Children and adolescents should be encouraged to participate in a variety of sports and activities to develop a wide range of skills while gaining confidence in their abilities to be physically active and achieve specific goals. However, as more boys and girls are participating in organized and recreational sports, there seems to be an increasing number of young athletes who specialize in just one sport starting at an early age or compete for multiple teams year-round without adequate time for recovery between sport seasons. According to some observers, this type of intense training and competition can result in injuries, illness, or burnout, which may have a detrimental effect on the young athlete's ability or desire to participate in sports as an ongoing lifestyle choice (5,8,17).
Millions of school-aged youth in the United States participate in some type of organized or recreational sports program. In addition to interscholastic sports, which are offered in 77% of middle schools and 91% of high schools (14), a growing number of boys and girls participate in highly organized travel teams and "elite" sports clubs that cater to a variety of athletes including dancers, gymnasts, figure skaters, and swimmers. Moreover, the number of private fitness centers that offer specialized training programs for children and adolescents also is increasing. According to the International Health, Racquet and Sportsclub Association, the number of health club members younger than 18 years has grown from 1.8 million members in 1990 to 3.8 million members in 2007 (12).
As more health and fitness centers get involved in the youth fitness market, there is a distinct need for fitness professionals to understand the health-related hazards of overtraining and to become aware of age-appropriate training guidelines. This article will review risks and concerns associated with year-round sports training and will provide sensible guidelines for children and adolescents who want to participate in fitness and sporting activities. Because youth programs should help boys and girls develop a lifelong interest in physical activity, program design considerations for maximizing enjoyment and personal improvement in a positive learning environment will be discussed.
OVERREACHING VERSUS OVERTRAINING
Regular participation in a sports program has the potential to positively influence many physical and psychosocial measures. In addition to favorable changes in aerobic fitness, muscle strength, and selected motor performance skills, sports training provides young athletes with an opportunity to make friends, learn something new, and feel good about their performances. However, sports training for young athletes must be based on the fundamental principles of pediatric exercise science and consistent with the needs, goals, and abilities of each participant. Because young athletes are physically and psychologically less mature than adults, training programs designed for college or professional athletes are potentially injurious to children and adolescents.
If training programs are appropriately designed and sensibly progressed, the acute and chronic adaptations that take place will likely result in meaningful changes in performance. However, if the intensity, volume, or frequency of training exceed the capacity of an athlete, extreme fatigue, injury, or illness can result (5,17). On a short-term basis, excessive training is called overreaching. For example, if a high school swimmer participates in several days of intense and high-volume training (without adequate rest and recovery between workouts), it is likely that performance will begin to decrease. The rationale behind this type of training is to overwork an athlete to build up tolerance and then taper to allow time for recovery and rejuvenation.
Recovery from a brief period of overreaching is typically achieved with a few days of less intense training and rest. Short-term overreaching followed by a tapering period can result in "overcompensation" and an improvement in performance provided that training stimulus and recovery period are consistent with the needs of each athlete (11). In support of these observations, researchers reported that elite junior cross-country skiers could tolerate high-intensity training sessions provided that less intense workouts were systematically incorporated into the sports training program (19). Figure 1 illustrates the overreaching continuum.
Although overreaching is sometimes a planned phase of youth sports programs, overreaching can become overtraining if intense training is continued for a prolonged period without an adequate taper or time for recovery (13). By definition, overtraining refers to a deleterious condition that occurs after repeated strenuous training sessions without adequate rest to allow for proper recovery. Overtraining syndrome (also called burnout) is the condition resulting from overtraining and is typically characterized by a decrease in performance, chronic muscle or joint pain, lack of enthusiasm about practice, and personality changes (5). Unlike overreaching, which typically resolves within a few days, overtraining can last for several months and, in some cases, ruin an athletic career. Doing too much too soon or simply participating in the same sport or activity for a prolonged period may result in overtraining and potentially an overuse injury. For example, high school athletes who are members of the cross-country team in the fall, the indoor track team in the winter, and the outdoor track team in the spring are at increased risk of a tibial or fibular stress fracture.
