Maximal aerobic power affected by maturation and body growth during childhood and adolescence

This paper examines the development of maximal aerobic power as a function of maturation by a longitudinal study with annual examinations of representative samples of 56 boys and 56 girls in Norway and Western Germany. The age at which occurred peak height velocity (PHV) (i.e. the age at which the greatest height velocity was observed) was used as a reference of biological age and maturation.Before the PHV the mean maximal aerobic power was the same in two cohorts of children both in absolute values as well as in values relative to total and lean body mass. At and after PHV the boys were similar in their absolute values, but the German girls decreased their exercise fitness and became inferior to the Norwegian girls during later adolescence. When related to age of PHV the maximal aerobic power increased during the prepubertal years, mainly as an effect of growth in body size with little or no additional effect of other factors and approached a ceiling level at the end of adolescence.The boys exhibited clearly superior exercise fitness during all years of childhood and adolescence, this being in contrast to the widely accepted concept that no sex difference exists in exercise fitness before puberty.The maximum level for -max, reached at the end of adolescence, averaged 3.2 l/min with a coefficient of variation of about 12% for the boys, and 2.5 l/min for the Norwegian girls and a similar coefficient of variation.As these ceiling values of maximal oxygen uptake agree with published averages for normal young adults representative for the normal population in these two countries, it is suggested that they represent optimal values brought about mainly by normal growth in body size with no or little additional effects of other factors.Dedicated to Prof. M. Máek, Praha, on the occasion of his 60th birthday     

Blood pressure measurement in preschool children: The Hisayama study

Objective: To establish the blood pressure (BP) measurement protocol for Japanese preschool children, systolic BP (K1) and diastolic BP (K4, K5) were measured along with anthropometric values.
Methodology: Commercially available mercury sphygmomanometers were used. In the first group of children (group A), BP was measured in 79 boys and 85 girls using a cuff 9 cm wide and 23 cm long. In the second group (group B), the length and circumference of the upper right arm of 147 boys and 139 girls were measured to select cuffs appropriate for their sizes. Blood pressure measurements were performed twice on the right arm of the children in the seated position at a mean interval of 5 min.
Results: There were no significant differences in the anthropometric values (height, bodyweight, body mass index [BMI], length and circumference of the upper arm) between groups A and B. The BP values at K1, K4 and K5 in the first measurement of group B were 91 ± 9, 54 ± 8, and 48 ± 10 mmHg (boys) and 90 ± 9, 54 ± 8, and 48 ± 12 mmHg (girls), respectively. There were no significant differences between the first and second measurements in both groups, however, there were significant differences in the first and second measurements of K4 between groups A and B. Multiple regression analysis by the stepwise method revealed a strong correlation between K1 and the length of the upper arm in the boys and the bodyweight in the girls: between K4 and the bodyweight in the boys and the BMI in the girls, and between K5 and the height in the boys and the upper arm circumference in the girls.
Conclusions: From these results it would appear that a single measurement is sufficient under appropriate measurement conditions such as rest before measurement and the choice of the cuff size according to the upper arm circumference, and that BP is closely correlated with the anthropometric values in preschool children.     

Height, weight, body mass index and pubertal development references for children of Moroccan origin in The Netherlands

AIM: To provide growth and sexual maturation reference data for Moroccan children living in The Netherlands and to compare them with the reference data of children of Dutch origin. METHODS: Cross-sectional growth and demographic data were collected from 2880 children of Moroccan origin and 14,500 children of Dutch origin living in The Netherlands in the age range 0-20 y. Growth references for length, height, weight, weight-for-height, body mass index (BMI) and head circumference were constructed with the LMS method. Predictive variables for height and BMI were assessed by regression analyses. Reference curves for sexual maturation were estimated by a generalized additive model. RESULTS: Moroccan young adults were on average 9 cm shorter than their Dutch contemporaries. Mean final height was 174.7 cm for males and 161.3 cm for females. Height differences in comparison with Dutch children increase from 2 y onwards. Height SDS was predominantly associated with target height. Compared to Dutch children, maturation started 0.2 and 0.9 y later for girls and boys, respectively. Median age at menarche was 12.9 y, 3.6 mo earlier than in Dutch girls (p = 0.001). BMI of Moroccan children was above that of Dutch children, especially for girls. BMI SDS was associated with birthweight in the age group 0 - < or = 5 y. CONCLUSION: Moroccan children living in The Netherlands are substantially shorter than Dutch children. Girls have higher weight-for-height and BMI for age. Median age at menarche occurs earlier. Given these differences, separate growth charts for the Moroccan children are useful.     

