Established and recently identified coronary heart disease risk factors in young people: the influence of physical activity and physical fitness

A cohort study of factors influencing the physical fitness of preschool children: a decision tree analysis

Objective

Based on the decision tree model, to explore the key influencing factors of children's physical fitness, rank the key influencing factors, and explain the complex interaction between the influencing factors.

Methods

A cohort study design was adopted. 1,276 children (ages 3-6) from 23 kindergartens in Nanchang, China, were chosen for the study to measure the children's physical fitness at baseline and a year later and to compare the physical fitness scores at the two stages. The study was conducted following the Chinese National Physical Fitness Testing Standard (Children Part); To identify the primary influencing factors of changes in physical fitness, a decision tree model was developed, and a questionnaire survey on birth information, feeding patterns, SB, PA, dietary nutrition, sleep, parental factors, and other relevant information was conducted.

Results

The levels of physical fitness indicators among preschool children showed a significant increase after 1 year. The accuracy of the CHAID model is 84.17%. It showed that 7 variables were strongly correlated with the physical changes of children's fitness, the order of importance of each variable was weekend PA, weekend MVPA, mother's BMI, mother's sports frequency, father's education, mother's education, and school day PA. Three factors are related to PA. Four factors are related to parental circumstances. In addition to the seven important variables mentioned, variables such as breakfast frequency on school day, puffed food, frequency of outing, school day MVPA, parental feeling of sports, father's occupation, and weekend breakfast frequency are all statistically significant leaf node variables.

Conclusion

PA, especially weekend PA, is the most critical factor in children's physical fitness improvement and the weekend MVPA should be increased to more than 30 min/d based on the improvement of weekend PA. In addition, parental factors and school day PA are also important in making decisions about changes in fitness for children. The mother's efforts to maintain a healthy BMI and engage in regular physical activity are crucial for enhancing the physical fitness of children. Additionally, other parental factors, such as the parents' educational levels and the father's occupation, can indirectly impact the level of physical fitness in children.

Examination of Self-Esteem, Body Image, Eating Attitudes and Cardiorespiratory Performance in Adolescents

Self-esteem, body image and eating attitudes are important characteristics regarding adolescent mental health. In our present work, we aimed to investigate these psychological items in adolescent boys and girls examining gender differences and correlations with the BMI-for-age and cardiorespiratory performance. 374 students (209 girls with an average age of 16.4 ± 1.08 years, and 165 boys with an average age of 16.5 ± 1.03 years) underwent investigation using the Rosenberg self-esteem scale, EAT-26 and BAT questionnaires. The BMI-for-age was calculated with BMI growth charts and the cardiorespiratory performance was measured with the 20 m shuttle run test. Our results showed that adolescent girls scored lower self-esteem and higher values for BAT and each scale of eating behaviors, such as uncontrolled eating, cognitive restraints and emotional eating compared to boys despite the fact, that obesity and overweight were more common among boys. No significant correlation was found between BMI and psychological test results in either boys or girls, however, subjective body shape and gender predicted self-esteem and BAT scores and the cognitive restraints in the eating attitudes. Uncontrolled and emotional eating were primarily influenced by gender, in which BMI played only a weaker role. Cardiorespiratory performance was positively associated with self-esteem and body image among boys, and it had a negative correlation regarding BMI in both genders.

Association between Obesity and Overweight and Cardiorespiratory and Muscle Performance in Adolescents

The high prevalence of obesity in childhood and adolescence has major public health consequences, since it is associated with various chronic diseases in the short- and long-term. The goal of our study was to examine the possible association between obesity and overweight and cardiorespiratory and muscle performance during a 4-year follow up period in adolescents. The body mass index (BMI) and physical performance of adolescents (360 girls and 348 boys) between 14-18 years of age was measured twice a year, and the possible correlation between overweight and obesity and cardiorespiratory and muscle performances were investigated. Our results revealed that cardiorespiratory performance increased significantly in boys during the 4 years (p < 0.001), but the aerobic performance of girls only showed seasonal fluctuation. Muscle performance significantly increased both in boys and girls (p < 0.001). Inverse association between obesity and cardiorespiratory and muscle performance was proved. Overweight was also inversely correlated with cardiorespiratory performance, but it demonstrated no correlation with muscle strength. Avoiding increased BMI and decreased physical fitness is essential for adolescents' health to prevent short- and long-term adverse effects.

