Training
Articles
Weight Training for Kids: Pt2
by Charles Poliquin
8/24/2011 10:57:45 AM
Yesterday we looked at how resistance training is an excellent exercise choice for kids. Today, I review key issues to be considered in developing a youth program or when you are choosing the best coach for your kids. Available research provides guidance on how to train through growth spurts and the awkward stages of puberty so that kids perform at their best, develop self confidence, and have fun.
1) Vary the Program Part 1: Match Natural Growth Spurts
A main reason youth need distinct programming is that improvement rates are nonlinear based on biological age and there is typically rapid fluctuation in physical performance based on this age. I’m going to present some evidence relating to chronological age, but be aware that children mature at different rates, even within the genders, meaning in a class of 12 year old boys, some will have the physical maturity and corresponding abilities of 11 or 10 year olds, and some will be more like 13 or 14 year olds.
With that in mind, research shows that between the ages of 7 and 17, males go through periods of accelerated physical improvement and decreased performance that follow identifiable age-related trends. These adaptation periods typically occurred before and after the peak growth spurts. In this study, researchers wanted to identify ages when the stretch shortening cycle could be developed to maximize athletic and jumping ability. The stretch shortening cycle occurs when muscles are stretched, as in a quick countermovement motion before jumping on a box, and then contract very quickly, as in the jump onto a box. Training the stretch shortening cycle has been shown to also improve sprinting speed and the ability to explode forcefully off the ground.
The study tested participants in the countermovement vertical jump and squat jump. The data showed gradual increases in squat and countermovement jump height as age progressed, except between ages 11 and 12—there was a temporary decline in performance and jump height at this age. There was a significant improvement in jump height from age 10 to 11, but no other significant improvements between consecutive years (improvement averaged about 5 percent between these consecutive years). Rather, significant improvements were seen when comparing groups by more than three years.
The age groups 10 to 11 and 12 to 13 were identified as periods of accelerated adaptation, and this somewhat larger improvement in performance between 12 and 13 is a compensation for the decrease between 11 and 12. Additionally, ages 15 to 16 were seen as secondary windows of accelerated adaptation. The decrease in performance between ages 11 and 12 is likely due to “adolescent awkwardness,” which is typified by a decline in motor coordination from growth spurts.
The data clearly indicate a gradual, then significant improvement, as children approach puberty, and then a large decrease in performance during the typical ages of growth and maturation. Researchers point to the development of plyometric training programs to maximize the stretch shortening cycle and to help explain potentially disrupted motor development directly before puberty. This information should be communicated to trainees and parents who are concerned about decreases in performance or progress during puberty.
2) Vary the Program Part 2: Training Makes Kids Stronger
One common question is whether resistance training is effective at increasing strength and coordination in youth because of their lack of muscle building hormones such as testosterone. Strength training has been proven to be effective at increasing strength in youth—studies demonstrate increases ranging between 33 and 74 percent.
In terms of absolute strength gains, adolescents (post-puberty) make greater gains in strength than children. For pre-adolescents, gains are due to improvements in neuromuscular strength (specifically motor unit coordination and firing rate)and not to hypertrophic factors because there is not adequate testosterone to stimulate increases in muscle size. The greater gain in strength by post-puberty trainees is likely due to the presence of testosterone and other anabolic hormones. Interestingly, during pre-adolescence there is no evidence of major strength differences between boys and girls who resistance train.
Of course, just like adults, it’s necessary to vary kid’s programs with a wave-like or periodized scheme to produce continued neuromuscular improvements and avoid overuse injuries.
3) Vary The Program Part 3: Avoid Specialization
We know a wave-like, varied program is necessary to make training progress. Equally, having kids play multiple sports or engage in a variety of exercise modes that may include everything from yoga to gymnastics to soccer or tennis to name a few, is preferred to specializing in any one sport or exercise.
Research shows that repetitive motions and excessive stress on muscle and connective tissue, can cause bone and tissue injuries, generally related to overuse. Research into the effects of specialization on young athletes indicates that it can significantly lower overall health, and particularly in female athletes, specialization has been shown to lead to the development of eating disorders or hormonal imbalances.
Additionally, specialization has been shown to cause burnout or boredom in youth athletes. This often leads to early withdrawal from sports and exercise. For example, a 2004 study found that in high-level youth hockey players, those athletes that participated in a higher quantity of training and began training at a younger age had a higher dropout rate than those who spent less time training at younger ages. Another study of elite swimmers found that those who specialized at an earlier age, did not stay on the national team as long, and retired younger than late specializers.
Of course, for gifted athletes, specialization is necessary, and there is evidence that the most successful elite athletes go through three stages of development from diversification to specialization. They typically played a variety of sports during the “sampling years” of 6 to 12, less sports with a tendency towards specialization during the “specializing years” of 13 to 16, and commitment to just one activity during the “investment years” over age 16.