The peak oxygen uptake of healthy Turkish children with reference to age and sex: a pilot study

Maximal oxygen uptake (VO2max) has an important place in the assessment of cardiopulmonary fitness. Currently there is insufficient normative data for Turkish children. With this preliminary study, we aimed to set up a normative data for our lab which may also serve as a basis for future large population based studies in Turkey. We assessed the peak oxygen consumption of 80 healthy Turkish children aged 5-13 years and examined the cardiopulmonary responses to exercise test in relation to their age, sex and body size. Dynamic lung functions were positively and significantly correlated with age. A similar correlation was observed for the peak VO2. A significant positive correlation between peak VO2 and body size was demonstrated only in boys for height. There were no differences in all of the test parameters with reference to sex except in the age group of 13 years. Boys who were 13 years old had higher mean values of maximal voluntary ventilation (MVV), oxygen uptake at anaerobic threshold, peak VO2, and exercise test duration than those of girls of the same age (p < 0.05). VO2 plateau was detected only in 25%, and when two groups with and without VO2 plateau were compared, there were no differences regarding the age, sex, weight, height and exercise test results. Assessment of VO2 by graded exercise stress testing by treadmill is accepted as a safe and effective method of evaluating the physical fitness of children. Current study presents normal data for a limited subpopulation of healthy Turkish children.     

Changes in body composition after a 12-wk aerobic exercise program in obese boys

Previous studies have shown that vigorous aerobic training programs for obese children result in minimal weight changes, and concluded that they may not be beneficial. Weight change alone may not detect important beneficial changes in body composition associated with vigorous training in these children.
Fifteen obese boys (aged 9–12 yr, body mass index (BMI) 31.8±6.5, average percent body fat (%BF) 41±4.2) underwent a supervised aerobic and resistance training program (12 wk, 2 days/wk for 30 min/session), to investigate the effects on weight and body composition.
After the 3-month training period, weight loss averaged only 1.5±1.0 kg (not significant), but total body fat decreased by 4.1±1.8 kg (p<0.05) and fat-free mass (FFM) increased by 2.6±1.1 kg (p<0.05) based on hydrostatic weighing. As a result, %BF fell by 10% (p<0.01). There was a 5.8±2.8 mL/kg/min (p<0.05) increase in peak volume of oxygen uptake (VO₂), along with a 248±120 kcal/d (p<0.05) increase in resting energy expenditure (REE). Activity questionnaires showed a significant increase in high intensity recreational activities (6.5±1.5 vs 3.5±0.5 h physical activity/wk; p<0.01) in the home and a significant decrease in low intensity activities (7±2.0 vs 12±3.5 h TV viewing/wk; p<0.01).
Conclusions: Vigorous supervised aerobic training in obese boys has beneficial effects on body composition, fitness and leisure time activities that are not apparent by measurement of changes in body weight alone.     

Prevalence of overweight and obesity in 5- and 12-year-old Finnish children in 1986 and 2006

Objective: To investigate the prevalence and the trends of overweight and obesity in Finnish 5- and 12-year-old children in 1986 and 2006.
Design: Retrospective cross-sectional study.
Subjects and methods: Anthropometric data were collected retrospectively from health examinations in Tampere and in three rural municipalities. The size of the 5- and 12-year-old cohorts were 2108 in 1986 and 4013 in 2006, respectively. The body mass index (BMI) was calculated. Overweight and obesity was estimated using the International Obesity Task Force cutoff values (ISO BMI).
Results: The prevalence of overweight (ISO BMI >25) and obesity (ISO BMI >30) in 5-year-old boys in 2006 was 9.8% and 2.5% and in girls 17.7% and 2.5%, respectively. At the age of 12 years, the corresponding figures in boys were 23.6% and 4.7% and in girls 19.1% and 3.2%. Between 1986 and 2006, the prevalence of overweight in 12-year-old children had increased 1.8 fold in boys (p < 0.001) and 1.5 fold in girls (p = 0.008). Overweight was significantly more common in rural than in urban areas.
Conclusion: During the last 20 years the prevalence of overweight has markedly increased in 12-year-old Finnish children, but remained nearly unchanged in 5-year-old children.     