Aggregation of risk indicators to cardiometabolic and musculoskeletal health in Brazilian adolescents in the periods 2008/09 and 2013/14

OBJECTIVE

To assess the occurrence of an aggregate risk to cardiometabolic and musculoskeletal health of Brazilian adolescents in the period 2008/09 and 2013/14 and to identify whether there are differences in risk between the genders and in these periods.

METHODS

This was a trend epidemiological study with a quantitative approach, consisting of a voluntary sample of adolescents from 16 Brazilian states. Data were extracted from the database of Brazil Sports Project (Projeto Esporte Brasil). Health-related physical fitness was evaluated based on body mass index, cardiorespiratory fitness, flexibility, and abdominal strength/resistance. Descriptive analysis, chi-squared test, and Poisson log regression were used for the statistical treatment.

RESULTS

In the years 2008/09, 14.6% of Brazilian youngsters showed an aggregate risk to cardiometabolic health and 17.1% an aggregate risk for musculoskeletal indicators, whereas in 2013/14, the values of the risk indicators were, respectively 40.0% and 22.4%. It was observed that, in the years 2013/14, the risk to the cardiometabolic health of boys was 2.51 times greater than in 2008/09, while for girls, a three-fold increase in risk was observed. Concerning musculoskeletal health, girls showed a 2.21 risk of being in the risk zone in 2013/14 when compared with 2008/09.

CONCLUSION

The occurrence of an aggregate risk to the cardiometabolic and musculoskeletal health of Brazilian adolescents increased in the 2008/09 and 2013/14 periods. Regarding gender, an increase in the cardiometabolic and musculoskeletal risk between these periods was observed in girls. As for boys, an increase was observed only in cardiometabolic risk.

Designing a physical activity intervention for children with asthma: a qualitative study of the views of healthcare professionals, parents and children with asthma

OBJECTIVES

Qualitative methods were used to examine: (1) the attitudes of health professionals to promoting physical activity for children with asthma; (2) reasons why children with asthma are less active and (3) how a physical activity programme for children with asthma could be designed.

DESIGN

Semistructured interviews were conducted with health professionals, children with asthma and their parents between October 2015 and March 2016. Interviews were transcribed verbatim and thematically analysed.

SETTING

Primary and secondary care in Bristol (UK).

PARTICIPANTS

Interviews were held with 8 primary care practitioners (5 general practitioners, 2 nurse practitioners and 1 practice nurse), 9 parent-child dyads (2 fathers, 7 mothers, 6 sons, 3 daughters) of children aged 6-7 who had asthma and 4 secondary care professionals (2 respiratory consultants, 2 specialist nurses).

RESULTS

Health professionals reported that physical activity was beneficial for children with asthma and if managed appropriately, children with asthma could be as active as children without asthma. Current promotion of physical activity for children with asthma was limited and restricted by NHS staff time, access to inhalers at school and a lack of parental knowledge. Potentially important components of a new programme include parental education on the possibilities of activity for children with asthma and the difference between exercise-induced breathlessness and asthma symptoms. Other important elements include how to use inhalers as a preventive measure, coping with exacerbations and practical solutions (such as clearing sputum), managing transitions from warm to cold climates and general symptom control.

CONCLUSIONS

There is a need to build on current asthma programmes to increase the support for children with asthma to be physically active. Future programmes could consider working more closely with schools, increasing parental knowledge and providing children with practical support to help be physically active.

Chinese city children and youth's walking behavior

PURPOSE

Although walking has been demonstrated as one of the best forms for promoting physical activity (PA), little is known about Chinese city children and youth's walking behavior. The purpose of this study was therefore to assess ambulatory PA behavior of Chinese city children and youth.

METHOD

The daily steps of 2,751 children and youth (1,415 boys, 1,336 girls; aged 9 to 17 years old, M(age) = 154.78 +/- 44.63 months) from 11 cities in China were recorded using ActiGraph GT3X accelerometers for 7 consecutive days.

