In the first instance, the authors contend that it is vital to understand the difference between strength training, weightlifting, powerlifting and bodybuilding. Briefly, strength training uses resistance methods to increase one’s ability to exert or resist force. Weightlifting and powerlifting are competitive sports that contest maximum lifting ability in specific lifts (clean-and-jerk and the snatch in the former; squat, bench press and dead lift in the latter), while bodybuilding is an aesthetic sport that does not involve competitive lifts but depends on weight training. Along with these definitions, Benjamin and Glow state that “many potentially serious injuries reported in the literature are associated with the sports of weightlifting and powerlifting and not with competently supervised strength training programmes”.
Injury risk examined
However, they also report that a retrospective review of injuries associated with weightlifting and weight training in pre-adolescents and adolescents found that both these activities are safer than many other sports. Furthermore, in this study,2 the rate of injury for weightlifting was reported to be even lower than for weight training. The explanation given is that in order to master the complex multi-joint lifts, a supervised, progressive programme must be followed with the continual emphasis on technique.
Yet, according to the American Academy of Pediatrics (AAP) and the American Orthopaedic Society for Sports Medicine (AOSSM), children should avoid weightlifting, powerlifting and bodybuilding until they have reached near physical maturity (Tanner stage 5), since the AAP and the AOSSM believe that “these activities show an increased risk of musculoskeletal injuries and potentially dangerous acute medical events for younger participants”. By contrast, and based upon other research, the National Strength and Conditioning Association (NSCA) supports weightlifting and powerlifting as well as strength training in both children and adolescents. However, the importance of qualified supervision is emphasised.
Arguably, much of the confusion relates not just to injury risk, but also to the confusion surrounding the potential for children to develop muscle strength through any of the aforementioned training methods or disciplines. According to Benjamin and Glow, “the development of muscle strength in children is related to age, body size, previous levels of physical activity and various phases of growth”. Furthermore, they believe that early, possibly flawed studies on strength training in children led to the (mistaken) belief that youth strength training was ineffective. Indeed, this belief was incorporated in the 1983 policy statement from the American Academy of Pediatrics which stated that “pre-pubertal boys do not significantly improve strength or increase muscle mass in a weight training programme because of insufficient circulating androgens”.
In contrast to the findings of these early studies, more recent research reported here indicates that children as young as age six years can improve strength when following age-specific resistance training guidelines. It would appear that increases in neuronal activation, intrinsic muscular adaptations and improvements in motor coordination lead collectively to increases in strength, but not muscle size, pre-puberty. As a consequence of these contemporary studies, the AAP’s policy statement (2001) now reads, “studies have shown that strength training, when properly structured with regard to frequency, mode (type of lifting), intensity, and duration of programme, can increase strength in pre-adolescents and adolescents”.
There would appear to be no long-term studies that have investigated the effects of pre-season resistance training and improved sports performance in children. However, it is thought that appropriately designed and supervised programmes may enhance motor fitness skills (jumping, sprinting) and hence sports performance. Benjamin and Glow note that this view is supported by the American College of Sports Medicine.
Weighing the evidence
When the evidence is reviewed carefully and distinctions are made between supervised and non-supervised programmes, the risk of injury as a result of pre-pubescent weight training (and lifting) appears to be very low; and there are many researched benefits, as listed above. Injuries do occur, but there would appear to be no evidence to indicate that strength training is riskier than simply participating in other commonly advocated sporting or recreational activities. In addition, say Benjamin and Glow: “Parents can be assured that strength training (in moderation) will not have an adverse effect on growth. Training may actually be an effective stimulus for growth and bone mineralisation in children, especially for those at risk for osteopenia and osteoporosis”.
A safe programme
Beginning safely means matching the programme to the child. Prehabilitation of the abdominal and shoulder muscles is recommended to reduce the risk of injury and the emphasis on proper technique is essential. Supervision by trained and qualified adults is necessary at all times. Guidelines have been developed by several organisations and these are provided below.
Youth strength training guidelines:
- Strength training is one part of a well-balanced youth fitness programme.
- Training takes place at least two to three times per week with a minimum of one day’s rest between sessions.
- Training involves all major muscle groups, with a balance between opposing muscle groups.
- Resistance exercises are done through a full range of motion to develop strength while maintaining flexibility.
- Participants are encouraged to maximise their athletic potential by optimising their dietary intake (ie, adequate hydration, proper food choices).
Prehabilitation of the shoulder and torso muscles
- Begin with minimal resistance (body weight against gravity or a bar without added weights) and add weights in 0.5kg increments as needed.
- Work intrinsic shoulder muscles, with special focus on the anterior deltoid, supraspinatus, middle deltoid, posterior deltoid, internal rotators and external rotators.
- Work upper back (scapular stabilising muscles) with resistance exercises, including shoulder shrugs, bent over lateral raises, bent over rows, bench rows, seated rows and latissimus pull-downs.
- Work lower back and abdomen with resistance exercises, including lumbar paraspinous stretching, three-direction crunch sit-ups and reverse sit-ups.
- include adequate warm-up and cool-down stretching in every session.
- Begin with one light set of 10-15 repetitions of 6-8 exercises.
- Encourage success by choosing the appropriate exercises and workload for each child.
- Focus on participation and proper technique rather than the amount of weight lifted.
- Perform 1-3 sets of a variety of single and multiple joint exercises, depending on time, goals and needs.
- When necessary, adult spotters should assist the child in the event of a failed repetition.
- Teach students how to use workout cards and regularly monitor progress.
- Vary the strength training programme over time to optimise training and prevent boredom.
When proper technique is mastered, weight can be added
- If a child cannot do at least 10 repetitions per set with a given weight, the weight is too heavy and should be reduced.
- When 15 repetitions becomes too easy, the next weight increment can be attempted (typically a 5% to 10% increase on average is recommended).
- A child should be able to do three sets of 15 repetitions of a given exercise in three consecutive sessions before more weight is attempted.
References available on request