465
Growth Dynamics in the Context of Pediatric Sports Injuries and Overuse Ernst B. Zwick, MD, PD1
Robert Kocher, MD2
1 Department of Pediatric Orthopedic, Private Practice, Graz, Austria 2 Private Practice, Judenburg, Austria
Address for correspondence Ernst B. Zwick, MD, PD, Petrifelderstrasse 13, 8042 Graz, Austria (e-mail: offi[email protected]).
Abstract
Keywords
► youth sports ► growth velocity ► injury
The onset and timing of the growth of children and adolescents occurs with considerable variability in cohorts of the same chronological age. The musculoskeletal system changes in proportion over time, and lever-arm changes, altered individual flexibility, and strength lead to age-specific injury patterns in youth sports. In sports, juniors are commonly grouped according to their chronological age. Early- and late-maturing children and adolescents might therefore not routinely be trained in relation to their biology. This not only represents a risk for overuse and injury but might limit their development in sports. To obtain information about the biological age of children is challenging. Numerous methods have been studied and validated. However, the implementation of these methods on a large scale is still to come. This report provides a brief overview of growth dynamics in relation to youth sports injuries and describes a few challenges for the future.
Youth interest in sports participation has increased over the past 15 years. Along with this increase, sports injuries are on the rise in the pediatric population.1 A major proportion of all injuries in children and adolescents are sports related.2–4 The National SAFE KIDS Campaign reported that 3.5 million children experience an injury by participating in recreational activities or sports every year.5 Of all sports-related injuries, chronic injuries and overuse represent up to 54% in youth sports.6,7 The group of young athletes between the ages of 10 and 14 appear to be especially prone to injury and overuse.8–10 Risk factors for sports injuries are commonly divided into intrinsic and extrinsic factors. Extrinsic factors such as training load, competition load, and equipment, and intrinsic factors like psychological factors, previous injury, or a previous history of physical conditioning are equally important in the context of youth sports injuries. However, because this article focuses on the growth dynamics of children and adolescents in the context of sports injuries, growth-related factors are discussed predominantly.
Issue Theme Sports Injuries and Imaging in Children; Guest Editor, Erich Sorantin, MD, PhD
Growth Dynamics in Childhood and Adolescence Growth and development occur at individual rates and are regulated genetically, hormonally, and by environmental and epigenetic factors.11,12 When evaluating growth progression, height and body mass increase markedly in the preadolescent and adolescent years. Girls reach their peak height velocity (PHV) at 12 years of age, boys at 14 years on average.13,14 Gains in total height are composed of increases in the length of different body parts growing at different speeds. Looking at changes in stature or total height, it is important to note that the maximum growth speed of the legs occurs before maximum increases in sitting height.15 Foot size reaches maximum growth velocity for girls and boys even 1.8 and 2.3 years before PHV, respectively.16 Adding to this complexity, the timing of PHV underlies secular trends and can vary considerably in collectives of healthy children.17,18 Skeletal growth dynamics are related to chronological age (CA), but an early
Copyright © 2014 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1389263. ISSN 1089-7860.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Semin Musculoskelet Radiol 2014;18:465–468.