RESULTS

The most active walking day was on Friday (M +/- SD = 11,183 +/- 5,130 steps), followed by Monday (M +/- SD = 10,780 +/- 4,921), Thursday (M +/- SD = 10,705 +/- 4,607), Tuesday (M +/- SD = 10,687 +/- 5,038), Wednesday (M +/- SD = 10,428 +/- 4,697), Saturday (M +/- SD = 9,734 +/- 5,582), and Sunday (M +/- SD = 9,303 +/- 5,569). Participants walked more steps during weekdays (M +/- SD = 10,615 +/- 4,411) than they did during weekend days (M +/- SD = 9,444 +/- 5,224; t = 15.71, p < .01, d = 0.34); boys walked more steps (M +/- SD = 10,847 +/- 4,322) than did girls (M +/- SD = 9,938 +/- 4,282; t = 4.92, p < .01, d = 0.22). The most active age was 11 years old in boys (M +/- SD = 12,984 +/- 4,897) and 10 years old in girls (M +/- SD = 11,745 +/- 4,721), and older children walked fewer steps. The data suggest that depending on age (9 to 17 years old), a range of 5.71% to 35.73%, 29.70% to 56.65%, and 15.96% to 47.62% boys and 22.86% to 40.14%, 29.41% to 46.26%, and 12.94% to 40.14% girls met 3 different health-related criteria for daily steps, respectively.

CONCLUSION

Boys walked more than girls walked, but a majority of the Chinese city children and youth did not meet the recommended health-related steps/day.

Cardiovascular risk factor investigation: a pediatric issue

OBJECTIVES

To correlate cardiovascular risk factors (e.g., hypertension, obesity, hypercholesterolemia, hypertriglyceridemia, hyperglycemia, sedentariness) in childhood and adolescence with the occurrence of cardiovascular disease.

SOURCES

A systematic review of books and selected articles from PubMed, SciELO and Cochrane from 1992 to 2012.

SUMMARY OF FINDINGS

Risk factors for atherosclerosis are present in childhood, although cardiovascular disease arises during adulthood. This article presents the main studies that describe the importance of investigating the risk factors for cardiovascular diseases in childhood and their associations. Significant rates of hypertension, obesity, dyslipidemia, and sedentariness occur in children and adolescents. Blood pressure needs to be measured in childhood. An increase in arterial blood pressure in young people predicts hypertension in adulthood. The death rate from cardiovascular disease is lowest in children with lower cholesterol levels and in individuals who exercise regularly. In addition, there is a high prevalence of sedentariness in children and adolescents.

CONCLUSIONS

Studies involving the analysis of cardiovascular risk factors should always report the prevalence of these factors and their correlations during childhood because these factors are indispensable for identifying an at-risk population. The identification of risk factors in asymptomatic children could contribute to a decrease in cardiovascular disease, preventing such diseases as hypertension, obesity, and dyslipidemia from becoming the epidemics of this century.

Feasibility trial evaluation of a physical activity and screen-viewing course for parents of 6 to 8 year-old children: Teamplay

BACKGROUND

Many children spend too much time screen-viewing (watching TV, surfing the internet and playing video games) and do not meet physical activity (PA) guidelines. Parents are important influences on children's PA and screen-viewing (SV). There is a shortage of parent-focused interventions to change children's PA and SV.

METHODS

Teamplay was a two arm individualized randomized controlled feasibility trial. Participants were parents of 6-8 year old children. Intervention participants were invited to attend an eight week parenting program with each session lasting 2 hours. Children and parents wore an accelerometer for seven days and minutes of moderate-to-vigorous intensity PA (MVPA) were derived. Parents were also asked to report the average number of hours per day that both they and the target child spent watching TV. Measures were assessed at baseline (time 0) at the end of the intervention (week 8) and 2 months after the intervention had ended (week 16).