Association of physical fitness and body mass index in youth

AIM: The aim of this study was to establish physical fitness (PF) levels in a school population of 11-18-year-old students and analyse differences according to body mass index (BMI) status in overweight METHODS: This is a cross-sectional study. The sample comprises 636 children and adolescents (mean age of 14.5+/-1.5 years), 288 boys (45.3%) and girls 347 (54.7%). Six tests from Fitness-gram battery were used as an objective measure of physical fitness. Overweight/ Obesity status was determined using age and sex adjusted cut-off points. RESULTS: Both girls and boys with obesity performed a significantly reduced number of tests in healthy fitness zone suggesting a decrease of performances in strength and cardiovascular fitness, from normal weight status to overweight and from overweight to obesity. Boys and girls with obesity are likely to be Under HFZ than normal weight. CONCLUSION: The results suggest that obese and overweight children have low PF level compared to normal weight peers. A large number of children with normal weight were identified as well as unfit. These data also showed that a low BMI level would significantly improve some PF component.     

Quantifying the relationships of blood pressure with weight, height and body mass index in Chinese children and adolescents

Aim: The aim of this study was to quantify the relationships of height, weight and body mass index (BMI) with blood pressure (BP) levels in Chinese children and adolescents. Methods: Height, weight, BMI and BP measurements were obtained from a nationally representative sample of 231 227 children aged 7–18 years. Body size measurements were converted to age‐ and sex‐specific standard deviation (SD) scores. The relationships between body size and BP measurements were assessed using linear regression analysis. Results: All body size measurements were significantly associated with BP levels. Systolic BP increased 4.14, 3.70 and 2.88 mmHg in boys and 2.98, 2.63 and 1.87 mmHg in girls, corresponding to 1 SD increase in weight, BMI and height, respectively. A similar pattern was also observed for diastolic BP. After adjustment for height, systolic BP increased substantially with increasing weight (3.96 mmHg/SD increase for boys and 2.92 mmHg for girls). With adjustment for weight, systolic BP increased slightly with 1 SD increase in height (0.27 mmHg for boys and 0.10 mmHg for girls). The strength of the association between a body size measurement and BP varied among different ages, peaked at 10–11 years in girls and around 12–14 years in boys. Conclusions: Weight is the most powerful driving force of BP in children and adolescents, followed by BMI and height. Height has little impact on BP in children with a given weight, while weight has considerable impact on BP in children with a given height.     

经济不发达地区3～9岁儿童血清瘦素水平的变化

目的：了解经济不发达地区3～9岁儿童在营养状况相对较差时血清瘦素的水平及与相关生长发育指标的关系。方法：根据年龄和性别将研究对象分为<6岁女孩组(F36组)、<6岁男孩组(M36)、≥6岁女孩组(F69组)和≥6岁男孩组(M69组)共4组,调查其年龄、体重、身高并计算体重指数(BMI)、体脂百分量(BF%),使用双抗体夹心ELISA法检测瘦素浓度,比较各组间瘦素浓度的差异,同时在各组分析瘦素与各指标间的相关性。结果：①瘦素浓度在同性别比较中,差异无显著性(P>0.05),在同年龄比较中,女孩明显高于男孩(P<0.05);②无论是男孩还是女孩,在3～6岁儿童瘦素与BMI和BF无明显相关(P>0.05),而在6～9岁儿童瘦素浓度与BMI和BF显著相关(P<0.05)。结论：在经济不发达地区3～9岁儿童中瘦素存在性别差异,6～9岁儿童中瘦素与BMI和BF密切相关。     

