Illinois State University The Child and Sport Performance l Is competition physically harmful for the preadolescent?

Illinois State University The Child and Sport Performance l Should preadolescents be allowed to compete in physically demanding activities (e.g. long distance running or strength training)?

Illinois State University The Child and Sport Performance l Physical capabilities of the young exerciser.

Illinois State University The Child and Sport Performance l Differences between young and adult exercisers.

Illinois State University The Child and Sport Performance l The impact of such differences on training and performance.

Illinois State University The Child and Sport Performance Maturational Differences l The peak rate of growth in height occurs at age 12 in girls and 14 in boys. l Full height is typically attained by age in girls and age 18 in boys.

Illinois State University The Child and Sport Performance l The peak rate of weight increase occurs at age 12 in girls and at age in boys. l Muscle mass increases steadily along with weight gain from birth through adolescence.

Illinois State University The Child and Sport Performance l In males, the rate of muscle mass increase peaks at puberty, when testosterone production increases dramatically. l Girls do not experience this sharp increase in muscle mass.

Illinois State University The Child and Sport Performance l Muscle-mass increases in boys and girls result primarily from fiber hypertrophy (increase in cell size) with little or no hyperplasia (increase in cell number).

Illinois State University The Child and Sport Performance l Muscle mass peaks in girls between ages 16 and 20, and in boys between ages 18 and 25, though it can be increased more through diet and exercise.

Illinois State University The Child and Sport Performance l Fat cells can increase in size and number throughout life. l The amount of fat accumulation depends on diet, exercise habits, and heredity.

Illinois State University The Child and Sport Performance l At physical maturity, the body’s fat content averages 15% in males and 24% in females. l The differences are caused primarily by higher testosterone levels in males and higher estrogen levels in females.

Illinois State University The Child and Sport Performance l Bones are formed through ossification, which spreads from primary (diaphysis) and secondary (epiphysis) ossification centers. l Injury at the epiphysis could cause early termination of growth.

Illinois State University The Child and Sport Performance l Competitive baseball, especially the pitching motion, carries the highest risk of epiphyseal injury. l Tennis and swimming also carry higher risks for young athletes.

Illinois State University The Child and Sport Performance l All lung volumes increase until physical maturity. l There is a direct relationship between body size and ventilatory capacities during exhaustive exercise.

Illinois State University The Child and Sport Performance l Blood pressure is also directly related to body size. l It is lower in children than adults but increases to adult levels in the late teen years.

Illinois State University The Child and Sport Performance l During both submaximal and maximal exercise, the child’s smaller heart and blood volume result in a lower stroke volume than in adults. l In partial compensation, the child’s heart rate is higher than an adults.

Illinois State University The Child and Sport Performance l Even with increased heart rate, a child’s cardiac output remains less than an adult’s. l In submaximal exercise, an increase in the a-vO 2 difference ensures adequate oxygen delivery to the active muscles.

Illinois State University The Child and Sport Performance l But at maximal work rates, oxygen delivery limits performance.

Illinois State University The Child and Sport Performance l As pulmonary and cardiovascular function improve with continued development, so does aerobic capacity. l VO 2 max, expressed in L. min -1, peaks between ages 17 and 21 years in males and between 12 and 15 years in females, after which it steadily decreases.

Illinois State University The Child and Sport Performance l When VO 2 max is expressed relative to body weight, it plateaus in males from age 6 to 25 years, but begins its decline at about age 13 in girls. l However, expressing VO 2 max relative to body weight might not provide an accurate estimate of aerobic capacity.

Illinois State University The Child and Sport Performance l Such VO 2 max values do not reflect the significant gains that are noted with both maturation and training.

Illinois State University The Child and Sport Performance l The child’s lower VO 2 max value in (L. min -1 ) limits endurance performance.

Illinois State University The Child and Sport Performance l When expressed relative to body weight, a child’s VO 2 max is similar to an adult’s, yet in activities such as distance running a child’s performance is far inferior to adult performance because of difference in economy of effort.

Illinois State University The Child and Sport Performance l The child’s ability to perform anaerobic activity is limited. l A child has a lower glycolytic capacity, possibly because of a limited amount of phosphofructokinase.

Illinois State University The Child and Sport Performance l Children cannot attain high respiratory exchange ratios during maximal or exhaustive exercise, suggesting less lactate production. l Anaerobic mean and peak power outputs are lower in children than in adults.

Illinois State University The Child and Sport Performance l Laboratory studies indicate that children are more susceptible to injury or illness from thermal stress. l Children are capable of less evaporative heat loss than adults because children sweat less (less sweat is produced by each active sweat gland).

Illinois State University The Child and Sport Performance l Youngsters acclimatize more slowly than adults do.

Illinois State University The Child and Sport Performance l Children appear to have greater conductive heat loss than adults, which should place children at greater risk for hypothermia in cold environments.

Illinois State University The Child and Sport Performance l Until more is known about children’s susceptibility to thermal stress, a conservative approach should be used for children who exercise in temperature extremes.

Illinois State University Summary l Aerobic training in preadolescents does not alter VO 2 max as much as would be expected for the training stimulus, possibly because VO 2 max is dependent on heart size. l But, endurance performance does improve with training.

Illinois State University Summary l A child’s anaerobic capacity is increased with anaerobic training.

Illinois State University Summary l Regular training typically results in: –decreased total body fat –increased fat-free mass –and increased total body mass.

Illinois State University Summary l In general, growth and maturation rates and processes are probably not altered significantly by training.

Illinois State University The Child and Sport Performance l See Strength Training Recommendations for Prepubescent Children.

Illinois State University The Child and Sport Performance l See Basic Guidelines for Resistance Exercise Progression in Children

Illinois State University Summary l Animal studies suggest that resistance training can lead to stronger, broader, more compact bone. l The risk of injury from resistance training in young athletes is relatively low and the programs they should follow are very much like those of adults.

Illinois State University Summary l Strength gains achieved from resistance training in preadolescents result primarily from: –improved motor skill coordination –increased motor unit activation, –and other neurological adaptations.

Illinois State University Summary l Unlike adults, preadolescents who resistance train experience little change in muscle size.