RESULTS

There were 75 participants who provided consent and were randomized but 27 participants withdrew post-randomization. Children in the intervention group engaged in 2.6 fewer minutes of weekday MVPA at Time 1 but engaged in 11 more minutes of weekend MVPA. At Time 1 the intervention parents engaged in 9 more minutes of weekday MVPA and 13 more minutes of weekend MVPA. The proportion of children in the intervention group watching ≥ 2 hours per day of TV on weekend days decreased after the intervention (time 0 = 76%, time 1 = 39%, time 2 = 50%), while the control group proportion increased slightly (79%, 86% and 87%). Parental weekday TV watching decreased in both groups. In post-study interviews many mothers reported problems associated with wearing the accelerometers. In terms of a future full-scale trial, a sample of between 80 and 340 families would be needed to detect a mean difference of 10-minutes of weekend MVPA.

CONCLUSIONS

Teamplay is a promising parenting program in an under-researched area. The intervention was acceptable to parents, and all elements of the study protocol were successfully completed. Simple changes to the trial protocol could result in more complete data collection and study engagement.

The effects of aerobic exercise on psychosocial functioning of adolescents who are overweight or obese

OBJECTIVES

To evaluate effects of stationary cycling to music versus interactive video game cycling on psychosocial functioning in obese adolescents.

METHODS

30 obese adolescents aged 12-17 years were randomized to twice weekly laboratory-based sessions of stationary cycling to music or interactive video game cycling for a 10-week trial. Participant's self-reported measures of scholastic competence, social competence, athletic competence, body image, and self-esteem were obtained. Aerobic fitness and body composition were directly measured.

RESULTS

Although no differences emerged between exercise groups over time, when collapsed across exercise modality, significant pre-post improvements were found for body image, perceived scholastic competence and social competence. Changes in aerobic fitness, but not body composition, were positively associated with psychosocial functioning.

CONCLUSIONS

Aerobic exercise was associated with improvements in body image, perceived academic performance, and social competence in obese adolescents, and these psychological benefits were related to improved aerobic fitness but not changes in body composition.

Hypercholesterolemia increases mitochondrial oxidative stress and enhances the MPT response in the porcine myocardium: beneficial effects of chronic exercise

Hypercholesterolemia has been suggested to have direct negative effects on myocardial function due to increased reactive oxygen species (ROS) generation and increased myocyte death. Mitochondrial permeability transition (MPT) is a significant mediator of cell death, which is enhanced by ROS generation and attenuated by exercise training. The purpose of this study was to investigate the effect of hypercholesterolemia on the MPT response of cardiac mitochondria. We tested the hypothesis that familial hypercholesterolemic (FH) pigs would have an enhanced MPT response and that exercise training could reverse this phenotype. MPT was assessed by mitochondrial swelling in response to 10-100 μM Ca(2+). FH pigs did show an increased MPT response to Ca(2+) that was associated with decreases in the expression of the putative MPT pore components mitochondrial phosphate carrier (PiC) and cyclophilin-D (CypD). FH also caused increased oxidative stress, depicted by increased protein nitrotyrosylation, as well as decreased levels of reduced GSH in cardiac mitochondria. Expression of the mitochondrial antioxidant enzymes manganese superoxide dismutase (MnSOD), thioredoxin-2 (Trx2), and peroxiredoxin-3 (Prx3) was greatly reduced in the FH pigs. In contrast, cytosolic catalase expression and activity were increased. However, chronic exercise training was able to normalize the MPT response in FH pigs, reduce mitochondrial oxidative stress, and return MnSOD, Trx2, Prx3, and catalase expression/activities to normal. We conclude that FH reduces mitochondrial antioxidants, increases mitochondrial oxidative stress, and enhances the MPT response in the porcine myocardium, and that exercise training can reverse these detrimental alterations.

Effects of interactive video game cycling on overweight and obese adolescent health

