJR, Jeffereys I, Micheli LJ, Nitka M, Rowland TW (2009) Youth resistance training: Updated position statement from the National Strength and Conditioning Association. Journal of Strength and Conditioning Research, 23: (supplement 5) / S60-S79.