Growth Dynamics in Pediatric Sports Injuries
Zwick, Kocher
or late onset of pubertal growth spurt represents variations of the norm. It was the correlation of longitudinal height velocity data and secondary sex characteristics that led to the convenient definition that children 2 standard deviations above or below the average PHV should be referred to as early or late maturing, respectively.19 Using an age-dependent classification, girls reaching PHV at the age of 11 and boys at the age of 13 would be classified as early maturing. Girls and boys who attain PHV after 13 and 15 years of age, respectively, would be classified as late maturing.14 In various parts of the world, the growth spurts of children and adolescents seem to differ. Comparing published data from various sources, PHV is reported to vary regionally. Depending on the region, the time of maximum growth velocity occurs in girls between the ages of 10.8 and 12.2 and in boys between 13.3 and 14.4 years of age.20–23
Growth-Related Changes of the Skeletal System Bone mineral density (BMD) is lowest before the onset of PHV, and bone strength follows after increases in lean body mass during puberty.24,25 So one might argue that within a certain time window young people have to deal with relatively long lever arms and a low BMD. When long bones reach their fastest rate of growth before PHV and gains in lean body mass precede increases in bone strength, skeletal mechanics might therefore be set up for injury and overuse. Growth cartilage is less resistant to injury than mature bone.26 Because increases in lever-arm length occur while growth plate thickness is on the decline, torsional stresses at the growth plate are less well tolerated. Also, the length of the long bones increases before gains in length of the muscle-tendon complex.27,28 Muscular imbalances might therefore represent a temporal physiologic phenomenon because soft tissue tension and relative strength are factors that stimulate length gains in skeletal muscles.2,29 Joint cartilage stiffens during maturation at rates that currently are unknown in detail.30 Longer lever arms, an increasing lean body mass, and possible muscular imbalances might bear risks when the joint cartilage of junior athletes gets heavily loaded.
Age-Specific Risk Factors Intrinsic and extrinsic risk factors in youth sports change with age. Training volume and intensity commonly increases according to training age. Also, injury patterns could be attributed to age-specific changes in body composition. Normal changes in somatic growth could pose an intrinsic risk in adolescent sports. It is documented that sports injuries and overuse show distinct age-related patterns. 31 Avulsion fractures, Osgood-Schlatter disease, distal radius fractures, or osteochondral lesions are typical sports injuries of youth athletes showing age-related incidences ( ►Fig. 1). 32–37 However, there is still a lack of scientific evidence to clarify relations between specific ages and certain types of sports injuries. Seminars in Musculoskeletal Radiology
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Fig. 1 Growth velocity changes over time represent a typical wavelike shape. The pubertal growth spurt brings about several changes in body composition. Increases in lever-arm lengths of the legs and arms, a relatively low bone mineral density, and changes in strength and flexibility are intrinsic factors for youth sports injuries and overuse. Typical sports injuries of older children are displayed in relation to the pubertal growth sport.
Prevention The prevention of injuries is one of the main motivations for researchers in the field of pediatric sports medicine and sports science.38–43 Although some issues in prevention are sport specific, the vast majority of reports relate to physical fitness aspects. Age-appropriate training and conditioning of junior athletes is one of the biggest challenges for trainers, coaches, and administrators today.44–47 Most youth sports programs worldwide are currently aligned to CA. Although most young athletes are served well by this approach, earlyor late-maturing children and adolescents run the risk of getting overstrained or being underchallenged. It seems obvious that training and conditioning of children and adolescents should be individualized to meet their very individual needs during growth and maturation.
The Biological Age in Youth Sports Historically, the design of training programs for youth athletes was mainly aligned to CA. There is increased concern that this approach constitutes an extrinsic factor in pediatric sports injuries.48 Methods to estimate or determine the biological age of junior athletes are not commonly available today. Skeletal age (SA) determined by the interpretation of radiographs and developmental age (DA), obtained from anthropometric measurements and the assessment of sex characteristics, have not yet been implemented on a large scale in youth sports. Reasons for the limited implementation of SA and DA were described in a recent review by Lloyd et al.48 An approach to estimate the biological age of junior athletes by evaluating individual growth velocity dynamics bases on repeated measurements of stature is currently under investigation.49
Future Challenges in the Field of Youth Sports Injuries Understanding growth dynamics is a prerequisite when dealing with sports injuries in children and adolescents.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
466
7
8
9
Fig. 2 The rate of change of biological age over time represents an interesting aspect of growth and development. A late-developing child is displayed to catch up with her chronological age. During a time period of 1.5 years, biological age catches up from being 2 years younger than the chronological age at the age of 8 to just 1.2 years younger at the age of 9.5. Catch-up phenomena are one of the reasons for repeated assessments of growth and development at short time intervals (unpublished data from reference49).