The purpose of this study was to examine the efficacy of interactive video game stationary cycling (GameBike) in comparison with stationary cycling to music on adherence, energy expenditure measures, submaximal aerobic fitness, body composition, and cardiovascular disease risk markers in overweight and obese adolescents, using a randomized controlled trial design. Thirty overweight (with at least 1 metabolic complication) or obese adolescents aged 12-17 years were stratified by gender and randomized to video game or music condition, with 4 participants (2 per group) failing to complete the twice weekly 60 min sessions of the 10-week trial. The music group had a higher rate of attendance compared with the video game group (92% vs. 86%, p < 0.05). Time spent in minutes per session at vigorous intensity (80%-100% of predicted peak heart rate) (24.9 ± 20 min vs. 13.7 ± 12.8 min, p < 0.05) and average distance (km) pedaled per session (12.5 ± 2.8 km vs. 10.2 ± 2.2 km, p < 0.05) also favoured the music group. However, both interventions produced significant improvements in submaximal indicators of aerobic fitness as measured by a graded cycle ergometer protocol. Also, when collapsed, the exercise modalities reduced body fat percentage and total cholesterol. The present study indicates that cycling to music was just as effective as stationary cycling while playing video games at improving fitness, body composition, and cholesterol profiles in overweight and obese teens, and resulted in increased attendance, vigorous intensity of physical activity, and distance pedaled. Therefore, our data support the superiority of cycling to music and indicate investing in the more expensive GameBike may not be worth the cost.

Secular trends in established and novel cardiovascular risk factors in Welsh 12-13 year olds: a comparison between 2002 and 2007

BACKGROUND

This study examines CVD risk factors trends in Welsh adolescents between 2002 and 2007.

PARTICIPANTS AND METHODS

CVD risk factor data was examined from two cross-sectional studies. The first study (73 participants; aged 12.9 ± 0.3 years) was completed in 2002. The second study (90 participants; aged 12.9 ± 0.4 years) was conducted in 2007. Measurements included body mass index (BMI), waist circumference (WC), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, fibrinogen (Fg) and high-sensitivity C-reactive protein (hs-CRP).

RESULTS

In boys, mean BMI and WC were lower in 2007, although not significantly (p ≥ 0.05). In 2007, there were improvements in mean lipid, Fg and hs-CRP concentrations in both sexes (p < 0.05). In 2002, 42.8% of boys and 34.2% of girls were overweight or obese; in 2007, this was 23.7% and 28.9% for boys and girls, respectively. More adolescents in 2002 exceeded the recommended levels for lipids, Fg and hs-CRP.

CONCLUSION

This is the only study to examine CVD risk factor trends in Welsh adolescents. Although overweight continues to be widespread in 12-13 year olds, this study did not identify significant mean changes in overweight and obesity between 2002 and 2007. Overall, the data presented a positive trend in lipid profile and inflammatory factors.

The Influence of Exercise on Metabolic Syndrome in Youth: A Review

The metabolic syndrome (MetS) is a clustering of dyslipidemia, hypertension, glucose intolerance, and central obesity or waist circumference that places individuals at high risk for developing cardiovascular or heart disease. Although first characterized in adults, it has been found in children, but the definition of MetS in children is still controversial. Although MetS is most closely associated with obesity in children, 2 factors believed to affect MetS are physical activity (PA) and aerobic power or fitness. Studies using accelerometry to estimate PA of children have shown that low levels are associated with increased risk of developing MetS. Conversely, high levels of PA at moderate to vigorous intensities reduce the risk. Similarly, low levels of aerobic fitness increase the likelihood of developing MetS. These effects appear to be independent of obesity. Studies have also shown that interventions that increase PA levels and improve aerobic fitness cause a reduction in MetS risk; however, an exact prescription for exercise cannot be presently provided. This review provides an in-depth analysis of what is presently known about the relationship between MetS and PA and aerobic fitness in children. In addition, information is presented regarding potential mechanisms for exercise to affect the major markers of MetS.

Homocysteine, fibrinogen and anti-ox-LDL antibody levels as markers of atherosclerosis in prepubertal obese children

BACKGROUND

Homocysteine, fibrinogen and antibodies to oxidised LDL were shown to be important markers of atherosclerosis in adults.

AIM

To investigate the levels of these three risk factors in prepubertal obese children.

METHODS

Fasting homocysteine, fibrinogen and antibodies to oxidised LDL, plasma lipids, insulin, HbA1c and blood glucose levels were investigated in 30 prepubertal obese and 28 control children 6-9 years old. Investigations in the obese group were repeated after an oral glucose tolerance test.

RESULTS

Fasting fibrinogen levels of the obese children were found to be significantly higher than those in the controls. Anti-ox-LDL antibody levels increased significantly after an oral glucose tolerance test.