Typically, overtraining arises when mistakes are made in the design and progression of the training program, which may include both sport-specific (e.g., sport practices and competitions) and non-sport-specific modalities (e.g., strength and conditioning activities) (17). From a real-world perspective, highly motivated young athletes who are pressured by their parents and coaches to outdo predecessors, outshine contemporaries, and outperform competitors may be considered at risk for overtraining syndrome (5). These young athletes need to be mentored and monitored carefully to avoid overparticipation and overtraining.
Overtraining syndrome can result in an overuse injury, which is defined as microtraumatic damage to bone, muscle, or tendon caused by repetitive stress without adequate time for recovery and reparation (5). Children are more susceptible to this type of injury than adults because of the presence of growth cartilage at the following three sites: the growth plate near the ends of long bones, the cartilage lining joint surfaces, and the point at which major tendons attach to bone (17). Because growth cartilage is "prebone," it is more easily damaged by repetitive microtrauma and, therefore, injury to this tissue may result in potentially serious consequences later in life (17).
"Up to 50% of all injuries seen in pediatric sports medicine clinics may be related to overuse" says Lyle J. Micheli, M.D., FACSM, director of Sports Medicine at Children's Hospital Boston. Professionals who work with young athletes need to identify youth at risk of overuse injuries so that correctable risk factors can be identified and treated. Although intrinsic risk factors (e.g., previous injury, poor physical conditioning, and muscle imbalances) and extrinsic risk factors (e.g., improper footwear and training errors) often explain why some young athletes sustain overuse injuries and others remain injury-free throughout the season, a common theme in most overuse injuries is training errors (17). That is to say, highly skilled athletes who suddenly increase the frequency, intensity, or volume of their workouts or unfit athletes who try to play themselves into shape are at an increased risk for injury because their bodies are not prepared for the repetitive stress of sports practice and competition.
A recent analysis of patterns of physical activity among children and adolescents highlighted undesirable trends in measured moderate-to-vigorous physical activity (MVPA) in youth aged 9 to 15 years (18). It was reported that at age 9 years, children engaged in approximately 3 hours per day of MVPA, but by age 15 years, adolescents were only engaging in MVPA for 49 minutes per weekday and 35 minutes per weekend day (18). Although some physical activity is better than none, well-rounded conditioning programs that include strength, power, flexibility, and balance training are needed to produce the anatomical and physiological adaptations that help prevent sports-related injuries in young athletes (1). Thus, the supporting structures of some aspiring young athletes may be ill-prepared to handle the demands of weekly sports practice sessions and weekend competitions. This concern may be particularly important for young female athletes who seem to be more susceptible to knee injuries than young male athletes (15). By addressing risk factors such as poor physical conditioning, some sports medicine professionals believe that both acute and overuse injuries can be reduced by 15% to 50% (17).
Nowadays, it seems that the focus of most youth sports programs is on the development of sport-specific skills rather than on the development of fundamental fitness abilities, such as strength, power, endurance, agility, balance, and coordination. Although some parents and coaches argue that sports specialization is the key to athletic success, broad-based participation in a variety of sports and activities is related more to later sports success than early sports specialization (16). Furthermore, young athletes who participate in a variety of sports seem to suffer fewer injuries than those who specialize in one sport (1,3). Indeed, the American Academy of Pediatrics suggests that sport specialization should be discouraged before adolescence (2). Participation in physical activity should not revolve around one sport, but rather evolve out of varied physical activities that include FUNdamental movement skills (e.g., running, jumping, twisting, hopping, and skipping) and preparatory conditioning that enhance both health- and skill-related components of physical fitness. The physical activity pyramid in Figure 2 illustrates a progression from broad-based participation in lifestyle physical activities to competitive sport.
