The Youth Athlete: A Practitioner’s Guide to Providing Comprehensive Sports Medicine Care

The Youth Athlete: A Practitioner’s Guide to Providing Comprehensive Sports Medicine Care includes topics that provide the most comprehensive and holistic understanding of the youth athlete. The foundation of the book focuses on the growth and development of the athlete from child to adolescence, balancing their physical, mental and emotional needs. The middle sections expand on this foundation, concentrating on common injuries and illnesses as well as unique topics (e.g., Female, Athlete Triad, Sports Specialization). Final sections emphasize specific sports (e.g., Soccer, Basketball, eSports), allowing the reader to synthesize the previous information to assist with return to play decision-making.

Written from a scientific perspective and incorporating evidence-based medicine into its content, this book is perfect for health care practitioners of varied specialties. The complete and comprehensive structure of the book will clearly distinguish it from all other textbooks on the market.

• Covers diverse topics that reflect our current understanding of youth athletes and issues related to their care
• Incorporates evidence-based approach, highlighting the latest state-of-the-art information and research
• Written by global content experts throughout the sports medicine field

• Language: English
• Publisher: Academic Press
• Release date: Jun 22, 2023
• ISBN: 9780323983198

Book preview

Preface

Physical activity through play and sports is a vital part of a child's growth and development. This is supported by research that has illustrated the short-term and long-term physical and emotional benefits of exercise. Physically active children will experience less obesity, diabetes, cardiovascular disease, and greater productivity over their lifetime. In addition, exercise and sports can assist with reducing anxiety and depression, especially during the pivotal time of puberty. Finally, physically active children develop into physically active adults who promote activity in their own children.

Unfortunately, a variety of factors can impede a child's ability to participate in exercise and sport. The Aspen Sports Institute notes that most children will quit sports by the age of 11 years. Youth athletes will note that training and competing in sport is no longer fun. Factors contributing to the cessation of exercise and sport include injury, illness, burnout, early specialization, technology (e.g. Video games, time spent on phones), peer, parent or coach pressure, and socioeconomic disparities impacting access to sports. In an age of social media and lucrative contracts, youth sports have become too competitive as parents and the youth sports industrial complex attempt to emulate professional athletes in hopes of riches. Such continuous training and pressure can potentially lead to an increase in injuries and loss of perspective on the benefits of exercise.

Thus, it is from a mindful perspective of advocating for a better understanding of the youth athlete that we developed The Youth Athlete: A Practitioner's Guide to Providing Comprehensive Sports Medicine Care. Our book provides the most comprehensive and holistic understanding of the youth athlete. Diverse experts in the field of Sports Medicine address the whole spectrum of the youth athlete. Our content experts incorporate evidence-based information to help the reader understand the physical and emotional aspects of the youth athlete while balancing the benefits and risk of play, exercise and sport.

The wealth of information in The Youth Athlete is centered around the athlete. The foundation of the book starts with a focus on the growth and development of the athlete from child to adolescence balancing their physical, mental, and emotional needs. We expand on this foundation, venturing into common injuries and illnesses as well as unique topics (e.g., Athletes with Disabilities, Female Athlete Triad, Substance Abuse, Sports Specialization, etc.). The final section focuses on specific sports (e.g., Basketball, eSports, Soccer, Swimming) allowing the reader to synthesize the previous information to assist with managing injuries and return to play decision making.

We sincerely hope this book will become the comprehensive resource used by sports medicine practitioners at all levels. We wish to thank all our contributing authors for their time and effort. Now get out there and play!

Brian J. Krabak, MD MBA

Alison Brooks, MD MPH

Section I

Foundations

Outline

Part I. Growth and development

Chapter 1. Physical maturation

Chapter 2. Mental development

Chapter 3. Hormonal changes

Chapter 4. Physical activity and exercise science

Chapter 5. Gender in sport

Part II. Sports participation

Chapter 6. Benefits of youth sports

Chapter 7. Strength and power training

Chapter 8. Preparticipation physical examination

Chapter 9. Social determinants of health and youth sports

Chapter 10. Sports advocacy and equity in sports

Part I

Growth and development

Outline

Chapter 1. Physical maturation

Chapter 2. Mental development

Chapter 3. Hormonal changes

Chapter 4. Physical activity and exercise science

Chapter 5. Gender in sport

Chapter 1: Physical maturation

Mariah Sisson ¹ , Brian S. Harvey ² , and Natalie C. Stork ²       ¹ Department of Pediatrics, CentraCare, St. Cloud, MN, United States      ² Orthopedic Surgery, University of Missouri-Kansas City School of Medicine, Children's Mercy Hospital, Kansas City, MO, United States

Abstract

The physical maturation of a young athlete is multifaceted encompassing changes related to bone, muscle, body composition, and neuromuscular control. This process is commonly influenced by gender, age, genetics, and external factors. Physical maturation has a unique effect on the acquisition of skills and risk of injury in the young developing athlete. Developing an understanding of the changes that occur physically in the developing athlete can help identify when and how to train, aid in recognizing risk, and identify preventative measures to optimize the health and well-being of youth athletes.

Keywords

Body composition; Bone and muscle development; Neuromuscular control; Peak height velocity; Physical maturation; Young athlete

Physical maturation throughout childhood and adolescence is a multifactorial process that has many implications on athletic capabilities, injury risk, and long-term health. An overall biopsychosocial process occurs in three distinct identities of growth, maturation, and development leading to physical changes in bone, muscle, and body composition. ¹ The developmental and physical maturation process have a distinct effect on skill acquisition in sport and injury risk in the young athlete. This process is unique to each specific individual athlete, depending on gender, genetics, and external factors.

