Physical activity and children

Exercise in children with common congenital heart lesions: balancing benefits with risks

Children with corrected common congenital heart lesions are often withheld from regular exercise by their parents. While there are some modest risks with exercise, they should be seen in perspective, and the life-long benefits of regular exercise on general health, mood and well-being should be emphasised.

Fatness is not a factor of fitness: analysis of cardiorespiratory data from healthy children over an 8-year period

PURPOSE

To evaluate exercise performance and body mass index in healthy children over an 8-year period in order to determine whether cardiorespiratory fitness has decreased relative to changes in body mass index in our patient population.

METHOD

This study is a retrospective review of anthropometric and cardiorespiratory fitness data from our hospital's Exercise Physiology Laboratory's database on 1201 healthy children (6-18 years) with structurally normal hearts who performed one cycle ergometry test between 1999 and 2006. Subjects were stratified by gender and age. Body mass index was compared between 1999-2002 (Early Group) and 2003-2006 (Late Group) and with national averages. Exercise outcome variables were maximal oxygen consumption, anaerobic threshold, physical working capacity indexed to body weight. Analysis of variance was used to detect differences between groups for each outcome variable.

RESULTS

Body mass index was not significantly different from national data (p-value equals 0.79) or between groups. A negative trend (p-value greater than 0.15 less than 0.20) was observed among most indices of exercise performance between Early and Late Groups. Significantly lower anaerobic threshold was found among males between Early and Late Group (25.7 plus or minus 0.9 versus 23.4 plus or minus 1.6 millilitres per kilogram per minute, p-value less than 0.01), and in physical working capacity among females between Early and Late Groups (2.9 plus or minus 0.1 versus 2.7 plus or minus 0.1, p-value less than 0.05).

CONCLUSIONS

Cardiorespiratory fitness in males and working capacity in females declined over time independent of body mass index. This suggests that other measures may need to be evaluated for promotion of overall cardiovascular health.

Motor fitness in Dutch youth: differences over a 26-year period (1980-2006)

This study aimed to compare neuromotor fitness test scores of 9-12-year-old Dutch youth in 2006 with scores of same aged children in 1980. Body height, body weight and performance on neuromotor fitness test items were measured in 2050 Dutch children from 9 to 12 years in 2006 and were compared with data of 2603 same aged Dutch children measured in 1980 with the same neuromotor fitness test battery. Dutch 9-12 year olds in 2006 were significantly taller and heavier than their peers in 1980. Age- and sex-specific performance on almost all neuromotor fitness test items was significantly worse in 2006. Thus, our data suggest that neuromotor fitness of Dutch youth has significantly decreased over the past 26 years.

Correlates of Exercise Participation in Adolescents

OBJECTIVE

The purpose of this analysis was to determine correlates of exercise participation among adolescents.

DESIGN

A secondary analysis was conducted of data from a cross-sectional survey of 300 adolescents seen at an urban clinic. Using descriptive statistics and path analysis, we examined the direct and indirect effects of independent variables on exercise participation.

RESULTS

Independent variables accounted for 15% of variance in exercise participation. In gender-stratified models, independent variables explained 18% of the variance for females. Older females were associated with lower exercise participation scores (beta=-.273, p<.001). Adolescent females who reported a strong relationship with parent(s) reported higher exercise participation scores (beta=.146, p<.05). Females with higher perception of environmental opportunities for exercise were associated with higher exercise participation (beta=.180, p<.05). Depressive symptoms had the strongest indirect effect (beta=-.10) on exercise participation via behavior-specific cognitions/affect factors among females.

CONCLUSION

The results support that interventions to increase exercise should focus on older female adolescents. Providing information about environmental opportunities for exercise, enhancing relationship with parents, and intervening with adolescents at risk for depression might improve exercise rates in female adolescents.

Responses of non-obese white children to treadmill exercise

OBJECTIVE

To determine the response to maximal treadmill exercise with the Bruce protocol in a cohort of healthy non-obese American children and adolescents.

STUDY DESIGN

A retrospective review of treadmill exercise studies on 347 white American children (188 boys, 159 girls) aged 5 to 18 years was performed with metabolic criteria to verify maximal exercise effort. Data on exercise endurance time, heart rate, blood pressure, and metabolic variables were assessed and compared between age groups and sexes by unpaired t testing and analysis of variance.