10
11 12
13
Because of the variability of growth spurt timing, the assessment and tracking of growth is required for each athlete. Any solution to estimate or determine the biological age of junior athletes should therefore be practicable in the youth sports setting. Any measurements required should be simple enough to enable families, coaches, or trainers to perform them regularly. Time intervals between assessments should be kept short to identify the onset of growth changes early. When comparing biological age and chronological age, differences vary over time. A late-maturing child might catch up with his or her CA in quite a short time (►Fig. 2). Training and conditioning of youth athletes should honor their individual biological age. This requires coaches and trainers to group children and adolescents according to their biological age rather than to their CA. Research on youth sports injuries should report findings in relation to the biological age or DA of the cohort studied. Most studies in the field still report on groups of children defined by their CA.
References 1 Gottschalk AW, Andrish JT. Epidemiology of sports injury in 2
3
4
5
6
pediatric athletes. Sports Med Arthrosc 2011;19(1):2–6 Hawkins D, Metheny J. Overuse injuries in youth sports: biomechanical considerations. Med Sci Sports Exerc 2001;33(10): 1701–1707 Valerio G, Gallè F, Mancusi C, et al. Pattern of fractures across pediatric age groups: analysis of individual and lifestyle factors. BMC Public Health 2010;10:656 Damore DT, Metzl JD, Ramundo M, Pan S, Van Amerongen R. Patterns in childhood sports injury. Pediatr Emerg Care 2003; 19(2):65–67 Safe Kids Worldwide. Coaching our kids to fewer injuries: a report on youth sports safety. Available at: http://www.safekids.org/ sites/default/files/documents/ResearchReports/Coaching%20Our %20Kids%20to%20Fewer%20Injuries%20A%20Report%20on% 20Youth%20Sports%20Safety%20-%20April%202012.pdf. Accessed on October 3, 2014 DiFiori JP, Benjamin HJ, Brenner JS, et al. Overuse injuries and burnout in youth sports: a position statement from the American
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Medical Society for Sports Medicine. Br J Sports Med 2014;48(4): 287–288 Luke A, Lazaro RM, Bergeron MF, et al. Sports-related injuries in youth athletes: is overscheduling a risk factor? Clin J Sport Med 2011;21(4):307–314 Kraus T, Švehlík M, Singer G, Schalamon J, Zwick E, Linhart W. The epidemiology of knee injuries in children and adolescents. Arch Orthop Trauma Surg 2012;132(6):773–779 Fridman L, Fraser-Thomas JL, McFaull SR, Macpherson AK. Epidemiology of sports-related injuries in children and youth presenting to Canadian emergency departments from 2007-2010. BMC Sports Sci Med Rehabil 2013;5(1):30 Shah SS, Rochette LM, Smith GA. Epidemiology of pediatric hand injuries presenting to United States emergency departments, 1990 to 2009. J Trauma Acute Care Surg 2012;72(6): 1688–1694 Malina RM. Physical growth and biological maturation of young athletes. Exerc Sport Sci Rev 1994;22:389–433 Hochberg Z, Feil R, Constancia M, et al. Child health, developmental plasticity, and epigenetic programming. Endocr Rev 2011; 32(2):159–224 Beunen G, Malina RM. Growth and physical performance relative to the timing of the adolescent spurt. Exerc Sport Sci Rev 1988; 16:503–540 Malina RM, Bouchard C, Bar-Or O. Growth, Maturation, and Physical Activity. 