In addition, throughout the maturation process, changes occur throughout the musculoskeletal system which leads to an increased risk of specific injuries. Asynchronous growth between bone and muscle puts a unique stress on the developing athlete leading to an increased risk of injury at the weak point, the physis, in the growing athlete. Additionally, during adolescence, there is a notable decrease in age-adjusted bone mineral density just prior to peak height velocity (PHV). ² Injuries during this crucial time can have a significant effect on athletic development and hinder future participation and potential. Outside of injury risk, the timing of these changes can give young athletes inherent advantages and disadvantages as a competitor. ³

Bone maturation

Adolescence is a prime period for changes to the skeletal system which has long-term implications on the adult bone structure. It is well known that peak bone mass acquisition occurs during adolescence and is a crucial factor for bone mass and fracture risk in adulthood. ⁴ The process of bone changes through adolescence requires delicate communication between osteoblasts and osteoclasts to remodel existing bone and model the newly formed bone. Linear growth occurs first, followed by changes in bone width. These changes occur before mineralization by approximately 8 months, during which time there is thought to be an increased risk of injury. ⁵

Lifetime bone health has factors that are both nonmodifiable and modifiable, many of which are important to consider and evaluate during youth. Genetic factors are the primary nonmodifiable determinant of bone health and include variations among males and females, as well as racial differences among populations. Modifiable factors for lifetime bone health include physical activity and nutrition. Both factors should be considered when caring for an adolescent athlete; too much or not enough can positively or negatively affect overall bone mass acquisition. For example, mechanical stress on the skeletal system through high-impact and weight-bearing activities such as walking, jogging, and skipping can positively increase bone formation. However, too much of these activities can lead to an increase in fracture risk, secondary to the same mechanical stress that is put on the bone.

From a nutrition standpoint, the intake of a well-balanced diet is important. This includes intake of highly utilized vitamins and minerals, such as calcium and vitamin D, as well as, consuming the appropriate caloric intake to maintain fuel for the changes occurring in the musculoskeletal system. Assessing athletes regarding their nutritional intake is something important for primary care and sports practitioners to monitor as it has both short-term and long-term complications that can hinder an athlete's ability and career.

The importance of dietary vitamins and minerals is apparent when understanding the mineralization process of bony maturation. Mineralization occurs in the bony matrix with the deposition of calcium and phosphate. Over 99% of total body calcium is found within the skeletal system. Vitamin D is utilized during this time to aid in the absorption of dietary calcium. ⁶ It is the combination of increased bone mass, as discussed above, and maximum strengthening, which will be discussed later, that leads to peak bone mass. Approximately half of peak bone mass is thought to be acquired during adolescence with the remainder achieved by age 30 (Fig. 1.1). ⁷ Therefore, emphasis should be placed on nutritional intake during adolescence. As children are evaluated at their well-child check or presenting with injuries such as fractures, the nutritional status and daily intake of calcium and vitamin D should be assessed to ensure bone health is optimized both acutely and for leading into adulthood.

As briefly addressed above, changes to the skeletal structure during adolescence put this developing population at an increased risk of unique injuries not seen in the much younger or adult population. The presence of growth plates, and the changes in bone composition secondary to growth and mineralization, are two primary differences in youth which affect their risk for injury. Growth plates are highly active at various times in childhood. The process of proliferation and eventual closure of the growth plate is multifactorial, utilizing features at the cellular level and the hormonal level. ⁷ During the time of increased growth, the growth plate becomes more fragile than the surrounding tendons and ligaments inherently increasing the risk of skeletal injury at these locations. ² Additionally, as bone is modeled and remodeled, PHV precedes the bone mineralization process, as noted earlier, which can lead to increased risk of fracture secondary to the differences in timing of bone growth to mineralization (Fig. 1.2). ² The Salter-Harris classification system is commonly used to characterize fractures as they pertain to the growth plate. ¹⁰ In addition to growth plate fractures, growth centers, apophyses, are a common location for overuse injuries, such as the case with Osgood Schlatter or Severs disease among many others. Overall, during this time, the physes and apophyses undergoing rapid growth are less resistant to tensile and shear forces. There are many hypotheses to evaluate further causes leading which contribute to these findings including increased joint hypermobility, anatomic malalignment, utilization of proper fitting equipment, and generalized overscheduling of young athletes subsequently increasing their workload. ²

Figure 1.1  Illustration of bone mass acquisition to reach peak bone mass in both men and women. ⁸

Figure 1.2  Illustration to evaluate changes in bone mineral content during adolescence in girls and boys. ⁹

Neural changes in maturation

With the changes occurring throughout the musculoskeletal system with growth and maturation, underlying neural control and changes should not be overlooked. Having appropriate neuromuscular control is dependent on the interaction between the neural and muscular system. ¹¹ Coordination of movement and sport-specific activity requires utilization of both fine motor skills as well as gross motor function. The corticospinal tract, which functions primarily to improve fine motor skills, and the extrapyramidal tracts, which are more involved with the gross motor pathways of coordinated movement and utilization of the appropriate musculature. ¹² When evaluating fine motor functional increases, there has been evidence to support that the contraction time of intrinsic hand muscles, important for fine motor skills, decreased during the transition from childhood to adulthood. ¹³ It is during adolescence, that ongoing maturation is occurring in the corticospinal tract leading to increased organization and myelination. This in turn leads to proposed neural plasticity during this time which can be influenced by practice of preferred activities and muscular activation. ¹³ The acquisition of gross motor skills can be evaluated when further reviewing gait and postural control. Gait function under the age of two is wide-based with hyperflexion of the hips and knees with maturation into an adult-like gait pattern around the age of 7 years old. However, further development in gait function continues to mature during adolescence to further define cadence, step length, and base of support. ¹²

