Effects of Strength Training in Preadolescents and Adolescents

1. Effects of Strength Training in Preadolescents and Adolescents Presented by Alecia Pollard

2. Introduction • Muscle strength development in preadolescents and adolescents has been debated topic for the last couple of decades among health professionals, parents, and coaches. • How much training? • How soon?

3. Strength Training • Definition – also known as weight training or resistance training. Using resistance methods to increase one’s ability to exert or resist force. • Free weights, machines, the individuals own weight, or other devices (e.g. elastic bands, medicine balls) provide resistance.

4. Early Studies Cast Doubt • Strength gains would neither benefit performance nor reduce the risk of injury in the children’s sports. • Resistive weight training is dangerous for children because it carries an unacceptable risk of injury.

5. Cont. • 1978, study by Vrijens, reported the results of an 8-week resistance training program done 3x/week by boys. • Preadolescents were incapable of increasing strength • However, the adolescents increased strength in all muscle groups tested. • A decade later, Docherty et al reported that 12-year old boys did not benefit from 3 session per week in a 4-6 week strength program following their competitive season • **These studies involved low resistance with one 1-2 sets of exercises per session, which may not have produced measurable results.

6. Meta-analysis of strength training in children indicate that many studies are flawed by poor methodology. • Children continue to grow as they progress through adolescence and demonstrate natural increases in strength • Any research to examine strength gains in a child must incorporate an adequate control group to account for natural growth. • In addition, the design of the training program is very important. • The studies previously cited, low-intensity training volume and short-duration study protocols probably led to inherently flawed result.

7. Bone and Growth Development • Changes and adaptations occur in bone and muscles • External and internal factors can affect the structure composition of the bone • Weight bearing physical activity plays an important role in bone development • Bone mineral density reaches about 90% of its peak by the end of the second decade

8. Cont. • Studies stated the importance of regular exercise during this period helps to optimize bone development and prevent osteoporosis later in life

9. Injury Occurrences • The US Consumer Product Safety Commission, through its National Electronic Injury Surveillance System (NEISS), had estimated the number of injuries that are associated with strength training equipment. 1991-1996 = 20,940 to 26,120 injuries occurred each year under the age of 21 • NEISS data did not specify the cause of injury or whether if was from recreational or competitive weight lifting injuries

10. Injuries Cont. • Muscle strains account for most of all injuries • 40-70% • Lumbar back is the most commonly injured area • Followed by the knees, chest, shoulders, and elbows • Fractures were the most common serious injuries • A limited number of case reports raised concern about epipyseal injuries in the wrist and apophyseal injuries in the spine from weight lifting in skeletally immature individuals. • These injuries were stated to be known as uncommon and are believed to be largely preventable by avoiding improper lifting techniques, maximal lifts, and improperly supervised lift.

11. Injury Prevention • Proper technique and lifting mechanics at all times • Preadolescents or adolescents should begin a strength training program with low-resistance exercises until proper technique is learned. • Supervision!!! • ACSM, AAP, AOSSM, and NSCA, now support children’s participation in appropriately designed and competently supervised strength training programs

12. Study I • 1999, this study compared the effects of a low repetition-heavy load resistance training program to a high repetition-moderate load resistance training program, and the control group did not exercise • Results showed a significant increase in both of the exercise groups compared to the control group • Differences between the 2 exercise groups showed that the high repetition loading had a greater result on the leg extensions machine for the muscular endurance test • The high repetition loading group was the only group that had significant results on the chest press for the 1RM and the muscular endurance test

13. Study II • 1990, this study looked at the effects of a 20-week high intensity progressive training on maximal voluntary strength, evoked contractile properties, muscle cross-sectional area, and motor unit activation in preadolescent boys • The experimental group trained for 3x week for 20 weeks doing circuit training under adult supervision • Results confirmed that resistance training wih this age group showed that they are capable of making strength gains following appropriate resistance training programs • Everything measured increased except for there was no significant effects of training on any of the cross-sectional areas and no significant differences in body composition

14. Study III • Performing a 1-RM with preadolescence is to some observers unsafe and may be inappropriate or potentially injurious to children • Other concerns are that this method of testing may cause structural damage to the developing musculoskeletal system • This study evaluated the safety of the 1-RM strength testing in children and they assesed its practical application as a testing tool in this age group (6-12 years old) • Results from this study indicated no abnormal responses to or injury from 1-RM testing

15. How much and How Soon? • **This depends on an individual basis of each child • Most of the studies said that 3x week, with a day of rest inbetween • Progressive resistance exercises require successful completion of around 8-15 repetitions in good form before increasing weight or resistance • Research states that children as young as age 6 can improve strength when following age-specific resistance training guidelines

16. Conclusion • Guidelines and preventative measures (proper form and supervision!) to avoid injury while strength training was the most common recommendation from all of the studies • A properly designed and supervised youth training program is most important when beginning training as a preadolescent or adolescent • Adult strength guidelines should not be imposed on a child who is anatomically, physiologically, or psychologically less mature

17. Cont. • Conclusive observations form all the studies suggest that preadolescent and adolescent years are important for bone and muscle development • 1-RM testing in this age group is safe and effective ONLY if administered by a qualified health professional to avoid injury and improper lifting mechanics

18. References • Benjamin, H., Glow, K. (2003) Strength Training for Children and Adolescents. The Physician and Sportsmedicine. 31:9 • Eliakim, A., Beyth, Y. (2003) Exercise Training, Menstrual Irregularities and Bone Development in Children and Adolescents. Journal of Pediatric and Adolescent Gynecology. 16:4-201 • Faigenbaum, A., Milliken, L., Westcott, W. (2003) Maximal Strength Testing in Healthy Children. Journal of Strength and Conditioning Research. 17:1-162 • Faigenbaum, A., Westcott, W., LaRosa, R., Long, C. (1999) The Effects of Different Resistance Training Protocols on Muscular Strength and Endurance Development in Children. Pediatrics. 104:1-5 • Frappier, J. (1999) Training Through puberty. Research and Development – Frappier Acceleration. 3:1-1 • Hawkins, D., Metheny, J. (2001) Overuse Injuries in Youth Sports: Biomechanical Considerations. Medicine and Science in Sports and Exercise. 33:10-1701 • Jones, A., Maffulli, N. (2002) Intensive Training in Elite Young Female Athletes: Effects of Intensive Training on Growth and Maturation Are Not Established. British Journal of Sports Medicine. 36:1-13 • Newland, H. (2001) Strength Training by Children and Adolescents. Pediatrics. 107:6-1470 • O’neill, D. (1989) Preventing Injuries in Young Athletes. The Journal of Musculoskeletal Medicine. 6:11-21 • Ramsay, J., Blimkie, C., Smith, K., Garner, S., Macdougall, J., Sale, D. (1990). Strength Training Effects in Prepubescent Boys. Medicine and Science in Sports and Exercise. 22:5-605 • Risser, W. (1991) Weight-training Injuries in Children and Adolescents. American Family Physician. 44:6-2104