2nd ed. Champaign, IL: Human Kinetics; 2004 Beunen G. Adolescent Growth and Motor Performance: A Longitudinal Study of Belgian Boys. Champaign, IL: Human Kinetics; 1988 Busscher I, Kingma I, Wapstra FH, Bulstra SK, Verkerke GJ, Veldhuizen AG. The value of shoe size for prediction of the timing of the pubertal growth spurt. Scoliosis 2011;6(1):1 Freitas D, Malina RM, Maia J, et al. Short-term secular change in height, body mass and Tanner-Whitehouse 3 skeletal maturity of Madeira youth, Portugal. Ann Hum Biol 2012;39(3): 195–205 Malina RM, Peña Reyes ME, Chavez GB, Little BB. Secular change in height and weight of indigenous school children in Oaxaca, Mexico, between the 1970s and 2007. Ann Hum Biol 2011; 38(6):691–701 Tanner JM, Whitehouse RH. Clinical longitudinal standards for height, weight, height velocity, weight velocity, and stages of puberty. Arch Dis Child 1976;51(3):170–179 Berkey CS, Dockery DW, Wang X, Wypij D, Ferris B Jr. Longitudinal height velocity standards for U.S. adolescents. Stat Med 1993; 12(3–4):403–414 Largo RH, Prader A. Pubertal development in Swiss girls. Helv Paediatr Acta 1983;38(3):229–243 Largo RH, Prader A. Pubertal development in Swiss boys. Helv Paediatr Acta 1983;38(3):211–228 Gerver WJ, de Bruin R. Growth velocity: a presentation of reference values in Dutch children. Horm Res 2003;60(4):181–184 Faulkner RA, Davison KS, Bailey DA, Mirwald RL, Baxter-Jones AD. Size-corrected BMD decreases during peak linear growth: implications for fracture incidence during adolescence. J Bone Miner Res 2006;21(12):1864–1870 Jackowski SA, Faulkner RA, Farthing JP, Kontulainen SA, Beck TJ, Baxter-Jones AD. Peak lean tissue mass accrual precedes changes in bone strength indices at the proximal femur during the pubertal growth spurt. Bone 2009;44(6):1186–1190 Robertson W, Kelly BT, Green DW. Osteochondritis dissecans of the knee in children. Current Opinion in Pediatrics 2003;15:38–44 Dalton SE. Overuse injuries in adolescent athletes. Sports Med 1992;13(1):58–70 Philippaerts RM, Vaeyens R, Janssens M, et al. The relationship between peak height velocity and physical performance in youth soccer players. J Sports Sci 2006;24(3):221–230
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Growth Dynamics in Pediatric Sports Injuries
Growth Dynamics in Pediatric Sports Injuries
Zwick, Kocher
29 Gossman MR, Sahrmann SA, Rose SJ. Review of length-associated
39 Franklin CC, Weiss JM. Stopping sports injuries in kids: an over-
changes in muscle. Experimental evidence and clinical implications. Phys Ther 1982;62(12):1799–1808 Williams GM, Klisch SM, Sah RL. Bioengineering cartilage growth, maturation, and form. Pediatr Res 2008;63(5):527–534 Stracciolini A, Casciano R, Levey Friedman H, Meehan WP III, Micheli LJ. Pediatric sports injuries: an age comparison of children versus adolescents. Am J Sports Med 2013;41(8):1922–1929 Kessler JI, Nikizad H, Shea KG, Jacobs JC Jr, Bebchuk JD, Weiss JM. The demographics and epidemiology of osteochondritis dissecans of the knee in children and adolescents. Am J Sports Med 2014; 42(2):320–326 Vandervliet EJ, Vanhoenacker FM, Snoeckx A, Gielen JL, Van Dyck P, Parizel PM. Sports-related acute and chronic avulsion injuries in children and adolescents with special emphasis on tennis. Br J Sports Med 2007;41(11):827–831 Yashar A, Loder RT, Hensinger RN. Determination of skeletal age in children with Osgood-Schlatter disease by using radiographs of the knee. J Pediatr Orthop 1995;15(3):298–301 Bailey DA, Wedge JH, McCulloch RG, Martin AD, Bernhardson SC. Epidemiology of fractures of the distal end of the radius in children as associated with growth. J Bone Joint Surg Am 1989;71(8):1225–1231 Rossi F, Dragoni S. Acute avulsion fractures of the pelvis in adolescent competitive athletes: prevalence, location and sports distribution of 203 cases collected. Skeletal Radiol 2001;30(3):127–131 Abalo A, Akakpo-numado KG, Dossim A, Walla A, Gnassingbe K, Tekou AH. Avulsion fractures of the tibial tubercle. J Orthop Surg (Hong Kong) 2008;16(3):308–311 Hoang QB, Mortazavi M. Pediatric overuse injuries in sports. Adv Pediatr 2012;59(1):359–383
