Child Athlete Overview

Melvin H. Williams, Ph.D. Director, Human Performance Laboratory Old Dominion University Norfolk, VA Member, Education Advisory Board Gatorade Sports Science Institute

Key Points

1. The appropriate amount of exercise (neither too little nor too much) is presumably important in the healthful growth and development of children.
2. Many young children and adolescents who are obese, have elevated blood lipid levels, or exhibit other risk factors for cardiovascular disease that may be ameliorated by an appropriate exercise program. These children should be identified early so that suitable education and intervention programs may be planned; public and private schools are proper venues to help children initiate a healthy lifestyle.
3. No sport is risk-free, but sports-related injuries may be minimized with proper preparticipation screening, supervision, regulations, and equipment.
4. Children in weight-dependent sports such as gymnastics may be vulnerable to eating disorders and related consequences, such as premature loss of bone mass.

INTRODUCTION

From a public health perspective, regular exercise can play a major role in preventing several leading degenerative diseases in industrialized societies. Although most degenerative diseases such as coronary artery disease manifest themselves in adulthood, their genesis may be traced to unhealthy behaviors in earlier years. In Healthy Children 2000, the United States Department of Health and Human-Services (1992) noted that childhood is a critical time for developing healthy attitudes and behavior patterns related to tobacco use, diet, physical activity, and other healthrelated behaviors that may persist into adulthood. The proper amount of exercise is presumably important for the optimal development and health status of children. Too much or too little exercise may have some adverse effects (McKeag, 1991 ). In the following segments we shall provide a broad overview of the exercise-related concerns of pediatric health professionals.

CHILDREN, EXERCISE, SPORT, AND APPEARANCE

Children may participate in sports or in exercise fitness programs in an attempt to improve their bodily appearance and thereby enhance their social status. Sports programs for children, particularly girls, have increased extensively over the past two decades, and children appear to be exercising more intensely in order to improve their performance. In certain sports, such as gymnastics and figure skating, children may focus not only on skill improvement but also on weight control as a means to enhance performance. Although increased sports participation and proper weight control are behaviors generally deemed to be desirable for children, there are also reasons for concern if the behaviors are pursued without adequate supervision.

Sports Injuries

Among school-aged children, unintentional injury is the leading cause of morbidity and mortality (Lenaway et al., 1992). Participation in youth sports is relatively safe, but injuries become more prevalent with increasing age, body size, and skill (Landry, 1992; Lenaway et al., 1992). Catastrophic injuries to the head, face, eye, and mouth may be minimized if the requirement for protective devices is enacted by all organizations sponsoring sporting and recreation events that pose risks of injury. Overuse injuries may be caused by excessive exercise. Of special concern is the potential for repeated bouts of long distance running to damage the epiphyseal growth plates in the leg bones of growing children. Although there is some absence of adequate scientific evidence that such running is actually harmful, Rowland (1990) supports the recommendation of the American Academy of Pediatrics that children should avoid participating in long-distance competitive running events that are designed primarily for adults. However, it is the overall mileage logged during training, rather than that covered on the day of competition that matters.

Heat injuries.

In general, prepubescent children can maintain adequate body temperature regulation during exercise in thermoneutral or warm environments but, compared to postpubescents and adults, they are at increased risk for heat injuries while exercising in hot environments. Contributing to this increased risk are the facts that prepubescent children exhibit (1) a greater oxygen cost and heat production for a standard submaximal exercise task; (2) lower sweating rates with similar tasks; (3) lower rates of sweat production per eccrine gland, and (4) lower sensitivities of eccrine glands to a given change in core temperature (Bar-Or, 1988; 1989). Obese or anorexic girls are at special risk for heat-related disorders (Bar-Or, 1988). Furthermore, because prepubertal children rely heavily on increased circulation to the skin to control body temperature, a decreased central circulation as a result of dehydration may impair their ability to perform endurance exercise in the heat (Bar-Or, 1988). Thus, caution should be used in scheduling hot-weather events for children, and fluid replacement during exercise should be of high priority.

Resistance Training Injuries

Increasing numbers of children and adolescents are using resistance training (weight training) to improve their appearance, to increase strength for sports performance, or to help prevent sports-related injuries, even though there is little direct evidence that stronger muscles lead to less frequent or less severe injuries (Rowland, 1990). On the other hand, there is substantial evidence that improper weight training, such as employing maximal lifts, may cause serious musculoskeletal injuries, including ruptured intervertebral discs and damage to epiphyseal growth centers (Risser, 1991; Rowland, 1990; Sale, 1989). Although the incidence of weight-training injuries in children and adolescents is not well documented, several reports indicate that few injuries occur in programs that are carefully supervised and involve proper instruction on technique. Poor technique is the main cause of injury when heavy weights are lifted (Risser, 1991), but children should nonetheless avoid maximal and explosive lifts (Sale, 1989).

Weight Loss

Good nutrition is vital for young athletes undergoing important changes in growth and development. But their desire to achieve a lower than normal body weight to become eligible to compete in a lower weight classification for a specific sport may result in poor dietary practices. Research comparing young female gymnasts at different ages suggests that poor diets may impair growth, but the lower than normal body weights of these gymnasts may simply reflect the fact that youngsters with inherited traits leading to small muscular bodies are more likely to be participants in gymnastic teams and clubs (Benardot & Czerwinski, 1991). Numerous studies have revealed nutrient deficiencies and pathogenic weight-control behaviors in young athletes in weight-classified sports. Unfortunately, there are few data relative to the long-range health effects of such practices (Williams, 1992). On the other hand, anaerobic capacity and other measures of athletic fitness may be impaired by improper eating habits (Williams, 1992).

Girls who are overly concerned about their body weight may find that excessive exercise and/or caloric restriction adversely affects their menstrual status. Although there is no experimental evidence that athletic training delays menarche in girls (Loucks, 1989), exercise and caloric restriction are strongly implicated as causative factors in the etiology of secondary amenorrhea in postpubescent girls. Although one of the benefits of exercise for children is possibly incrementals in bone mass (Slemenda et al, 1991), excessive exercise leading to secondary amenorrhea may lead to bone demineralization (Loucks, 1989) with implications for premature osteoporosis and bone fractures.

Courtesy of the Gatorade Sports Science Institute