Ten-year trends in obesity among Israeli schoolchildren: 1990-2000

AIM: To analyze trends in childhood body mass index (BMI) in Israel between 1990 and 2000, and to determine the proportion of obese children using US and population-specific reference values. METHODS: Cross-sectional data from 13 284 second- and fifth-grade schoolchildren were collected, including age, sex, height, weight, country of birth, and time since immigration. Age- and sex-specific BMI means and centiles were calculated, and the prevalence of obesity was determined using Israeli and US reference values. RESULTS: BMI values at the 95th centile increased monotonously over time in all age and sex categories. Between 1990 and 2000, 95th centile values increased by 12.7% and 11.8% among second-grade boys and girls, respectively. Among fifth-grade children, 95th centile values increased by 10.2% and 8.4%, respectively. Among second graders in 2000, 11.4% of both boys and girls exceeded the BMI value recorded at the 95th centile in 1990. Among fifth-graders in 2000, 10.7% of boys and 11.1% of girls exceeded the 1990 BMI reference value (p for all comparisons < 0.001). The proportion of obese children increased over time using both Israeli and US reference values. CONCLUSION: This substantial increase in childhood obesity poses a serious health threat, and requires implementation of suitable public health interventions.     

Effect of gender in response to an aerobic training programme in prepubertal children

The aim of the present study was to investigate the gender effect of an endurance training programme on the maximal oxygen uptake (VO2max) of prepubertal children. The subjects comprised eighty-five 10-11-y-old prepubertal children: 35 (17 girls, 18 boys; EG) were involved in a 13-wk running training programme and 50 (22 girls, 28 boys; CG) served as a control group. Each subject carried out a continuous and progressive cycle ergometer test before and after the 13-wk study period under the same conditions and procedures. Oxygen consumption, carbon dioxide, ventilation and heart rate (HR) were continuously monitored during the test. The training programme consisted of interval and continuous long-distance running (frequency: 3 times a week, duration: 1 h per session, intensity: higher than 80% of maximal HR). V02max significantly increased after the training programme for EG (before = 42.3 +/- 7.7, after = 45.3 +/- 7.5 ml x min(-1) x kg(-1), p < 0.01), while no alterations were noticed for CG (before = 43.1 +/- 6.7, after = 42.6 +/- 7.6 ml x min(-1) x kg(-1), p < 0.01). Such an increase was higher in the girls (+9.1%) than the boys (+4.6%). The lower initial fitness of the girls could explain this, however, because a significant relationship was found between the percentage of VO2max increase after training and the initial VO2max. The present longitudinal study shows that maximal oxygen uptake can increase in prepubertal children after an aerobic training programme and that such an increase is of the same order in boys and girls when the initial aerobic fitness is taken into account.     

Fat patterning of Santhal children: a tribal population of West Bengal, India

A cross sectional study was undertaken to examine the body composition including fat patterning among 1012 Santal children, aged 5-12 years, in Puruliya district of West Bengal, India. The anthropometric variable measured included height, weight and skinfold thickness of triceps and subscapular. The body mass index (BMI) was also calculated. The measurements were used to estimate body fat percent (%BF) and fat-free mass (FFM) from skinfolds. Fat mass and FFM were each divided by height squared to produce the fat mass index (FMI) and fat-free mass index (FFMI). Maximum gaining of %BF and FFM was found at ages 11-12 years in both sexes. Difference of-FFM between 5 and 12 years of age was found to be highest in girls (18.7 kg) than in boys (14.92 kg). Body fat percentage of girls was significantly (p < 0.05) higher (except in 8 and 9 years old) than that of boys. FMI and FFMI of girls showed different pattern than that of boys. FFM and %BF showed significant (p < 0.01) relationship with all anthropometric variables. Results suggests a clear evidence of sexual dimorphism in fat patterning; girls showing a greater subcutaneous adiposity in comparison with boys. FMI and FFMI, both indices indicate an age-and sex-related variation among Santal children. The data of the present study could be serving as reference data in other studies of Santal children.     