RESULTS

Exercise endurance time was lower in all age groups when compared with earlier published data. Girls had a lower endurance time than boys at all ages. There was no significant difference in maximum heart rate with respect to age or sex. The maximum systolic blood pressure and diastolic blood pressure increased with increasing age in both boys and girls. Boys had significantly higher maximum systolic blood pressure and diastolic blood pressure after 13 years of age. The maximum absolute oxygen consumption and indexed oxygen consumption showed similar trends for both sexes.

CONCLUSION

Lower exercise endurance times are seen despite physiologic evidence of maximal effort, raising the possibility that cardiovascular conditioning is reduced in contemporary American children.

Physical activity, obesity, and cardiovascular risk factors in children. The Belgian Luxembourg Child Study II

Physical activity was measured in relation to cardiovascular (CV) risk factors in a randomly selected population of 1028 children from Province de Luxembourg in Belgium, a mainly rural area with a high prevalence of such risk factors among adults and children. Physical activity was estimated as participation in sport activities, a major indicator of leisure-time physical activity in schoolchildren, and physical inactivity was estimated as frequency and duration of television (TV) watching. Boys participated more frequently in sport activities than girls did (p = 0.001). A majority of the children watched TV daily. After age adjustment, bodyweight (girls, p < 0.012; boys, p < 0.027) and, in boys, body mass index (BMI) (p < 0.039) were related to days per week of TV watching. No significant relationships with other CV risk factors remained after adjustments for BMI. In analyses of independent contributions of age, TV watching, and sports activity on CV risk factors, age showed highly significant relationships. In boys, TV showed relationships with BMI (p < 0.04) and (borderline) with systolic blood pressure, independent of age and sports activity, whereas the latter was significantly related to subscapular skinfold (p < 0.04) and (borderline) with triceps skinfold and cholesterol. In girls, no significant independent contributions to risk factor associations were found. The father's education was directly associated with sports activities, whereas the mother being a housewife showed negative relationships to physical activity and positive to TV watching in their children, suggesting socioeconomic influence on the activity patterns of children. Furthermore, registrations suggested less physical activity in the most rural part of the area. It is concluded that children in this mainly rural area watch TV frequently. In boys, physical inactivity, measured both as TV watching and as registrations of sports activities, contributes independently to body fat mass. In girls, no contribution or weaker contributions of physical inactivity were found. This suggests that contributory factors leading to obesity might be different in girls and boys.

Guidelines for school and community programs to promote lifelong physical activity among young people. National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and prevention

Regular physical activity is linked to enhanced health and to reduced risk for all-cause mortality and the development of many chronic diseases in adults. However, many U.S. adults are either sedentary of less physically active than recommended. Children and adolescents are more physically active than adults, but participation in physical activity declines in adolescence. School and community programs have the potential to help children and adolescents establish lifelong, healthy physical activity patterns. This report summarizes recommendations for encouraging physical activity among young people so that they will continue to engage in physical activity in adulthood and obtain the benefits of physical activity throughout life. These guidelines were developed by CDC in collaboration with experts from universities and from national, federal, and voluntary agencies and organizations. They are based on an in-depth review of research, theory, and current practice in physical education, exercise science, health education, and public health. The guidelines include recommendations about 10 aspects of school and community programs to promote lifelong physical activity among young people policies that promote enjoyable physical activity and social environments that encourage and enable physical activity; physical education curricula and instruction; health education curricula and instruction; extracurricular physical activity programs that meet the needs and interests of students; involvement of parents and guardians on physical activity instruction and programs for young people; personnel training; health services for children and adolescents; developmentally appropriate community sports and recreation programs that are attractive to young people; and regular evaluation of physical activity instruction, programs, and facilities.

Effect of exercise training on energy expenditure, muscle volume, and maximal oxygen uptake in female adolescents

OBJECTIVES

American female adolescents are at high risk of a physically inactive lifestyle that likely leads to health problems later in life. We hypothesized that a brief program of endurance exercise training in female adolescents would result in increased energy expenditure and quantifiable structural and functional adaptations.

STUDY DESIGN

Forty-four high school girls (aged 15 to 17 years, none were elite athletes) enrolled in a 5-day per week anatomy class for 5 weeks and were randomly assigned to control (n = 22) and training groups. All subjects participated in a 2-hour daily teaching program. During the remaining time (2 hours), the training group members underwent endurance-type training and control group subjects participated in a computer workshop. The intervention was assessed by (1) comparison of total energy expenditure between groups with the doubly labeled water technique, (2) determination of changes in thigh muscle volume by magnetic resonance imaging, and (3) determination of changes in maximal oxygen uptake by use of respiratory gas exchange responses.