Additionally, during childhood, the regulation of movement is considered reactive and transitions to a more proactive control as children get older. ¹¹ To further evaluate how this relates to and develops in the adolescent athlete, neural changes can be followed as it relates to the stretch-shortening cycle of muscle action. Some of the age-related changes in the neural system that influence stretch-shortening cycle include greater preactivation, increased stretch reflex magnitude, and musculotendinous stiffness. ¹¹

Muscle maturation

Muscular changes throughout childhood and adolescence include not only growth but changes in overall function and control. During maturation, muscle undergoes growth in length and muscular cross-sectional diameter. Additional changes include the execution of motor function, coordination, and neuromuscular control which influence strength, speed, flexibility, and power. Of note, significant improvement in speed and flexibility are often seen prior to an athlete reaching their PHV whereas improvement in strength and power often occur after PHV. ¹⁴

Prior to an adolescent reaching PHV, the changes in their physical strength are thought to be driven by improving neuromuscular activation. ¹⁵ During this phase, both males and females can see similar strength gains up until about age 14. ¹⁵ Further changes related to muscle strength are then influenced by the increase in androgen levels, particularly testosterone, during adolescence. Based on increasing testosterone levels, males see an increase in the rate of strength gains compared to females, which tend to plateau. ¹⁶

Flexibility can show increases and decreases related to both intrinsic and extrinsic factors of an athlete. Females tend to have increased flexibility compared to males in early adolescence; with females reaching peak flexibility near 14 years of age while males show declining flexibility starting as early as 7 years of age. ¹⁷ Notable intrinsic factors that influence flexibility include the growth of the bone and muscles as well as individual alignment and joint laxity. The asynchronous growth between adolescent bone and muscle might help explain the overall decrease in flexibility during maturity. Extrinsic factors affecting flexibility include the type of physical activity, training (e.g., warm-up/cool down), prior injury, and the environment (e.g., temperature). ¹⁶

The product of improved strength and speed, leads to increases in power. ¹⁸ Advances in power can be seen during early, middle, and late adolescence as speed and strength increase at various times. Given the many factors that play into increased power, there is difficulty in determining the ideal time to optimize the training focus on overall power. ¹⁹

Changes in speed during maturation are mainly due to neural changes leading to improved neuromuscular control. ¹⁸ Speed development is a basic principle for athletic development that provides a framework for increased abilities and functional endeavors. During adolescence, engagement in activities that enhance neuromuscular control is important for enhancing the speed and athletic abilities should not be overlooked during this time. Speed work can be incorporated into a training regimen far beyond sprint work and take on the appearance of agility work or plyometrics. ¹⁸ Plyometrics targets the neuromuscular system to react more quickly to the stretch-shortening cycle leading to increased movement speed. ²⁰

Body composition

As the changes in bone and muscle occur during the physical maturation process, so does the body composition of adolescents. These changes to body composition can be an important determinant of athletic performance and will vary depending on age, sex, and stage of development. ³ Body composition is often simplified into two main categories, fat mass (FM), and free fat mass (FFM). ¹⁶ However, body composition can be dissected further to include total body water, fat-free dry mass, and bone mineral density, all of which can have meaningful effects on changes in body composition. ³ Fat-free mass tends to follow a growth pattern like height and weight; therefore, the adolescent growth spurt is a time of many changes not merely reflected in height. Fat mass, however, is influenced by not only growth and maturation, but also diet and training patterns ³ and is more variable relative to FFM. Differences in FFM are negligible among males and females during the childhood years prior to puberty, becoming much more evident in the adolescent years. ³ During puberty, males experience increased gains in lean muscle mass compared to their gains in fat mass, whereas females experience increased gains in fat mass. The increase in free fat mass in males is about 1.5 times greater during the transition from adolescence to adulthood when compared to the changes in free fat mass among females. This difference is a direct reflection of the increase in muscle mass that occurs in males relative to females. In contrast, females experience similar increased gains in fat mass compared to males during the same time frame. ³

Although multifaceted, the endpoint of the maturation process, related to body composition, can set apart males and females in sport readiness. ¹ Particularly, early maturation in males lends to the increased height, weight, free fat mass, strength, and power at a younger chronologic age than average maturing males. These changes can be a competitive advantage to the early maturing male in many sports. ³ The opposite can be true for female athletes whose sports might require a lean body type, with later maturing females during adolescence having shorter stature and less weight during that prime period of adolescent athletic achievements. The variations throughout adolescence can lead to players trying to change their body composition in both healthy, increasing muscle mass with resistance training, and unhealthy ways, cutting weight or trying to maintain a lean appearance for certain sports such as running, gymnastics, cheer, and/or dance. Additionally, those individuals who are late maturing will often grow for a longer period than their early maturing counterparts and surpass those individuals in overall height. ³

To further break down the changes that are affecting body composition requires looking at the more individualized changes seen with height and weight. PHV is particularly important when evaluating overall changes in body composition during adolescence. PHV is often used as a marker of biological maturation; however, this can vary significantly among athletes of the same chronological age. ¹⁸ The pubertal growth spurt is noted to begin during early adolescence in both males and females. The peak of growth often leads to height increases of up to 3–4 inches per year. The average timing of this varies among males and females with males peaking around 13–14 years of age and females peaking around 11–12 years of age (Fig. 1.3). Changes in body mass occur shortly after the changes related to increased height. ¹ Body mass index (BMI) is a calculation obtained by taking weight in kilograms and dividing it by height in meters squared. Given that weight is influenced by multiple characteristics, increased fat mass can influence elevations in BMI as can increased muscle mass. This is noted to be particularly troublesome in the young athlete population who are actively working to achieve increased free fat mass through training regimens, and without further evaluation of body composition could be labeled as overweight or obese, when their free fat mass is what has proportionally increased their BMI. ²² BMI should be considered as a screening tool to evaluate suspected body composition but should be used with caution in athletes and individuals who do have a more muscular body type. ²³

Physical maturation and sport readiness

The following content discusses a variety of different sport-specific considerations to utilize when an athlete is advancing their training and skills. Some sports rely more heavily on specifics related directly to the maturing athlete and the capabilities that come with growth and maturation while others have an approach more focused on injury prevention as it relates to sports injuries in the growing athlete. As noted previously in this chapter, the many changes related to maturing athlete can help them advance in their sports but also puts them at a unique injury risk that should not be overlooked. These considerations are not without exceptions and are based on expert opinion.