Because overuse injuries such as tendinitis and stress fractures typically result from too much training or an inappropriate increase in training volume, an important question to consider is "How much training is too much for young athletes?" Although there are no scientific guidelines that answer this question, some sport medicine professionals have suggested limiting one sporting activity to a maximum of 5 days per week with at least 1 day off from any organized activity (5). However, the intensity of each workout as well as subtle changes in the training program also must be considered. For example, high school cross-country runners who switch from running on grass during the summer to running on the road during the fall have increased the stress placed on their developing musculoskeletal system even if the weekly mileage remains the same. Others suggest that careful medical monitoring is needed for young athletes who train more than 18 hours per week (17). Although additional prospective data are needed, it seems reasonable to routinely assess elite young athletes for overuse problems that, when caught early, may be treated nonoperatively with favorable outcomes. It also is desirable for young athletes to take 2 to 3 months off per year from their sport to allow time for physical and psychological recovery from the demands of sports training and competition (5).
Because most physical activity takes places outside of the school setting, qualified fitness professionals are in a unique position to design and implement age-appropriate fitness programs for children and adolescents. In response to the need to better prepare aspiring young athletes for the demands of sports training, several years ago, I developed a program called Sports PREP, which is an acronym for preseason recreation and exercise program. This program is specifically designed to promote motor skill development, enhance physical fitness, and provide an opportunity for each participant to gain confidence in their abilities to be physically active. Unlike other youth programs that isolate health-related components of physical fitness (e.g., aerobic classes), this program integrates both health- and skill-related components of physical fitness into every class. Although a high degree of skill-related fitness is not a prerequisite for a lifetime of physical activity, competence, and confidence in one's ability to perform skills that require balance, coordination, and muscle power can contribute to a child's health and well-being. Indeed, researchers have reported a strong and significant correlation between motor competence and physical fitness in children (9). Others observed that exercises that train the neuromuscular system to function as a unit may reduce the risk of sports-related injuries and enhance athletic performance in young athletes (8,10).
It is important to keep in mind that children and adolescents should learn how to exercise from qualified fitness professionals who understand the physical and psychological uniqueness of children and adolescents. Young participants should not be treated as miniature adults, and youth fitness programs should be consistent with the needs, interests, and abilities of each child. Fitness professionals who work with youth should appreciate the natural activity pattern of children, which is typically characterized by short bursts of moderate to vigorous physical activity interspersed with brief periods of rest as needed (4). Prescribing a program that is inconsistent with a child's needs or abilities will likely undermine the enjoyment of the training experience. Because enjoyment has been shown to mediate the effects of a youth physical activity program (7), all youths should be encouraged to make friends, embrace self-improvement, and feel good about their achievements. In any case, it is always better to underestimate the physical abilities of a child rather than overestimate them and risk negative consequences such as dropout or injury.
Encouraging young athletes to participate in several weeks of fitness conditioning that prepares them for the demands of their sport merits consideration. Although this type of preseason conditioning may seem unnecessary to some observers, participation in fitness conditioning before sports participation has been shown to reduce the incidence of sports-related injuries in young athletes (10). Whereas a training frequency of two or three times a week on nonconsecutive days is typically recommended (8), 1 day off between "hard" workouts may be inadequate for youths who represent different sports teams, specialize in one sport year-round, or participate in other extracurricular conditioning activities. Thus, fitness professionals need to consider the total weekly exercise program when designing fitness workouts for younger populations because of individual differences in stress tolerance. Furthermore, fitness professionals may need to educate parents about the importance of program variation. In some cases, parents may not understand the relationship between exercise and recovery and may want their children to train hard every training session.
Because recovery is an integral part of the training cycle, it is important to balance high-intensity and/or high-volume workouts with less intense training or LIT sessions that facilitate recovery, enhance joint stability, improve range of motion, and reinforce learning of specific movement patterns (8,19). These LIT sessions should be valued by young athletes as an important component of a multifaceted approach to enhancing performance and optimizing recovery. Because the greatest adaptations take place when the muscles have recovered from a previous training session, LIT training enables young athletes to train as hard as possible when they are as strong as possible. Young athletes in the sports PREP program typically perform one or two LIT sessions after a hard training session as part of a periodized workout schedule (8). This type of training facilitates recovery and may reduce the risk of injury while providing an excellent opportunity to reinforce key movement skills and training methods. Whereas specific details of the Sports PREP program are beyond the scope of this article, examples of sample programs for young athletes are available elsewhere (6,8).
