Aerobic work capacity of mentally retarded boys and girls in junior high schools.

The maximal oxygen uptake (Vo2 max) and ergometer load at a heart rate of 170 beats/min (PWC170) were determined in mentally retarded children (74 boys and 53 girls) of ages 12-15, whose IQ ranged from 36 to 91, and the results were compared with those for normal children. Mentally retarded boys and girls showed significantly inferior body height and weight, but no significant difference was found in skinfold thickness. The mean value of PWC170 for boys and girls was 14.34 kpm/kg/min and 11.31 kpm/kg/min, respectively, significantly less than that of the normal group. The mentally retarded boys had mean VO2 max per unit body weight of 42.4 ml/kg/min, which was significantly less than the 51.2 ml/kg/min of normal boys. The mentally retarded girls had a mean of 33.1 ml/kg/min which was also less than the 41.3 ml/kg/min of normal girls. The correlation coefficient between body weight and PWC170 (kpm/min) was 0.711 and 0.720 for boys and girls, respectively, while that between body weight and VO2 max (liter/min) was 0.641 for boys and 0.656 for girls. No significant correlation was found between IQ and PWC170 (kpm/kg/min) nor between IQ and VO2 max (ml/kg/min) both for boys and for girls. Similarly, no significant correlation was found between mental age and the VO2 max value (ml/kg/min).     

Physical fitness of children aged 5 and 6 years

Maximal oxygen uptake (Vo2 max) of 85 healthy kindergarten children, 46 boys and 39 girls, aged 5 and 6 years, was determined by means of track running. Their physique, skinfold thickness, grip and back muscle strength, and performances of 25 m-run, 50 m-run, standing broad jump, and 5 min-endurance run were also measured. Skinfold thickness of girls was significantly larger than that of boys. Boys were significantly superior to girls in all the motor performances. The Vo2 max per unit of body weight was 49.46 ml/kg/min for boys and 46.30 ml/kg/min for girls, the sex difference being significant at the 0.001 level. The correlation coefficient between Vo2 max per kg body weight and 5 min-endurance run performance was 0.417 for boys and 0.049 for girls, while that between absolute Vo2 max and body weight was 0.899 for boys and 0.563 for girls. The regression equation of the absolute value of Vo2 max (liter/min) on body weight (kg) was: Y=0.051X-0.025 for boys and Y=0.024 + 0.408 for girls, the regression coefficient of boys being twice as large as that of girls. It appears that at ages 5-6 sex differences are exhibited ont only in muscle strength and agility but also in endurance run and aerobic work capacity.     

儿童最大有氧活动能力的发展特征

本文报告了我国４６３名１０－１９岁儿童青少年的最大有氧活动能力的发展特征。在青春早期,男女童的最大吸氧量绝对值均随年龄增长而增加,男童由１．７５升／分增至３．１０升／分,女童由１．４４升／分增至２．０７升／分,女童增长较少;以后女童即稳定于这一水平,男童仍略有增长。按身高及按最大心率计标的相对值与其有相似的特征。按体重和瘦体重计算的相对值,在男女童都未见随年龄增长的规律。男童ＶＯ２ｍａｘ绝对值及各     

Maximal oxygen uptake in Danish adolescents 16-19 years of age

A random sample of schoolchildren, 119 boys and 153 girls, was tested in the fall of 1983. The data presented here are anthropometric data (height, weight, fat % and vital capacity) and oxygen uptake directly measured on a bicycle ergometer. The mean height and weight for boys were 179.1 cm and 67.7 kg, and those for girls were 168.0 cm and 59.6 kg. The mean fat content was 9.1% for boys and 19.1% for girls, and their mean vital capacities were 4.91 and 3.61 respectively. The boys had a high maximal oxygen uptake (51.7 ml X kg-1 X min-1) showing no reduction over the age span studied. The girls' maximal oxygen uptake was lower (overall mean 40.0 ml X kg-1 X min-1) with a small reduction from 16 to 19 years of age. When comparing maximal oxygen uptake per kg lean body mass in the two sexes, the boys had 18.4% higher values than the girls, indicating that girls of this age have the lower fitness level. The results of maximal aerobic power measurement in the boys compare well with findings from other investigations using direct measurements, indicating that the fitness of teenage boys is kept at a high level. Comparable data from various countries for girls show different pictures, but it appears that in general they have a low fitness level.     