CONCLUSION

Fasting fibrinogen and postload ox-LDL levels which could act as important markers of coronary heart disease in later life could also be important risk factors in prepubertal obese children.

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.

Body fatness and physical activity levels of young children

BACKGROUND

The decline in physical activity levels of young children seems to be combined with a high prevalence of obesity and overweight and a reduction in the participation in organized sport. With the ever-increasing interest in exploring the relationship between physical activity and obesity amongst children, it is important to provide a more precise estimate of both physical activity and body fatness. A significant proportion of previous research on this topic has relied on self-report methods to assess physical activity and body mass index as a proxy for actual body fatness. There is a need to investigate the relationships between physical activity and fatness in children using objective methods.

AIM

This study was conducted in order to explore the relationship between physical activity patterns and percentage body fat amongst a group of primary school children.

SUBJECTS AND METHODS

Forty-seven primary school children (boys, n = 23; girls, n = 24) participated in this study. They were randomly selected from children in years 5 and 6 (9-11 year olds) of four schools drawn from the same catchment area in the city of Birmingham, UK. The frequency, intensity and duration of physical activity were determined using continuous heart rate monitoring from 8:30 am to 8:30pm over three separate days (two weekdays and one weekend day). Percentage body fat was assessed using air displacement plethysmography.

RESULTS

Results indicated that 52% of children did not achieve a single 15-min bout of sustained moderate physical activity over the three days of monitoring. Independent t-tests revealed that girls were significantly fatter (t44 = -3.126, p=0.003) than boys. There was no significant difference (t45 = 0.225, p > 0.05) between boys and girls in accumulated time spent with heart rates above the moderate physical activity threshold. Pearson's product moment correlation coefficients revealed no significant (r= -0.017, p> 0.05) relationship between per cent body fat and average daily time spent in moderate and vigorous activity.

CONCLUSION

Despite the prediction to the contrary, there was no evidence of a significant relationship between percentage body fat of children and time spent in moderate and vigorous activity. Additionally, while there were no significant gender differences in physical activity patterns, children were more physically active during weekdays than weekends.

Action Schools! BC: a school-based physical activity intervention designed to decrease cardiovascular disease risk factors in children

OBJECTIVE

Our primary objective was to determine whether a novel 'active school' model--Action Schools! BC--improved the cardiovascular disease (CVD) risk profile in elementary-school children. Our secondary objective was to determine the percentage of children with elevated CVD risk factors.

METHODS

We undertook a cluster-randomized controlled school-based trial with 8 elementary schools across 1 school year, in British Columbia, Canada, beginning in 2003. Boys and girls (n=268, age 9-11 years) were randomly assigned (by school) to usual practice (UP, 2 schools) or intervention (INT, 6 schools) groups. We assessed change between groups in cardiovascular fitness (20-m Shuttle Run), blood pressure (BP), and body mass index (BMI, wt/ht(2)). We evaluated total cholesterol (TC), total:high-density cholesterol (TC:HDL-C), low-density lipoprotein, apolipoprotein B, C-reactive protein and fibrinogen on a subset of volunteers (n=77).

RESULTS

INT children had a 20% greater increase in fitness and a 5.7% smaller increase in BP compared with children attending UP schools (P<0.05). Forty five percent of children had at least one elevated risk factor (fitness, BP or BMI) at baseline. There were no significant differences between groups for change in BMI or in any of the blood variables.

CONCLUSION

Action Schools! BC was an effective school-based physical activity model for improving the CVD risk profile of elementary-school children. Our multi-component intervention exposed children to fitness enhancing physical activity. It may be important for education stakeholders to adequately resource the delivery of the active school models if cardiovascular health benefits are to be achieved on a population basis.