Body mass index and overweight in adolescents in 13 European countries, Israel, and the United States

OBJECTIVE: To compare the body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) and the prevalence of BMI at or above the 85th centile and 95th centile (overweight) in adolescents. DESIGN: Cross-sectional, nationally representative school-based surveys in 1997-1998 by means of identical data collection methods. SETTING: Austria, Czech Republic, Denmark, Flemish Belgium, Finland, France, Germany, Greece, Lithuania, Ireland, Israel, Portugal, Slovakia, Sweden, and the United States. PARTICIPANTS: A total of 29 242 boys and girls, aged 13 and 15 years. MAIN OUTCOME MEASURES: The BMI, BMI at or above the 85th centile, and BMI at or above the 95th centile (overweight) from self-reported height and weight. RESULTS: The highest prevalence of overweight was found in the United States and the lowest in Lithuania. On the basis of the study reference standard, the prevalence of overweight (percentage) in the United States was 12.6% in 13-year-old boys, 10.8% in 13-year-old girls, 13.9% in 15-year-old boys, and 15.1% in 15-year-old girls, all significantly increased. Prevalence of overweight in Lithuania was significantly below the expected 5%, with 1.8% in 13-year-old boys, 2.6% in 13-year-old girls, 0.8% in 15-year-old boys, and 2.1% in 15-year-old girls. Relative rankings among countries were similar for BMI at or above the 85th centile, although there were less dramatic differences at this level. CONCLUSIONS: The highest prevalences of overweight were found in the United States, Ireland, Greece, and Portugal.     

Bodyfat percentage in girls increased steadily with age and percentile rank of body mass index

BACKGROUND: The purpose of the present study was to determine the body composition of elementary school children by bioelectrical impedance analysis (BIA) method with a subject in a standing position. The method is frequently used in Japan. The other aim was to evaluate the relationship between the body composition and percentile rank of the body mass index (BMI) in Japanese children. METHODS: The number of subjects were 1042 children (530 boys and 512 girls aged from 6- to 12-years-old) from an elementary school. The bioelectrical impedance (BI) in the standing position was measured late in the morning before lunch. The fat percentage was derived from the body density according to the formula of Brozek et al. Each percentile value of BMI for each age and sex was determined from the frequency table of height and weight published by the Ministry of Education in Japan. RESULTS: The fat percentage in both boys and girls was significantly correlated with the BMI, however, girls showed a closer linear relation than boys. The fat percentage in girls increased steadily with age and percent rank of the BMI. The fat percentage in boys was scattered in a wide range at each percentile rank of the BMI. CONCLUSIONS: The fat percentage measured by the BIA in the standing position is closely associated with the percentile rank of the BMI in elementary school girls. For boys, it will be necessary to compare data among different types of BI measurement methods.     

北京市儿童青少年青春期发育与肥胖相关关系的研究

目的 分析北京市6~18岁儿童青少年青春期发育与超重肥胖的关系。方法 利用2004年北京市儿童青少年代谢综合征调查总样本中19 085名6~18岁儿童青少年的青春期发育、体重指数（BMI）和体脂含量百分比（FMP）等数据。采用女性乳房和男性睾丸容积Tanner分期指标衡量青春期发育，结合个体年龄将群体分为早、晚发育组；以BMI和生物电阻抗法所测FMP作为反映体脂含量的指标；7~18岁人群超重和肥胖的诊断采用中国肥胖问题工作组（WGOC）推荐的中国学龄儿童青少年超重、肥胖筛查BMI值分类标准进行，6岁组采用美国疾病预防与控制中心 2000年发布的儿童超重和肥胖BMI标准第P85和第P95分位值进行诊断；采用多元线形回归、Logistic回归分析早发育与体脂含量和超重、肥胖的相关联系。结果 早发育组的超重（合并肥胖）率和肥胖率均高于晚发育组，女性两组间差异大于男性；控制可能的混杂因素后，女性BMI和FMP与早发育呈正相关（BMI：β=2.25，P<0.001；FMP：β=4.55，P<0.001）；而男性BMI和FMP与早发育的联系相反，早发育组的BMI高于晚发育组，而FMP却低于晚发育组；以晚发育为参照组，控制年龄、城郊居住地等因素的影响后，早发育预测超重、肥胖的OR值（95%CI）：女性为3.39（2.94~3.92）和3.12（2.53~3.85），男性为1.12（0.96~1.31）和1.31（1.06~1.62）。结论 北京市儿童青少年青春期发育与肥胖密切相关，在评价超重、肥胖率及进行不同地区间肥胖流行状况的比较时，要注意青春期发育的效应修正作用。     