38年来济南、青岛儿童少年生长的长期变化

本文分析了济南、青岛1962—2000年7—18岁儿童少年生长发育的长期变化趋势。38年间,济南市7—18岁男女生身高平均增长15 48cm(男)、12 09cm(女),体重平均增长15 76kg(男)、10 01kg(女),胸围平均增长7 88cm(男)、4 10cm(女);青岛市7—18岁男女生身高平均增长17 12cm(男)、13 19cm(女),体重平均增长16 98kg(男)、10 46kg(女),胸围平均增长6 72cm(男)、3 05cm(女)。青岛市男女生身高的增长幅度显著大于济南。     

Growth hormone treatment in short Japanese children born small for gestational age

Recent reports have shown that high-dose growth hormone (GH) treatment in short children born with small for gestational age (SGA) resulted in a pronounced acceleration of linear growth. We describe the results of multicenter trials of recombinant human GH (rhGH) treatment in short SGA children in Japan. Two clinical studies were performed and the results were combined. Study 1 comprised 104 SGA children and study 2 comprised 61 SGA children. The patients were divided into three groups: group 1 consisted of 20 patients (13 boys and 7 girls) who received rhGH 25 microg/kg per day six or seven times per week in the first year and 50 microg/kg per day in the second year and thereafter; group 2 consisted of 48 patients (28 boys, 20 girls) who received rhGH 45/50 microg/kg per day; group 3 consisted of 44 patients (28 boys, 16 girls) who received 90/100 microg/kg per day. The mean increments in height SDS were 0.46, 0.67 and 0.94 SD in boys and 0.49, 0.79 and 0.93 SD in girls in groups 1, 2 and 3, respectively. The mean increment in height SDS at 2 years in group 3 was significantly greater than that in group 1, but it was not significantly different from that in group 2 in boys and girls. Our data demonstrated that high-dose GH administration significantly improved height velocity and height SDS in short SGA children. Additional studies are necessary to optimize a long-term GH treatment regimen and combined luteinizing hormone releasing hormone analog treatment for final height. Careful observation is also necessary to assess the metabolic effects of high-dose GH, especially on carbohydrate metabolism.     

Growth attainments of well-off chandigarh children: A mixed longitudinal study

Distance and velocity pattern of growth for body weight and height of 134 well-off Chandigarh boys aged 9–17 years, and 109 girls aged 9 to 16 years were studied following a mixedlongitudinal growth study design. For both body weight and height pattern-wise, Chandigarh boys showed close similarity with their American counterparts up to about 13 years of age, while girls did so till 12 years. Where after, Chandigarh children remained lighter and shorter than those of American origin and this differential may be explained on racial grounds rather than nutritional ones since all children included in this study remained free from dietary and other health related constraints. Marginally, higher height growth attainments noticed in Chandigarh children in contrast to their other Indian counterparts during initial years of adolescence shows that Chandigarh children are in process of expressing their genetic growth potential to its full which has not yet been fully achieved. The rate (velocity) of weight and height growth in Chandigarh children remained substatially lower than their sex-matched British counterparts throught the period of study. PHV in boys measured 6.4 cm/yr. and 5.4 cm/yr. in girls. It was attained at the age of 11.5 years in girls and 12.5 years in boys. Peak weight velocity in boys averaged 3.7 kg/yr., while it measured 4.6 kg/yr. in girls. In girls (11.5 yr.), PWV too was attained earlier than boys (13.5 yr.) by two years. The shorter height and lighter weight growth attainments noticed in Chandigarh children in contrast to their Western counterparts may be attributed to slower and lesser magnitude peak growth velocities recorded in Chandigarh children. The use of values presented has been recommended to monitor and assess growth attainments of Indian children residing in the Union Territory of Chandigarh.     

Characteristics of cardiac activity in 5- to 7-year-old children during graded exercise

The characteristics of cardiac activity in 5–7-year-old children were studied at rest and during graded veloergometric exercise. The indices of central hemodynamics strongly correlated at rest and the closest correlations were in girls compared to boys. Minute volume increased with an increasing load (from 0.5 to 1.5 W/kg) which could be attributed to an increase in stroke volume. In the groups of 5- to 7-year-old boys and 7-year-old girls the stroke volume increased with an increasing load reaching a maximum at 1.5 W/kg. In the groups of 6-year-old boys and 5-year-old girls the stroke volume increased up to a load of 1.0 W/kg. Heart rate represents another mechanism of cardiac output regulation. The chronotropic response to physical exercise in 5- to 7-year-old children was found to be sex specific, which was especially pronounced at the loads of 1.0 and 1.5 W/kg. Sex difference in the chronotropic heart response to graded physical exercise appeared at the age of 5, and the difference in inotropic response at the age of 7 years substantiates the heterochronous development of chrono- and inotropic cardiac functions.     