view of the last year in publications. Curr Opin Pediatr 2012;24(1): 64–67 Greiwe RM, Saifi C, Ahmad CS. Pediatric sports elbow injuries. Clin Sports Med 2010;29(4):677–703 Demorest RA, Landry GL. Prevention of pediatric sports injuries. Curr Sports Med Rep 2003;2(6):337–343 Flynn JM, Lou JE, Ganley TJ. Prevention of sports injuries in children. Curr Opin Pediatr 2002;14(6):719–722 Emery CA. Injury prevention and future research. Med Sport Sci 2005;49:170–191 Carvalho HM, Coelho-e-Silva MJ, Eisenmann JC, Malina RM. Aerobic fitness, maturation, and training experience in youth basketball. Int J Sports Physiol Perform 2013;8(4):428–434 Carvalho HM, Silva MJ, Figueiredo AJ, et al. Predictors of maximal short-term power outputs in basketball players 14-16 years. Eur J Appl Physiol 2011;111(5):789–796 Figueiredo AJ, Coelho E Silva MJ, Cumming SP, Malina RM. Size and maturity mismatch in youth soccer players 11- to 14-years-old. Pediatr Exerc Sci 2010;22(4):596–612 Maffulli N, Longo UG, Spiezia F, Denaro V. Sports injuries in young athletes: long-term outcome and prevention strategies. Phys Sportsmed 2010;38(2):29–34 Lloyd RS, Oliver JL, Faigenbaum AD, Myer GD, De Ste Croix MB. Chronological age vs. biological maturation: implications for exercise programming in youth. J Strength Cond Res 2014;28(5): 1454–1464 Zwick EB, Leistritz L, Kocher R. Coaching junior golfers based on growth velocity estimates. In: Crews D, Lutz R, eds. Science and Golf V, Phoenix. Energy in Motion: Mesa, AZ; 2008
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Growth Dynamics in the Context of Pediatric Sports Injuries and Overuse Ernst B. Zwick, MD, PD1
Robert Kocher, MD2
1 Department of Pediatric Orthopedic, Private Practice, Graz, Austria 2 Private Practice, Judenburg, Austria
Address for correspondence Ernst B. Zwick, MD, PD, Petrifelderstrasse 13, 8042 Graz, Austria (e-mail: offi[email protected]).
Abstract
Keywords
► youth sports ► growth velocity ► injury
The onset and timing of the growth of children and adolescents occurs with considerable variability in cohorts of the same chronological age. The musculoskeletal system changes in proportion over time, and lever-arm changes, altered individual flexibility, and strength lead to age-specific injury patterns in youth sports. In sports, juniors are commonly grouped according to their chronological age. Early- and late-maturing children and adolescents might therefore not routinely be trained in relation to their biology. This not only represents a risk for overuse and injury but might limit their development in sports. To obtain information about the biological age of children is challenging. Numerous methods have been studied and validated. However, the implementation of these methods on a large scale is still to come. This report provides a brief overview of growth dynamics in relation to youth sports injuries and describes a few challenges for the future.
Youth interest in sports participation has increased over the past 15 years. Along with this increase, sports injuries are on the rise in the pediatric population.1 A major proportion of all injuries in children and adolescents are sports related.2–4 The National SAFE KIDS Campaign reported that 3.5 million children experience an injury by participating in recreational activities or sports every year.5 Of all sports-related injuries, chronic injuries and overuse represent up to 54% in youth sports.6,7 The group of young athletes between the ages of 10 and 14 appear to be especially prone to injury and overuse.8–10 Risk factors for sports injuries are commonly divided into intrinsic and extrinsic factors. Extrinsic factors such as training load, competition load, and equipment, and intrinsic factors like psychological factors, previous injury, or a previous history of physical conditioning are equally important in the context of youth sports injuries. However, because this article focuses on the growth dynamics of children and adolescents in the context of sports injuries, growth-related factors are discussed predominantly.