Resistance training

Resistance training has been shown to be safe and effective in youth athletes optimizing athletic potential with intricate relations to the changes in physical maturation as noted earlier in the chapter. Ultimately, utilization of resistance training should progress according to age, motor skill competency, technical proficiency, and existing strength. ²⁴ During the pre-PHV, emphasis should be placed on foundational movements and the technical development of body weight and weightlifting skills while working on general strength. ¹⁵ This then transitions to strength development and increasing training intensity, increasing load as function allows. ²⁴ The final step in optimizing resistance training in the long-term development of sport-specific training programs that may include high-intensity resistance exercises. ¹⁵

Figure 1.3  Illustration of height velocities in both males and females including visualization of peak height velocity. ²¹

Tackling in football

As with other sport-specific topics, there is little data to influence youth football participation, but what is known and recommended at this time, focuses on minimizing injury risk, particularly associated with tackling. The risk of catastrophic injury during participation is lower for the younger athletes than compared to older athletes; however, tackling is a common culprit for injury. Injury mitigation strategies that have been evaluated include limiting full-contact practice and delaying introduction to tackling; although data are not sound at this time to support these strategies. Current recommendations for youth football put forth in a policy statement by the American Academy of Pediatrics Council on Youth Sports Medicine and Fitness include the enforcement of rules to minimize improper and illegal contact, evaluating ways to decrease number of impacts to the head during participation in football, optimizing neuromuscular control and tackling technique, strengthening of the musculature of the neck. ²⁵ Importantly, research has been ongoing to further quantify the risk of injury based on age, weight, size, and maturity. However, there are limited data available to truly identify the risk, but the current correlations show an increased risk of injury based on age and grade level with heavier players also being at increased risk. ²⁶

Heading in soccer

Heading in soccer is a topic that takes into consideration potential risk with limited data to support or refute the concern that repetitive heading can lead to subconcussive impacts and concussive-like effects. ²⁷ When evaluating heading in soccer, it is important to consider many factors related to the risk of head injury including age, neck strength, body control, and the many differences among males and females. Male soccer players are noted to head more than females, but females are more likely to experience a head injury. ²⁸ As previously described age, neuromuscular control, strength, and gender all play a role when deciding if a young athlete is ready to start heading the ball in soccer. Frequency of purposeful heading increases with age. ²⁷ Due to the concerns with heading during competition and practice, the U. S. Soccer Federation eliminated heading in players <10 and put limitations on 11–13-year-old players allowing only 15–20 headers in practice per week. ²⁸

Body checking in hockey

Like heading changes in soccer, age-based guidelines have been developed recently in hockey regarding body checking due to the injury risk. Research looking at developmental causes for the decreased injury risk when increasing the age for body checking is lacking. Body checking is known to be a significant risk factor for injury in hockey players, increasing risk of injury up to threefold in the 11–12-year-old age range. This led U. S. hockey to increase the age at which body checking was allowed starting with 13–14-year-old athletes in 2011 and Canada hockey closely followed suit with a similar rule change. ²⁹ The American Academy of Pediatrics recommends restricting body checking until at least age 15. ³⁰ Additionally, the U. S. National Federation of State High School Associations implemented changes regarding decreasing risk of injury in hockey players by enforcing more strict penalties. Rules related to dangerous checking and boarding from behind now lead to a major penalty. There is sparse evidence to support increased rules and regulations that have had positive effects on the safety of players. However, there is some evidence to support increased rules and regulations around body checking, specifically at younger ages, and decreased injury. ³¹ With this knowledge around checking, it should also be known that the risk of injury is considered to increase as players become bigger, faster, and stronger during which time they also begin to wear less protective equipment. ³²

Pointe in ballet

Dancing en pointe is often an aspiration of young dancers who participate in ballet. However, the ability to appropriately advance to pointe is a multifactorial process requiring maturity, strength, flexibility, and appropriate ballet training leading up to this advancement. ³³ As with many other advancements in sports activities, there is little evidence or standardization to support when the appropriate time is to dance en pointe. Moving toward dancing en pointe is a gradual process for which dance studios have set age restrictions or meet individually with dancers to determine readiness. With years of training in ballet, many dancers can achieve the necessary skills for pointe between 11and 13. Although not every dancer will achieve skills for pointe during this period and some never attain the necessary skills. Waiting for growth plate closure is not deemed necessary as a qualifier for pointe as there is minimal risk for long-term inadequate growth based solely on dancing pointe. ³³ Foot shape, regarding the angle of the toes, does not matter when going en pointe. However, variations in foot type should be considered if the athlete experiences foot pain, bony abnormalities, and adjustments to pointe shoes. Flexibility is a key factor to achieve pointe and minimize risk of injury including the ability to have at least 90 degrees of plantar flexion at the foot and ankle. ³³ Technique and alignment should be evaluated with appropriate engagement head to toe to ensure ability to dance in this manner. Dancers making this advancement should also have appropriate strength to hold positions. Overall, the mental maturity of an individual should be so that with appropriate constructive feedback an individual can learn corrective techniques and apply them. ³³