Age-dependent heart rate variability in preschool children living under the conditions of the European Arctic region

The results of analysis of specific characteristics of the heart rate variability (HRV) regulation in preschool children living under the Arctic high-latitude conditions are presented. The principal ageand gender-specific differences in the HRV regulation have been inferred from the intergroup evaluations of the HRV indicators in boys and girls. A functional developmental delay has been shown in 2.5-year-old girls compared with boys of the same age group. The applied orthostatic test has shown lower reserve capacities in children of the senior group compared with the junior group. It has been shown that the mechanisms of the regulation of cardiac rhythm in girls experience higher strain during orthostasis as compared with boys. The division of children into age groups with an age difference of one year has allowed the detection of the tendency towards basically different responses to functional loads during orthostasis. The mean HRV values characteristic of four- to six-year-old children living in the Arctic are presented. It has been shown that the children living at middle latitudes have a higher adaptive potential compared with the children living in high-latitude Arctic areas.     

Effect of computer work on the state of physiological functions in children aged 7 to 10 years

We studied the age- and sex-related functional characteristics of the central nervous system (CNS), cardiovascular system (CVS), lability of the visual sensory system, and mental capacity before and after a continuous computer work for 15 min in children aged 7, 8, 9, and 10 years. The results of the research showed that the resistance of the physiological systems of the body to loads associated with computer work increases in primary school children with age. We also observed sex-related differences: many parameters of functional performance during computer work at the age of 8 years were better in girls than in boys, which was due to a higher rate of development; at the age of 10 years, girls had a larger number of adverse changes in the functional state of the body compared with boys, which is possibly due to the onset of puberty.     

Patterns of physical activity among 11 to 16 year old British children.

OBJECTIVE--To examine the patterns of physical activity among British schoolchildren aged 11 to 16 and to assess whether the children experience the intensity and duration of physical activity that are believed to stress the cardiopulmonary system appropriately. DESIGN--Cross sectional study of a sample of children drawn from a larger survey of coronary risk factors in children. Continuous monitoring of heart rate for 12 hour periods on three school days and one Saturday. SETTING--Two communities in Devon. SUBJECTS--266 Children (163 girls, 103 boys) aged 11 to 16 randomly selected from a sample of 707 children. MAIN OUTCOME MEASURES--Percentage of time and number of sustained periods in which heart rate was greater than 139 beats/min. Anthropometric measures and external assessment of sexual maturity with Tanner''s indices. RESULTS--The boys had heart rates greater than 139 beats/min for a significantly higher percentage of time than the girls (p less than 0.01) during the weekday (6.2% v 4.3%) and the Saturday (5.6% v 2.6%). The boys had significantly more five and 10 minute periods with heart rates greater than 139 beats/min than the girls during the Saturday and weekdays and more 20 minute periods during the weekdays. 84 Girls and 37 boys had no 10 minute period with a heart rate greater than 139 beats/min during the three weekdays and 112 girls and 65 boys had no such 10 minute period during the Saturday. No significant relation was detected in either sex between the amount or habitual physical activity (heart rate) and skinfold thickness or maturity group. CONCLUSIONS--British children have surprisingly low levels of habitual physical activity, and many children seldom undertake the volume of physical activity believed to benefit the cardiopulmonary system. Boys are more active than girls. The pubertal stage of development or body fatness, or both, do not seem to be sensitive indicators of physical activity in either girls or boys.     

Maximal oxygen uptake, anthropometry and physical activity in a randomly selected sample of 8 and 13 year old children in Sweden

Maximal oxygen uptake was assessed in 101 randomly selected 8 and 13 year old children. In both age groups a significantly higher aerobic capacity was found in boys than in girls, both in absolute terms and when maximal oxygen uptake was related to body weight, lean body mass and lean leg volume. Among girls, maximal oxygen uptake per kg body weight was lower in the older than in the younger (p less than 0.05). Estimation of spontaneous physical activity, by means of a questionnaire and the actometry method, indicated that physical activity was greater in children with a high than in those with a low aerobic capacity.     

中国汉族儿童生长的长期趋势

本文报告了中国北京、天津、济南、哈尔滨、沈阳、长春、上海、南京、杭州、武汉、广州及成都等12个城市汉族7—18岁儿童生长的长期趋势。 50年代至今,汉族儿童生长的长期趋势是明显的,30年来同年龄儿童身高每10年增长2.66(男)、2.40(女)厘米,体重每10年增长1.64(男)、1.14(女)公斤,近10年来的增长最为显著。生长突增高峰年龄大都提前1—2年。北京、上海、南京、广州、杭州等五所城市自30年代至今,生长长期趋势也是明显的,半个世纪来,每10年增长值,男童身高为1.12—2.66厘米,体重为0.56—1.29公斤,女童身高为1.42—2.67厘米,体重为0.65—1.18公斤。     

Changes in lung, airway, and chest wall function in boys and girls between 8 and 12 yr

Maximum expiratory flows, maximum inspiratory and expiratory pressures, and lung volumes were measured in 248 8-yr-old and 215 12-yr-old healthy school children. Eight-year-old girls had smaller total lung capacity but higher volume-corrected expiratory flows than boys. Maximum expiratory flow and total lung capacity increased more in girls than in boys between 8 and 12 yr. Girls had a greater increase in residual volume (0.23 liter for girls, 0.16 liter for boys) as well as lower maximum expiratory and inspiratory pressures (P less than 0.001). Girls have smaller lung volumes than boys, so one would expect smaller airways in girls, but girls generate greater flows, indicating that their airways are possibly wider than those of boys. There is also evidence of unequal growth of the airways and air spaces between 8 and 12 yr. Chest wall development appears less in girls than boys and the difference becomes more marked at 12 yr.     