Issue Theme Sports Injuries and Imaging in Children; Guest Editor, Erich Sorantin, MD, PhD
Growth Dynamics in Childhood and Adolescence Growth and development occur at individual rates and are regulated genetically, hormonally, and by environmental and epigenetic factors.11,12 When evaluating growth progression, height and body mass increase markedly in the preadolescent and adolescent years. Girls reach their peak height velocity (PHV) at 12 years of age, boys at 14 years on average.13,14 Gains in total height are composed of increases in the length of different body parts growing at different speeds. Looking at changes in stature or total height, it is important to note that the maximum growth speed of the legs occurs before maximum increases in sitting height.15 Foot size reaches maximum growth velocity for girls and boys even 1.8 and 2.3 years before PHV, respectively.16 Adding to this complexity, the timing of PHV underlies secular trends and can vary considerably in collectives of healthy children.17,18 Skeletal growth dynamics are related to chronological age (CA), but an early
Copyright © 2014 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
DOI http://dx.doi.org/ 10.1055/s-0034-1389263. ISSN 1089-7860.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
Semin Musculoskelet Radiol 2014;18:465–468.
Growth Dynamics in Pediatric Sports Injuries
Zwick, Kocher
or late onset of pubertal growth spurt represents variations of the norm. It was the correlation of longitudinal height velocity data and secondary sex characteristics that led to the convenient definition that children 2 standard deviations above or below the average PHV should be referred to as early or late maturing, respectively.19 Using an age-dependent classification, girls reaching PHV at the age of 11 and boys at the age of 13 would be classified as early maturing. Girls and boys who attain PHV after 13 and 15 years of age, respectively, would be classified as late maturing.14 In various parts of the world, the growth spurts of children and adolescents seem to differ. Comparing published data from various sources, PHV is reported to vary regionally. Depending on the region, the time of maximum growth velocity occurs in girls between the ages of 10.8 and 12.2 and in boys between 13.3 and 14.4 years of age.20–23
Growth-Related Changes of the Skeletal System Bone mineral density (BMD) is lowest before the onset of PHV, and bone strength follows after increases in lean body mass during puberty.24,25 So one might argue that within a certain time window young people have to deal with relatively long lever arms and a low BMD. When long bones reach their fastest rate of growth before PHV and gains in lean body mass precede increases in bone strength, skeletal mechanics might therefore be set up for injury and overuse. Growth cartilage is less resistant to injury than mature bone.26 Because increases in lever-arm length occur while growth plate thickness is on the decline, torsional stresses at the growth plate are less well tolerated. Also, the length of the long bones increases before gains in length of the muscle-tendon complex.27,28 Muscular imbalances might therefore represent a temporal physiologic phenomenon because soft tissue tension and relative strength are factors that stimulate length gains in skeletal muscles.2,29 Joint cartilage stiffens during maturation at rates that currently are unknown in detail.30 Longer lever arms, an increasing lean body mass, and possible muscular imbalances might bear risks when the joint cartilage of junior athletes gets heavily loaded.
Age-Specific Risk Factors Intrinsic and extrinsic risk factors in youth sports change with age. Training volume and intensity commonly increases according to training age. Also, injury patterns could be attributed to age-specific changes in body composition. Normal changes in somatic growth could pose an intrinsic risk in adolescent sports. It is documented that sports injuries and overuse show distinct age-related patterns. 31 Avulsion fractures, Osgood-Schlatter disease, distal radius fractures, or osteochondral lesions are typical sports injuries of youth athletes showing age-related incidences ( ►Fig. 1). 32–37 However, there is still a lack of scientific evidence to clarify relations between specific ages and certain types of sports injuries. Seminars in Musculoskeletal Radiology
Vol. 18
No. 5/2014
Fig. 1 Growth velocity changes over time represent a typical wavelike shape. The pubertal growth spurt brings about several changes in body composition. Increases in lever-arm lengths of the legs and arms, a relatively low bone mineral density, and changes in strength and flexibility are intrinsic factors for youth sports injuries and overuse. Typical sports injuries of older children are displayed in relation to the pubertal growth sport.