Fat and carbohydrate metabolism during submaximal exercise in children

During exercise, the contribution of fat and carbohydrate to energy expenditure is largely modulated by the intensity of exercise. Age, a short- or long-term diet enriched in carbohydrate or fat substrate stores, training and gender are other factors that have also been found to affect this balance. These factors have been extensively studied in adults from the perspective of improving performance in athletes, or from a health perspective in people with diseases. During the last decade, lifestyle changes associated with high-energy diets rich in lipid and reduced physical activity have contributed to the increase in childhood obesity. This lifestyle change has emerged as a serious health problem favouring the early development of cardiovascular diseases, insulin resistance or type 2 diabetes mellitus. Increasing physical activity levels in young people is important to increase energy expenditure and promote muscle oxidative capacity. Therefore, it is surprising that the regulation of balance between carbohydrate and lipid use during exercise has received much less attention in children than in adults. In this review, we have focused on the factors that affect carbohydrate and lipid metabolism during exercise and have identified areas that may be relevant in explaining the higher contribution of lipid to energy expenditure in children when compared with adults. Low muscle glycogen content is possibly associated with a low activity of glycolytic enzymes and high oxidative capacity, while lower levels of sympathoadrenal hormones are likely to favour lipid metabolism in children. Changes in energetic metabolism occurring during adolescence are also dependent on pubertal events with an increase in testosterone in boys and estrogen and progesterone in girls. The profound effects of ovarian hormones on carbohydrate and fat metabolism along with their effects on oxidative enzymes could explain that differences in substrate metabolism have not always been observed between girls and women. Finally, although the regulatory mechanisms of fat and carbohydrate balance during exercise are quite well identified, there are a lack of data specific to children and most of the evidences reported in this review were drawn from studies in adults. Isotope tracer techniques and nuclear magnetic resonance will allow non-invasive investigation of the metabolism of the different substrate sources in skeletal muscle.

Physical Activity and Markers of Inflammation and Thrombosis Related to Coronary Heart Disease

Epidemiologic studies have provided strong evidence of the beneficial effects of physical activity in patients with coronary heart disease; however, the mechanisms for the cardioprotective effect of physical activity are not fully understood. The more favorable changes in coronary risk profiles of physically active individuals and the favorable changes observed on several of the established coronary risk factors in exercise intervention studies must play a partial role in that protection. In more recent years, inflammatory and thrombotic factors have been implicated in the development and progression of atherosclerosis. Physical activity has been associated with lower levels of several inflammatory markers; however, the effect of physical activity on coagulation markers remains controversial. The authors summarize the studies on the effect of physical activity on several inflammatory and thrombotic variables. The importance of physical activity in the prevention of cardiovascular disease through modification of the inflammatory and thrombogenic processes is also addressed.

Pedometer determined physical activity levels in primary school children from central England

OBJECTIVE

To assess ambulatory physical activity in school children from central England, to examine any variation in activity between weekdays and weekends and to determine the percentage of children meeting recently identified cut-off steps/day for health.

METHOD

208 British primary school children (101 boys and 107 girls, mean age 9.3+/-0.9 years) from central England wore a sealed pedometer for 4 consecutive days (2 weekend and 2 weekdays) during 2006 from which daily step counts were determined. Data were collected over winter, spring and summer terms. Repeated measures analysis of variance was used to examine potential time (weekend versus weekday), gender and age differences in steps/day.

RESULTS

Children attained significantly higher mean steps/day during weekdays than weekends (p<0.001), and boys attained significantly higher mean steps/day than girls (p<0.05). Mean steps/day values were 13,827 (38,201) and 10,334 (4436) for weekdays and weekends and 12,263 (3789) and 11,748 (3310) for boys and girls respectively. 28.7% of boys and 46.7% of girls met or exceeded the BMI referenced cut-offs for health.

CONCLUSION

Physical activity was greater during weekdays compared to weekends and boys were more active than girls but the majority of children did not meet the health-related cut-off points.

Relationship of physical activity, fitness, and fatness with clustered metabolic risk in children and adolescents: the European youth heart study

OBJECTIVES

To examine the associations of physical activity (PA) at different levels and intensities and cardiorespiratory fitness (CRF) with a clustering of metabolic risk factors in children and adolescents with special consideration of body fat.

STUDY DESIGN

Total PA and intensity levels were measured by accelerometry in children (9 years, n = 273) and adolescents (15 years, n = 256). CRF was measured with a maximal ergometer bike test. Measured outcomes included fasting insulin, glucose, triglycerides, total and high-density lipoprotein cholesterol, blood pressure, and body fat. A metabolic risk score (MRS) was computed as the mean of the standardized outcome scores. A "non-obesity-MRS" was computed omitting body fat from the MRS. Analysis of variance and multiple regressions were used in the analysis.