4) Jumping and Plyometrics Are Safe, Fun, and Natural Movements
I’m going to call your attention back to the need to make exercise fun. Kids usually like jumping and will definitely enjoy seeing themselves improve—which they will if they practice. Natural movements are key for developing neuromuscular strength and making it fun—if you watch children on a playground they will run, jump, and skip, and will likely play with balls, practice their balance, and climb if they have the right equipment.
Resistance training can support natural movements—think of squats, overhead presses, low-intensity plyometrics, and throwing exercises with medicine balls. Training can be pleasurable for youth, and once they experience how their bodies can change and that training will support sport performance, they will usually want to work out.
For plyometrics, the NSCA review notes that low-intensity plyos can be included in a training program to enhance biomechanics, improve functional abilities, and decrease sports-related injuries, once base levels of strength and balance are achieved. Researchers suggest that reported injuries to growth cartilage in youth were due to improper lifting techniques or lack of supervision. Also, take note that there appears to be less chance of injury to the growth cartilage in pre-adolescent children than adolescents because the growth cartilage is stronger and more resistant to pounding forces at earlier ages.
5) Keep it Short: Volume Matters
Children have short attention spans and will get the greatest physical development from relatively brief training sessions. This is also the key to programming plyometrics. Youth should have a lower volume of training than adults for jumping and power moves, with fewer foot contacts when doing plyos. Training proper jumping and landing mechanics is key for athletic development and particularly to prepare for sports that include these motions in competition because landing may induce ground reaction forces of up to 5 to 7 times body mass.
Additionally, don’t ignore the amount of recovery time needed for youth after plyos and more advanced training methods—their neuromuscular systems need to be able to adapt to the training stimulus.
6) Resistance Training Helps Prevent Sport-Related Injuries
There is a lack of evidence on pre-adolescents, but research on teenagers supports this. One study of 1837 of Norwegian handball players aged 15 to 17 who performed a resistance training program found a significant protective effect of training on knee and ankle health (48 injuries occurred in the training group of 958 athletes in contrast to 81 in the non-training control group out of 879).
A second study of 1008 soccer players aged 12 to 17 compared a control group with a training group that performed dynamic stretching, eccentric strength training, agility and jumping exercises. The injury rate in the training group was 2 injuries for every 1000 player hours versus 3.35 injuries per 1000 player hours in the non-training control group. Researchers considered this to be a significant decrease in injury rate and recommended the use of a neuromuscular training program for athletes.
Reference #1
Lloyd, R., Oliver, J., Hughes, M., Craig, W. The Influence of Chronological Age on Periods of Accelerated Adaptation of Stretch-Shortening Cycle Performance in Pre and Postpubescent Boys. Journal of Strength and Conditioning Research. July 2011. 25(7), 1889-1897.
Reference #2
Faigenbaum, A., Kraemer, W., Blimkie, C., Jeffreys, I., et al. Youth Resistance Training: Updated Position Paper from the National Strength and Conditioning Association. Journal of Strength and Conditioning Research. 2009. 23(Suppl 5) S60-S79.
References #3
Committee on Sports Medicine and Fitness. Intensive Training and Sports Specialization in Young Athletes. Pediatrics. July 2000. 106(1), 154-157.
Wiersma, L. Risks and Benefits of Youth Sport Specialization: Perspectives and Recommendations. Pediatric Exercise Science. 2000. 12(1), 13.
Cote, J., Baker, J., Abernathy, B. From Play to Practice: A Developmental Framework for the Acquisition of Expertise in Team Sport, in J. Starks and K. Ericsson (eds). Recent Advances in Research and Sport Expertise. 2003. Champaign, IL: Human Kinetics, 89-114.
Thomas, J., Cote, J., Deakin, J. Youth Sport Programs: An Avenue to Foster Positive Youth Development. Physical Education and Sport Pedagogy. February 2005. 10(1), 19-40.
Reference #4
Faigenbaum, A., Kraemer, W., Blimkie, C., Jeffreys, I., et al. Youth Resistance Training: Updated Position Paper from the National Strength and Conditioning Association. Journal of Strength and Conditioning Research. 2009. 23(Suppl 5) S60-S79.
Reference #5
Malina, R. Weight Training in Youth-Growth, Maturation, and Safety: An Evidence-Based Review. Clinical Journal of Sports Medicine. November 2006. 16(6), 478-487.
Reference #6
Emery, C., Meeuwisse, W. The Effectiveness of a Neuromuscular Prevention Strategy to Reduce Injuries in Youth Soccer: A Cluster-Randomized Controlled Trial. British Journal of Sports Medicine. June 2010. 44(8), 555-562.