RESULTS

Total energy expenditure was significantly greater (15.3%) in the training group compared with the control subjects (p < 0.003). Five weeks of training led to a 4.3% +/- 1% increase in thigh muscle volume (p < 0.0002) and a 12.1% +/- 3.7% increase in maximal oxygen uptake (p < 0.004); there were no changes in the control group. The training effect was most pronounced in the least fit subjects.

CONCLUSIONS

Exercise training programs for female adolescents can be successfully integrated into a high school summer curriculum. Quantifiable, substantial structural and functional responses occur with relatively short periods of training. Approximately 60% of the training response was related to factors independent of muscle size per se. These data may serve to better design physical activity programs for female adolescents.

Effects of secular trends in obesity on coronary risk factors in children: the Bogalusa Heart Study

OBJECTIVE

To determine whether a secular trend toward increased weight gain was present in children examined 11 years apart in the Bogalusa Heart Study and, if present, the association of this trend with the cardiovascular risk status of the children.

STUDY DESIGN

Two biracial cohorts (approximately 65% white, 35% black) were identified. One cohort was examined first in 1973 at 7 to 9 years of age and was reexamined in 1981 (n = 417). The second was examined first in 1984 at the same age and reexamined in 1992 (n = 235). Measurements made at each assessment included age, gender, race, height, weight, blood pressure, and lipoproteins. The two cohorts were then compared.

RESULTS

The two cohorts were comparable at their first assessment. However, at follow-up 8 years later the more recent cohort was 5 to 7 kg heavier without any difference in linear growth; this increased ponderosity was associated with adverse changes in lipids and lipoproteins: the high-density lipoprotein-cholesterol concentration was 0.15 to 0.35 mmol/L (6 to 13 mg/dl) lower, triglyceride values were 0.09 to 0.40 mmol/L (8 to 36 mg/dl) higher, and there were small increases in total cholesterol and low-density lipoprotein-cholesterol concentrations in white girls. Multivariate analyses showed that in the more recent cohort these changes were related more to a change in ponderosity than to ponderosity. Although blood pressure was generally lower in the recent cohort, increasing ponderosity was associated with higher blood pressure.

CONCLUSIONS

There is a secular trend toward increased ponderosity in children examined in the Bogalusa Heart Study. This trend is associated with worsening cardiovascular risk, particularly with regard to lipoproteins.

Dyslipoproteinemia and other risk factors for atherosclerosis in children and adolescents

The early lesions of atherosclerosis in youth are strongly related to antemortem levels of total and low density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, and triglyceride, to ponderal index and to systolic and diastolic blood pressure. The major apolipoproteins of LDL and high density lipoprotein (HDL), apo B and apo A1, respectively, as well as levels of Lp(a) lipoprotein are often abnormal in children born to a parent with coronary artery disease (CAD). Other risk factors for CAD include obesity, high blood pressure, cigarette smoking, diabetes mellitus, positive family history of CAD and physical inactivity. Children from families with premature CAD, familial dyslipidemia or hypertension, and/or two other risk factors should have a lipoprotein profile determined. The first form of treatment is a diet low in total fat, saturated fat and cholesterol, combined with treatment of overnutrition and obesity, if necessary, and regular habits of aerobic physical activity. Children with inherited disorders of LDL metabolism may require the addition of lipid lowering therapy. The early detection and treatment of youth at risk for premature CAD offers the greatest promise to decrease morbidity and mortality.

Relationships between blood pressure and lipids in childhood

This review has discussed the potential interrelationships of elevated blood pressure and lipid abnormalities. Most of the data for this review have been collected in adults, but physiologic and genetic effects may have expression in childhood. Clustering of cardiac risk factors may be mediated by increased levels of insulin. These increased levels of insulin may be genetically determined or may be related to obesity. Recognition of the multiple risk factor phenotype is important, because individuals with multiple risk may have a much higher risk of future coronary events than do individuals with single risk factors. Medical therapy of individuals with multiple risk should be more aggressive than for individuals with single risk factors. Physicians should be cautious about therapy in the pediatric setting because of possible interaction between therapeutic agents and risk factors, however.