RESULTS

Total and vigorous PA was inversely significantly associated with MRS in adolescent girls, the group with lowest PA, becoming insignificant when CRF was introduced in the analysis. Significant regression coefficients of total PA and CRF on non-obesity-MRS diminished when body fat was entered in the analysis.

CONCLUSIONS

CRF is more strongly correlated to metabolic risk than total PA, whereas body fat appears to have a pivotal role in the association of CRF with metabolic risk.

Diet, blood lipid profile and physical activity patterns in primary school children from a semi-rural area of Greece

BACKGROUND

Risk factors for heart disease are becoming increasingly prevalent among young populations. The aim of this study was to assess the cardiovascular risk profile of young adolescents living in a semi-rural area of mainland Greece, Volos.

MATERIALS AND METHODS

A total of 198 children (106 females and 92 males) aged 11.6 +/- 0.4 years were randomly recruited.

RESULTS

Mean body mass index was 20.4 +/- 3.5 kg m(-2), while 30.3% of children were overweight and 6.7% were obese; no differences were observed between boys and girls. Mean plasma cholesterol (4.93 +/- 0.75 mmol L(-1)), low-density lipoprotein-cholesterol (3.29 +/- 0.64 mmol L(-1)) and triglyceride (0.97 +/- 0.31 mmol L(-1)) concentrations were above age-specific recommended values. On the other hand, mean high-density lipoprotein-cholesterol was acceptable for 92.3% of the children. Self-reported daily energy intake (8.37 +/- 3.06 MJ) was adequate for age, but intake of fat was high (42.0 +/- 9.2% of energy) and that of carbohydrate was relatively low (44.5 +/- 10.0% of energy). Saturated fat consumption was elevated (15.6 +/- 4.3% of energy), while polyunsaturated fat intake fell short (4.8 +/- 1.6% of energy). The study participants spent 9.60 +/- 6.44 h week(-1) on moderate to vigorous physical activities, while they devoted 16.60 +/- 8.81 h week(-1) to sedentary activities. Boys spent significantly more time than girls on both physical (P < 0.001) and sedentary (P = 0.001) activities. No major gender differences were observed in anthropometric, dietary and plasma lipid parameters.

CONCLUSION

The findings from the present study support the worrisome trends that have been documented in Greek youngsters elsewhere, and predict an unfavourable cardiovascular risk profile for the Greek population in the foreseeable future.

Body mass, fat distribution and blood pressure in Southern Italian children: results of the ARCA project

OBJECTIVE

To investigate the association between the degree of adiposity, assessed using the international reference values for body mass index (BMI) of the International Obesity Task Force (IOTF), the fat distribution pattern and the blood pressure (BP) profile in children.

METHODS

Anthropometric indices and blood pressure were measured in 3923 children aged 6-11 years in southern Italy.

RESULTS

The prevalence of overweight and obesity (by IOTF references) and pediatric hypertension was, respectively: 27, 21 and 10% for boys; 25, 21 and 14% for girls. Body mass index and waist z-scores were the strongest determinants of BP by regression analysis. Overweight and obesity were associated with a greater tendency for central fat deposition and higher BP (waist, cm; boys: 59.2+/-6.0, 69.5+/-7.9, 79.0+/-9.7; girls: 58.8+/-6.5, 68.2+/-7.4, 75.3+/-8.9; SBP/DBP, mmHg; boys: 94/60+/-12/9, 99/62+/-13/8, 103/64+/-15/10; girls: 93/59+/-12/9, 99/62+/-14/9, 101/63+/-14/9; normal weight, overweight and obese, respectively; P<0.0001; M+/-SD), and a higher risk of hypertension (overweight: RR=2.33; 95% CI 1.76-3.08; obesity: RR=3.69; 95% CI 2.78-4.90), independent of age, physical activity, birth weight, parental adiposity and education. Among normal weight children, 99% had waist <85th percentile and 93% were normotensive.

CONCLUSIONS

Overweight and obese children, identified according to the IOTF growth charts, are characterized by a central fat distribution pattern and higher BP.