Distance running

Long-distance running is another activity that with special considerations can be achieved with optimal success in the youth population. It is of utmost importance to ensure when an athlete is training for long-distance running that growth remains normal and good nutritional intake continues. The guidelines that are considered when establishing appropriate training and distances are purely opinion based with limited evidence to support these guides. A consensus statement published in 2021 helped to further define and address injury prevention, risk factors for injury, and long-term effects of distance running. With currently available research on youth distance running, the consensus statement believes that if appropriate training programs are followed then youth can appropriately run long-distance races. ³⁴

Summary

Knowing the changes related to bone, neural, muscle, and body composition (Table 1.1) that occur throughout the physical maturation process, with many factors contributing to a broad spectrum of variation, can further help to tailor an athlete's training to optimize their function during each phase of growth and development while also aiming to decrease the risk of injury. ¹⁸ Knowing the injury risk associated with bone growth as well as importance of optimizing adolescent nutrition for bone health can be pertinent components of the athlete sport participation and long-term health. Changes in muscle from a physical and functional standpoint can be utilized to further enhance their abilities. However, these modalities of training should not focus entirely on one region of neuromuscular control and eliminate other fundamentals entirely as each is a building block for the other. For instance, if an athlete has attained high aerobic fitness but has low strength, they are at an increase for overuse injuries. ¹⁸ Supporting an athlete through changes in body composition and utilizing these changes for specific sports and training should also be of importance to all who care, coach, and work with youth athletes. The physical changes throughout adolescence can subsequently affect sport selection, participation, and psychosocial development. ³

Table 1.1

Key points

• Physical maturation is a multifaceted process characterized by changes in bone, muscle, body composition, and neuromuscular control

• Gender, age, genetics, and external factors all play a vital role in this complex process

• A comprehensive understanding of physical maturation can help identify and counsel athletes on recognizing risk of injury, identifying preventive measures to optimize the health and well-being, and aiding in conversations around training.

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Chapter 2: Mental development

David O. Conant-Norville     Mind Matters PC, Hillsboro, OR, United States

Abstract

The young athlete experiences complex mental developmental changes through childhood and adolescence. Knowing these developmental processes and stages will help the sports practitioner to understand the athletes’ cognitive, emotional, and behavioral functioning based on the athletes’ ages and maturity levels. This chapter briefly describes the functioning of the mind as the individual grows from infancy to adulthood. The evolutionary triune brain model and mental system model are presented as two different models for understanding the integration of mental functioning as the child grows and develops. An age and stage model designed for the sports practitioner is presented using Piaget's stages of cognitive development, Erickson's model of psychosocial development, and more recent findings of brain neuroscience. The five stages of development described include attachment, play, skills, competition, and commitment.

Keywords

Athlete mental development; Athletic mind; Attachment; Commitment; Competition; Mental integration; Play; Skills; Youth athlete; Youth sports

Mental development: the emotional and cognitive changes from childhood through adolescence

To fully understand the young athlete, the clinical practitioner must learn basic principles of human mental development. While there is still much to discover from this complex scientific inquiry, many important principles of mental growth and development can help the sports medicine clinician understand the complex thoughts and emotions of young athletes throughout their developmental journey. The goal of this chapter is to present a structured view of mental development and describe how evolving mental capacities impact an athlete's sports experience and performance.

Defining the mind

When discussing mental development, we are essentially describing the evolution of the human mind. But what is the mind? This has been an elusive question often avoided by medical professionals. One of the most useful definitions is by Dan Siegel MD, a prolific author and psychiatrist. He defines the mind as an embodied and relational process that regulates the flow of energy and information. ¹ While this seems a simple phrase, it is a very complex concept. To be clear, the mind is described as a process, not a structure. The mind is embodied in the brain and nervous system, and even in the relationships between individuals. The mind is the process of what occurs in the brain and all its somatic connections. It is the software not the computer. Like a computer and the operating software, the brain and the mind are not separate, but integrated, and both are essential for mental functioning. Another point to emphasize is that this process regulates the flow of energy and information. Flow denotes constant movement and change. Energy describes all energy sources from electromagnet energy such as light and heat, to vibrational and physical energy such as sound and touch, to chemical energy such as taste and smell. The information comes in patterned forms interpreted as symbolic. The mind is the process of accepting information from multiple sources, processing the input, interpreting the information, and directing a response. At birth, the neonate's brain is ready to take on the world outside of the womb with all the sensory input from internal (body) and external (the world) sources. While relatively primitive in functioning, unlike most other animals, the infant's mind is actively growing and adapting to regulate the flow of energy and information for survival and growth. While the initial development of brain structure is primarily genetically determined, as the person ages and gains more experiences with the surroundings, environmental influences take on a greater role in shaping the growth of the mind. The growth of the brain and the mind is determined by both genetics and environmental experiences. The older the individual, the greater the environmental influences on mental health. Mental health is the mind's ability to observe, process, and adaptively respond to environmental influences and should be distinguished from dysfunction, which we refer to as mental illness. This is not a discussion of disorders of the mind or treatment strategies, but a review of normal and healthy developmental trends.

Integrating body functioning, behavior, emotion, cognition, and relationships

Mental input is first driven by sensory systems that detect energy. Mental output is divided into several components that can be useful for greater understanding. These components are body functioning and homeostasis, behavior (motor activity), emotion (feelings), cognition (thinking), and interpersonal relationships. Mental processing is the stage between the intake of information and the output of the action. Mental development involves the growth of the brain with the evolution of nerve cell maturity and increasing neuron connectivity into complex cell networks that can interpret sensory signals as patterns of discreet information packets. As these packets of information are present in the mind, brain growth is further stimulated, and networks become more complex. This allows learning to occur. Ultimately, the evolution of the mind is to allow the individual to survive and understand the conditions in which the individual lives, identifying the patterns of information to predict the future, assess choices, and act. ² As highly social animals, humans must learn the social context and communication skills to successfully build relationships in their communities. As the human mind develops, it is more able to regulate body functioning and behavior, as well as emotion, thinking, or relationships with others. Body functioning is necessary as a homeostatic foundation for growth and development. Behavior is our means of adapting to our surrounding, often by moving our muscles. Emotion serves to denote meaning such as danger, reward, salience, and motivation. Emotion drives choices. Cognition is the process of analyzing information, comparing it to previously retained memories, considering multiple options, and making complex and conscious choices to adapt to the environment. Developing and maintaining interpersonal relationships is essential for social animals, such as humans, to live and function together in complex groups. The integration of all these components is required for the mind to work effectively, and it is the growing integration of the many elements of the mind that is critical for a functioning person.