Secular trends in body mass index measurements in preschool children from the City of Aachen,Germany

On account of the recent increases in prevalence of childhood obesity in Western countries, the present study tried to verify a secular trend for increasing body mass index (BMI; kg/m(2)) in preschool children in Aachen, Germany. The total sample was based on weight and height data for all 99,500 children of German nationality before enrollment in school in the City of Aachen from 1968-1999. For each year, 10% of the boys and girls respectively, were randomly selected for the analyses. Quantile regression was used to examine the pattern and extent of change in BMI percentiles over this 31-year period. Anthropometric data of a total of 5081 boys and 4863 girls were subjected to quantile regression. While significant increases occurred for any given BMI percentile, the annual increase for both sexes was most prominent in the upper range. No change in body height was observed during the study period. CONCLUSION: preschool children have gained a higher body mass index during the last 30 years. The mechanisms underlying the secular trend towards increasing body mass index seemingly affect children in the upper weight range more than those in the lower range.     

MAXIMAL OXYGEN UPTAKE IN RELATION TO AGE IN BLIND AND NORMAL BOYS AND GIRLS

ABSTRACT. Maximal oxygen uptake (VO₂ max) was measured in 180 children during exhaustive work on a bicycle ergometer. The material comprised 12 blind boys and 11 blind girls (8–14 years) as well as 82 normal boys and 75 normal girls (8–17 years). VO₂ max increased linearly with age in all four groups. In normal girls mature values were reached at the age of 14 years. Normal boys had significantly higher values than normal girls and their VO₂ max increased faster with age. No sex differences in VO₂ max were found in blind children. Normal children had significantly higher values than the blind. VO₂ max/kg was uninfluenced by age in three of the groups: 55, 45 and 37 ml/min/kg in normal boys, blind boys and blind girls, respectively. In normal girls VO₂ max/kg decreased with age from 51 to 42 ml/min/kg. Significant sex differences were found in both normal and blind children. VO₂ max/kg in blind boys was 82% of that of normal boys, while blind girls had significantly lower values than normal girls. Most of these differences were established already at the age of 8 years. It is concluded that the differences in maximal oxygen uptake between normal and blind children are to a high degree due to different levels of physical activity during early childhood.     

Prediction of obesity from infancy to adolescence

Aim: To examine the development of childhood obesity and to determine the earliest age when estimating body mass using only weight and height data is associated with a corresponding estimate at the age of 15. Methods: Subjects included are all children born in 1991 in Östergötland County, Sweden. Weight and height data collected during regular check‐ups at well‐child centres and school health care assessments up to 15 years of age were assembled from health records. Correlations between childhood estimates of body mass and the body mass index (BMI) at 15 years of age were computed pairwise. Correlations with r > 0.5 were defined as reliably strong. Results: Complete data were available for 3579 children (62%). Fewer girls (2.6%; C.I. 1.9–3.3) than boys (4.6%; C.I. 3.7–5.5) were obese at 15 years of age. Correlations with BMI at 15 years of age were strong (significantly higher than 0.5) from 5 years of age. Only 23% of girls and 8% of boys found to be obese at 5 years of age were of normal weight at the age of 15. Conclusion: From 5 years of age, point estimates of body mass using only weight and height data are strongly associated with BMI at the age of 15. More data sources are needed to predict weight trajectories in younger children.     

Predictors of VO2Peak in children age 6- to 7-years-old

This study investigated the predictors of aerobic fitness (VO2PEAK) in young children on a population-base. Participants were 436 children (229 boys and 207 girls) aged 6.7 ± 0.4 yrs. VO2PEAK was measured during a maximal treadmill exercise test. Physical activity was assessed by accelerometers. Total body fat and total fat free mass were estimated from skinfold measurements. Regression analyses indicated that significant predictors for VO2PEAK per kilogram body mass were total body fat, maximal heart rate, sex, and age. Physical activity explained an additional 4-7%. Further analyses showed the main contributing factors for absolute values of VO2PEAK were fat free mass, maximal heart rate, sex, and age. Physical activity explained an additional 3-6%.