Prevention The prevention of injuries is one of the main motivations for researchers in the field of pediatric sports medicine and sports science.38–43 Although some issues in prevention are sport specific, the vast majority of reports relate to physical fitness aspects. Age-appropriate training and conditioning of junior athletes is one of the biggest challenges for trainers, coaches, and administrators today.44–47 Most youth sports programs worldwide are currently aligned to CA. Although most young athletes are served well by this approach, earlyor late-maturing children and adolescents run the risk of getting overstrained or being underchallenged. It seems obvious that training and conditioning of children and adolescents should be individualized to meet their very individual needs during growth and maturation.
The Biological Age in Youth Sports Historically, the design of training programs for youth athletes was mainly aligned to CA. There is increased concern that this approach constitutes an extrinsic factor in pediatric sports injuries.48 Methods to estimate or determine the biological age of junior athletes are not commonly available today. Skeletal age (SA) determined by the interpretation of radiographs and developmental age (DA), obtained from anthropometric measurements and the assessment of sex characteristics, have not yet been implemented on a large scale in youth sports. Reasons for the limited implementation of SA and DA were described in a recent review by Lloyd et al.48 An approach to estimate the biological age of junior athletes by evaluating individual growth velocity dynamics bases on repeated measurements of stature is currently under investigation.49
Future Challenges in the Field of Youth Sports Injuries Understanding growth dynamics is a prerequisite when dealing with sports injuries in children and adolescents.
This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.
466
7
8
9
Fig. 2 The rate of change of biological age over time represents an interesting aspect of growth and development. A late-developing child is displayed to catch up with her chronological age. During a time period of 1.5 years, biological age catches up from being 2 years younger than the chronological age at the age of 8 to just 1.2 years younger at the age of 9.5. Catch-up phenomena are one of the reasons for repeated assessments of growth and development at short time intervals (unpublished data from reference49).
10
11 12
13
Because of the variability of growth spurt timing, the assessment and tracking of growth is required for each athlete. Any solution to estimate or determine the biological age of junior athletes should therefore be practicable in the youth sports setting. Any measurements required should be simple enough to enable families, coaches, or trainers to perform them regularly. Time intervals between assessments should be kept short to identify the onset of growth changes early. When comparing biological age and chronological age, differences vary over time. A late-maturing child might catch up with his or her CA in quite a short time (►Fig. 2). Training and conditioning of youth athletes should honor their individual biological age. This requires coaches and trainers to group children and adolescents according to their biological age rather than to their CA. Research on youth sports injuries should report findings in relation to the biological age or DA of the cohort studied. Most studies in the field still report on groups of children defined by their CA.
References 1 Gottschalk AW, Andrish JT. Epidemiology of sports injury in 2
3
4
5
6
pediatric athletes. Sports Med Arthrosc 2011;19(1):2–6 Hawkins D, Metheny J. Overuse injuries in youth sports: biomechanical considerations. Med Sci Sports Exerc 2001;33(10): 1701–1707 Valerio G, Gallè F, Mancusi C, et al. Pattern of fractures across pediatric age groups: analysis of individual and lifestyle factors. BMC Public Health 2010;10:656 Damore DT, Metzl JD, Ramundo M, Pan S, Van Amerongen R. Patterns in childhood sports injury. Pediatr Emerg Care 2003; 19(2):65–67 Safe Kids Worldwide. Coaching our kids to fewer injuries: a report on youth sports safety. Available at: http://www.safekids.org/ sites/default/files/documents/ResearchReports/Coaching%20Our %20Kids%20to%20Fewer%20Injuries%20A%20Report%20on% 20Youth%20Sports%20Safety%20-%20April%202012.pdf. Accessed on October 3, 2014 DiFiori JP, Benjamin HJ, Brenner JS, et al. Overuse injuries and burnout in youth sports: a position statement from the American
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