Developing fitness and sports programs for young athletes can be a challenging process that involves balancing the demands of training (required for adaptation) with the need for recovery (also required for adaptation). Because overtraining can result in injury, illness, or burnout, fitness professionals have a shared responsibility to provide children and adolescents with fitness experiences that are safe, effective, and enjoyable. Nowadays, qualified fitness professionals have a unique opportunity to design and implement age-appropriate physical activity programs for children and adolescents.
The author thanks Krissy Pennisi for creating the figures in this article.
CONDENSED VERSION AND BOTTOM LINE
Millions of boys and girls participate in organized and recreational sports in the United States. However, there seems to be an increasing number of young athletes who specialize in just one sport starting at a young age or compete for multiple teams year-round without adequate time for recovery between sport seasons. This type of intense training and competition can result in injuries, illness, or burnout. Qualified fitness professionals are in a unique position to design and implement age-appropriate training programs that can reduce the risk of sports-related injuries and enhance athletic performance in young athletes.
1. Abernethy L, Bleakley C. Strategies to prevent injury in adolescent sport: A systematic review. Br J Sports Med
2. American Academy of Pediatrics. Intensive sports training and sports specialization in young athletes. Pediatrics
3. Auvinen J, Tammelin T, Taimela S, Zitting P, Mutanen P, Karppinen J. Musculoskeletal pains in relation to different sport and exercise activities in youth. Med Sci Sports Exerc
4. Bailey R, Olsen J, Pepper S, Porszasz J, Barstow T, Cooper D. The level and tempo of children's physical activities: An observational study. Med Sci Sports Exerc
5. Brenner J. Overuse injuries, overtraining and burnout in child and adolescent athletes. Pediatrics
6. Chu D, Faigenbaum A, Falkel, J. Progressive Plyometric Training for Kids
. Monterey (CA): Healthy Learning; 2006.
7. Dishman R, Motl R, Saunders R, Felton G, Ward D, Dowda M, Pate R. Enjoyment mediates effects of a school-based physical activity intervention. Med Sci Sports Exerc
8. Faigenbaum A, Westcott W. Youth Strength Training: Programs for Health, Fitness and Sports
. Champaign (IL): Human Kinetics; 2009.
9. Haga M. The relationship between physical fitness and motor competence in children. Child: Care Health Dev
10. Hewett T, Myer G, Ford K. Reducing knee and anterior cruciate ligament injuries among female athletes. J Knee Surg
11. Hoffman J. Physiological Aspects of Sports Training and Performance
. Champaign (IL): Human Kinetics; 2002. pp. 262-3.
12. International Health, Racquet and Sportsclub Association/American Sports Data. IHRSA/ASD Health Club Trend Report (1987-2007)
. Cortland Manor (NY): American Sports Data.
13. Kentta G, Hassmen P, Raglin J. Training practices and overtraining syndrome in Swedish age-group athletes. Int J Sports Med
14. Lee S, Burgeson C, Fulton J, Spain C. Physical education and physical activity: Results from the school health policies and programs study 2006. J School Health
15. Louw Q, Manilall J, Grimmer K. Epidemiology of knee injuries among adolescents: A systematic review. Brit J Sports Med
16. Magill R, Anderson D. Critical periods as optimal readiness for learning sports skills. In: Smoll F, Smith R, editors. Children and Youth Sport: A Biopsychosocial Perspective
. Madison (WI): Brown & Benchmark; 1995. pp. 57-72.
17. Micheli L. Preventing injuries in sports: What the team physician needs to know. In: Chan K, Micheli L, Smith A, Rolf C, Bachl N, Frontera W, Alenabi T, editors. F.I.M.S. Team Physician Manual
. 2nd ed. Hong Kong, China: CD Concept; 2006. pp. 555-72.
18. Nader P, Bradley R, Houts R, McRitchie S, O'Brien M. Moderate to vigorous physical activity from ages 9 to 15 years. JAMA.
19. Seiler K, Kjerland G. Quantifying training intensity distribution in elite endurance athletes: Is there evidence for an optimal distribution? Scand J Med Sci Sports