Brain development and its effect on the mind

Neuroplasticity, or the ability of the brain to adapt, change, build connections, and transfer function to different neural networks, continues throughout the lifespan of the individual. However, early growth and development of the mind during childhood and adolescence create the foundations of mental health for the individual's lifetime.

Brain development begins during the first trimester of gestation, but more dramatic development occurs during the second trimester as neuronal cells migrate together and begin to create the early structure of the central nervous system. Toxic exposure during this trimester, such as heavy ethanol use by the mother, can profoundly impair early brain development at this critical stage and have lifelong consequences. New research also shows that brain development in utero, particularly in the third trimester, is also influenced by sensory information received by the fetus while still in the womb. ³

At birth, the neonate's brain cells are immature but plentiful. This process of neural growth and cell network formation continues at an accelerated pace as the infant senses the outside world and organizes basic somatic functioning. Respiratory, cardiac, gastrointestinal, motor, and sensory functioning are all coming online and are stimulated by the flood of energy and information presented to the evolving mind. Brain growth and development are stimulated by increased brain cell activity. Neurons (brain cells) are connecting and growing axonal projections to connect to other neurons and form cell networks in the brain. A common axiom is "cells that fire together wire together." ⁴ Environmental energy stimulates sensory cells, which then signals cell networks to process it into meaningful patterns of information. For example, a neonate uses vision for the first time out of the womb, experiencing light energy. Light might come in various wavelengths (colors) and patterns (a mother's face). Repetitive exposure to this patterned light when associated with warmth and smell, and taste of breast milk with a full belly might signal to the infant that these experiences are associated with each other. In this way, energy becomes sensory input and is processed into information, creating a mental model that can help the infant understand the world and direct behavior (crying when hungry and calmness when the belly is full). When information is presented in a repetitive and predictable pattern, brain growth and organization are stimulated, and learning will occur. Over time the mind evolves to become a prediction process that uses patterns of information to drive both conscious and unconscious actions.

Mental development proceeds with predictable and orderly timing that is genetically determined and experientially directed. While genetic programming may determine the timing of critical brain growth phases, it is experientially driven mental growth that enables an individual's ability to adapt within the environment. While little can be done at this time to alter genetic directives of growth, the environmental experiences of the child and adolescent, which are the foundation of learning about the self in the world and social group, can be altered and enriched. Many models have been developed to describe mental development and function. Two different and useful models are included to aid the understanding of mental activity and growth.

The triune brain

Genetically determined growth of brain fiber tracts generally proceeds from bottom to top and from back to front. ⁵ The classic description of the brain is the triune brain model described in the 1960s by neuroscientist Paul MacLean. ⁶ He conceptualized the brain by using an evolutionary perspective from the most primitive structures common in many animals to the most advanced structures that are unique to humans (and other primates). He metaphorically described the human brain with three layers (see Fig. 2.1).

Figure 2.1  The 3 layers of the Triune Brain are structured with the base structure of brain stem and cerebellum. The second structure is the mid-brain and limbic system. The final layer is the cortex.

Layer O ne is the most primitive layer. It includes the brainstem and lower brain structures that are responsible for automatic body regulatory functioning (body temperature, blood glucose level, alertness, reflex movements, etc.). This layer is common to both humans and lizards, is commonly referred to as the lizard brain, and can produce sensations and actions such as hunger, sleep, heart rate, respiration, and thermoregulation. With injury or threat, it can initiate a stress response through a different system. This system is primarily instinctual and genetically driven.

Layer T wo is a more recently evolved region that manages emotions. These structures and associated functions are thought to be more related to mammals and are commonly called the mammalian brain. Emotion is the primary function of this layer. Emotion gives meaning to experiences and drives behavior. Reactions are more open to environmental and social influence. These functions allow mammals to care for the young and develop social groups. Emotion experienced in Layer Two can connect to Layer One. For example, fear can lead to shivering or sweating, and sadness can lead to changes in appetite or sleep.

Layer T hree is the most recently evolved of the brain regions and involves the cortex or outer layers of the brain more committed to adaptive learning, including cognition, memory storage, sensory processing, abstraction, and reflection. This layer is sometimes referred to as the primate brain, with the human component as the most highly developed cortex or outer layer and specifically the prefrontal cortex responsible for conscious and contemplative thought. This area is responsible for allowing humans to adapt to many cultures and environments, plan elaborate structures, and consider complex ideas. This is the layer responsible for language and complex tool use. Layer Three sends information to Layer Two and Layer One and increases the ability of the mind to regulate the flow of energy and information. The triune brain hypothesis is an evolutionary and anatomic effort to explain the integration that occurs with mental development and presents useful concepts to help us understand ourselves. As humans mature, Layer One is stabilized initially, then Layer Two matures and integrates, followed by the delayed and slowly developing complex cerebral cortex, leading to the increasing influence of Layer Three through childhood and adolescence and into adulthood.

The system model

The system model described by psychologist Daniel Kahneman is another way to conceptualize mental development and functioning. ⁷ This model uses the concept of heuristics (or patterns of information and action) to explain how the mind adapts and reacts when exposed to experiential information (see Fig. 2.2).

System One is the rapid response system that takes in symbolic information and responds with definitive action. System Two is the slow response system that allows for deliberate and complex thought with consideration of multiple choices and more nuanced action.

System One is the common response system that accounts for our habits, biases, and efficient functioning. It is driven by heuristic patterns that direct actions to common sensory inputs or very uncommon inputs and directs quick and predictable responses. It takes in information, sorts it rapidly, then acts unconsciously. This system tends to jump to conclusions. System One is in play when the sensory input is routine and routine responses are needed. These rapidly directed actions require relatively little energy utilization by the brain and are usually appropriate. System One also responds when there is a very unusual or very unpredictable sensory input that could signal a potentially dangerous threat to the individual. In this case, a fast and decisive action must be taken to protect the individual.

Figure 2.2  The system model of mental functioning separates mental activity by systems. System One is the primary system for routine decision-making while System Two is called on for more complex analysis and decisions. The System One heuristics are essential for everyday decisions that are quick and unconscious while the more time and energy demanding analytic and conscious approach of System Two is back up for more challenging problems and new complex learning.

System Two is the deliberative and conscious system and is much more energy-demanding than System One. Unlike System One, it does not take shortcuts and works to gather a full data set before considering an action. System Two comes online when the mind is in problem-solving mode. It does not work under stress or threat, or in a routine situation. When overwhelmed, it defers action to System One. System Two, which more actively engages prefrontal cortex structures, develops later than System One because it relies on memory from experiential learning with input from the prefrontal cortex, which is the last brain structure to develop to full maturity. System Two is engaged in active new learning during childhood but adapts to perform more analytical functioning and complex decision-making during adolescence and into adulthood.

This system model tries to describe mental functioning and emphasizes system adaptation depending on the type of challenge being presented to the mind. It also emphasizes the importance of mental process integration throughout the brain and between the two systems for optimal mental growth and health, reinforcing the idea that both genetic and environmental influences work simultaneously to build healthy mental functioning.

The mental stages of the youth athlete

Human development has been commonly described using developmental stages. While mental development is continual throughout life, the strategy of describing specific stages of development can be helpful as a shorthand strategy for understanding the developmental process. The reader should be aware that these age-related stages are only approximations of general trends of mental growth and that mental functioning can be affected by many different environmental stressors or supports that can affect developmental progress.

The developmental stages that will be highlighted in this chapter are infancy, early childhood, later childhood, puberty and early adolescence, and later adolescence with transition to adulthood. Each of these stages presents both risk and opportunity for mental growth or impairment. Successful mental development requires social support and environmental enrichment during each of these growth phases and creates tremendous opportunities for learning. For the sports medicine practitioner working with the youth athlete, the transitions from childhood to adolescence and from adolescence to adulthood are most relevant but understanding the early life of the athlete can help explain the mental functioning patterns observed in older athletes.

To connect mental development to the experience of the youth athlete, this chapter presents a scheme naming the major sport related (and human) mental challenge during each period (see Fig. 2.3). The stages are attachment, play, skills, competition, and commitment. These stages align with classic stages of intellectual development described by Jean Piaget ⁸ and psychosocial stages of development proposed by Erik Erickson. ⁹ Each stage will be described from a biological, psychological, and social perspective, focusing on the importance of mental integration of developmental changes.

Attachment (0–3 years)

One of the first challenges of the evolving mind is the process of attachment. While the mind is learning to regulate the flow of information within the body (such as thermoregulation, breathing, feeding, sleep), it is important for the vulnerable infant human to connect to caregivers. This attachment stage is basic and therefore important for all sports practitioners to understand, since the type of early attachment may help to explain a young athlete's social connections to family, coaches, and teammates later in their life. Research has differentiated early attachment models as either secure and insecure. ⁵ While the "secure attachment model is the predominant form, insecure attachment models" are described in several forms. ⁴ The type of attachment model is important to consider when emotions, behaviors, and interpersonal relationships are difficult to explain and might require a referral for further assessment. Care should be taken to avoid blame if there is an attachment dysfunction, as causes are complicated and not always easily explained or understood.

The infant is very dependent on caregivers for survival. The care providers' intunement to the needs of the infant is essential for the infant to develop an internal model of trust that the world is predictable and consistent. If the infant experiences the world, through the actions of caregivers, as safe, responsive, and soothing during times of discomfort or distress, then the infant is likely to develop what is referred to as a secure attachment. About two-thirds of the population have developed a secure attachment model during infancy to help them feel safe, secure, and trusting. ⁴ This secure attachment enables the young child to learn strategies to sooth emotional distress. The attachment relationship model that the child develops early in life has a great influence on forming future relationships. Children who have learned to interpret the world as a relatively safe place tend to be more trusting and socially engaging. In an attachment research protocol, the Strange Situation Test, where a toddler is separated from their caregiver briefly and then reunited, the securely attached child will quickly move toward the caregiver, usually a parent, with happiness to make contact and sooth emotions. When adequately reassured and calm the securely attached child will leave the parent and move away to explore the toys in the room. This internalized social model is repeatedly recreated as children age and grow and is often seen in sports-related experiences during times of stress and uncertainty. The youth athlete with a secure attachment is likely to respond positively to trusted authority figures who provide a safe and soothing experience by calming their emotional distress, adapting to the new situation, and focusing on performance with less anxiety.

Figure 2.3  The mental development of youth athletes is depicted as an age and stage model with different mental abilities evolving during different stages. This model is intended to help adults guiding young athletes to understand the mental capabilities of the growing youth athlete more completely. Supported by genetic and environmental influences the athlete develops new skills and abilities to layer upon the traits developed during the earlier stages.

A child with an insecure attachment model may present in several ways that can impair social relationships and heighten emotional responses. A common presentation can be a child who has difficulty self-soothing or trusting others and struggles to adapt with cognitive and emotional flexibility. A person might have a secure attachment in some situations while demonstrating an insecure attachment response in a different social context.

Insecure attachment models tend to occur when the primary caretakers are unavailable or inconsistent in helping the young child feel soothed when stressed. In experimental protocols, the toddler with an insecure attachment will respond with anger when the parent returns. In the case of a severe insecure attachment, the child may respond to the returning parent with total indifference, fear, or odd and irregular emotion or behavior when reunited with the caregiver. This lack of trust as a symbolic mental model of attachment can present in young athletes as emotional dysregulation, excessive oppositional behavior, or anger at coaches and other persons in positions of authority. They may be labeled as uncoachable. Attachment models are developed before an individual has explicit memories and cannot recall early past experiences that have shaped their attachment model. The goal here is not to provide an elaborate model of attachment theory and treatment, but to increase awareness that early attachment models can significantly affect a young athlete's social and sports experience which may require greater understanding and special intervention.

In the 1930s, Jean Piaget ⁵ began to describe the stages of cognitive development model with four specific stages occurring during childhood and adolescence. His ideas have become ingrained into thinking about child development and are useful even now in considering how the youth athlete might be capable of thinking at a particular age. He proposed the first stage to be the sensory-motor stage as the infant consolidates control of sensory signals and both fine and gross motor skills. Another influential developmental theorist, Erik Erickson ⁶ created a model of psycho-social development and identified nine different stages occurring in human development from birth through death. The period of life from infancy through toddlerhood was described by two psycho-social stages, first the trust versus mistrust period for the first year of life followed by the autonomy versus shame and doubt phase of human development through toddlerhood. The infant is establishing the internalized attachment model while the toddler is learning to take risks in venturing out from the immediate protection of the parent or caregiver. At this stage, the child seeks approval from the parent and is sensitive to parental rejection. Enriching the young child's experiences to address these developmental challenges benefits mental development. Hence, supporting parents and caregivers to provide a safe, rich, and supportive early environment during the child's early formative years can have dramatic positive implications for the child's future mental development. Interactive programs between parents and young children set the stage for more play interaction with others in the future. ⁴

Play (4–6 years)

The second stage of mental maturity for the potential athlete is the period from about age four through about age 6. The first 3 years are a time of establishing the first connections with the world, the primary caregivers, and the immediate family. Regardless of the child's attachment type and early enrichment, all children must move into this second 3-year Play stage. During this period, the child is emerging from the family and starting to build extrinsic memories. Often a child's first conscious memories are at about age 4. This is a time for venturing forward to become more independent of the family. Language is becoming well-established, and the child's physical skills, such as running, tumbling, balance, and fine motor functioning, are becoming more functional and advanced. This is a time for children to begin to play with other children. Play is primarily for learning. Everything is about play and make believe. Children at this stage have not incorporated logical thought into their worldview. Instead, they watch adults and older children, attempting to emulate observed behavior through their play. They play simple games that are interactive with others and have very few rules. These young children make up rules as they go but have difficulty following the rules of others. They play when it is fun and stop when tired, bored, or frustrated. Play with others starts out as parallel play and gradually evolves into some more complex cooperative play with individuals taking on different roles in the play.

Erickson describes the psycho-social task for this age as the initiative versus guilt stage, a time when children learn to try new activities and experiences and their minds absorb new patterns of behavior as easily as sponges absorb water. This is a very active time in establishing social learning about basic peer interaction. Simultaneously they are becoming very aware of the need for approval from important adults and older children. When an experience is not as expected, anxiety usually occurs. And when persons in authority are not soothing but show disapproval in a repetitive fashion, the child can develop an internalized experience of guilt. While guilt as an emotion can inhibit and control dangerous or socially inappropriate behaviors, when guilt is a predominant emotion it can significantly inhibit a child's willingness to try novel and growth-enhancing experiences by triggering a heightened anxiety state.

Piaget labels this stage in cognitive development as the preoperational stage. This is a time of imagination without the limits of logical consequences. Time is not well understood. Social interactions are usually uncomplicated. It is a magical time when a toy can be anything and play continues with a constantly evolving set of rules, if there are any rules. Winning and losing are not the object of play. Play is the work of children in this age group. It is the important foundational stage for a positive or negative sport experience for a young child. Play gives children the opportunity to practice integrating the various processes of the mind as purposeful acts, often including others in their play. Early physical literacy is evolving at this developmental stage as children begin to develop skills such as running, jumping, and throwing.

In the brain, long neuron fibers are becoming more completely myelinated, allowing for more rapid transmission of neurological signaling. Brain white matter growth is rapid in this stage with significant growth in fiber cross section and moderate growth in fiber density. The white matter growth is most notable in the corticospinal tracts that connect the brain to the body and the corpus callosum tracts that connect the right and left brain hemispheres. There is moderate growth in the limbic structures that control emotions and much less white matter growth in the frontal lobes. The pattern of growth is from lower to higher and posterior to anterior. ⁵ These developments account for the dramatic improvement in motor control and sensory sensitivity as well as the evolution of improved conscious working memory and greater emotional regulation. The mind can take in and process more complex information and act in more complicated and socially appropriate ways.

Skills (7–11 years)

The stage from around 7 to about 11 years is the period when children begin to be more independent in the social world. They may be attending basic schooling and learning cognitive skills such as numbers, letters, reading, and writing. Importantly, they are also learning to follow group rules, adapt to group norms, and follow the directions of teachers and other authority figures. Their activities are more organized both when they are self-directed and when directed by adults or older children. Play and fun are important, but attention span and working memory are critical in learning more complicated tasks. Emotional regulation and emotional awareness are important developing abilities critical in