Scaling peak VO2 to body mass in young male and female distance runners.

This study examined age- and sex-associated variation in peak oxygen consumption (VO2) of young male and female distance runners from an allometric scaling perspective. Subjects were from two separate studies of 9- to 19-yr-old distance runners from the mid-Michigan area, one conducted between 1982 and 1986 (Young Runners Study I, YRS I) and the other in 1999-2000 (Young Runners Study II, YRS II). Data from 27 boys and 27 girls from YRS I and 48 boys and 22 girls from the YRS II were included, and a total of 139 and 108 measurements of body size and peak VO2 in boys and girls, respectively, were available. Subjects were divided into whole year age groups. A 2 x 9 (sex x age group) ANOVA was used to examine differences in peak VO2. Intraindividual ontogenetic allometric scaling was determined in 20 boys and 17 girls measured annually for 3-5 yr. Allometric scaling factors were calculated using linear regression of log-transformed data. Results indicated that 1) absolute peak VO2 increases with age in boys and girls, 2) relative peak VO2 (ml x kg(-1) x min(-1)) remains relatively stable in boys and in girls, 3) relative peak VO2 (ml x kg(-0.75) x min(-1)) increases throughout the age range in boys and increases in girls until age 15 yr, and 4) peak VO2 adjusted for body mass (ml/min) increases with age in boys and girls. The overall mean cross-sectional scaling factor was 1.01 +/- 0.03 (SE) in boys and 0.85 +/- 0.05 (SE) in girls. Significant age x sex interactions and significant scaling factors between sexes identify the progressive divergence of peak VO2 between adolescent male and female distance runners. Mean ontogenetic allometric scaling factors were 0.81 [0.71-0.92, 95% confidence interval (CI)] and 0.61 (0.50-0.72, 95% CI) in boys and girls, respectively (P = 0.002). There was considerable variation in individual scaling factors (0.51-1.31 and 0.28-0.90 in boys and girls, respectively). The results suggest that the interpretation of growth-related changes in peak VO2 of young distance runners is dependent upon the manner of expressing peak VO2 relative to body size and/or the statistical technique employed.     

Weight loss and the effect on stature in children during a residential intervention program

Weight loss is generally high in residential weight-loss programs but the effect of a large weight loss on linear growth is not known. We report the weight loss and the influence on linear growth in a large group of children during a residential weight-loss program focusing on nutrition and physical activity. In a longitudinal noncontrolled intervention study of 990 overweight children (540 girls) attending the weight reduction program from 1990 to 2001 for about 11 weeks (age: 10-14 years, mean BMI-standard deviation score (SDS) at enrollment: 2.83) weight and height were measured initially and after end of treatment. Weekly measurements of height and weight were performed on 138 children. The children lost on average 9.4 kg, reduced their BMI by 4.5 kg/m(2) and BMI-SDS by 0.98. In a multiple regression analysis (P < or = 0.001) weight loss was higher in boys than girls (1.7 kg), higher if the weight was higher at admission (-0.192 kg/kg at baseline) and was positively associated with duration of stay (-80 g/day). Initially the boys' BMI-SDS was higher than the girls' BMI-SDS (P < or = 0.05) but after 8 weeks of treatment the boys had lower BMI-SDS than the girls. There was no negative effect on linear growth during the treatment; on the contrary, linear growth accelerated during the stay as the average increase in height was 2.38 cm corresponding to 11.4 cm/year. In conclusion the children lost close to 1 kg/week during the stay without any negative effect on linear growth. The cause of the linear growth acceleration needs further investigation.     

Diagnostic utility of a low-dose gonadotropin-releasing hormone test in the context of puberty disorders

OBJECTIVES: The 10-microg gonadotropin-releasing hormone (GnRH) test assesses pituitary gonadotroph responsiveness, whereas the 100-microg dose assesses maximal secretory capacity. Our aims were to establish normative data for the low-dose test in children and to evaluate the test in diagnosing common pubertal disorders. METHODS: We retrospectively classified 107 children who underwent 10-microg GnRH tests into normal prepubertal (20 boys, 10 girls), normal early pubertal (10 boys, 16 girls), constitutional delay of puberty (CDP, 13 prepubertal boys >12 years), hypogonadotropic hypogonadism (HH, 5 prepubertal boys >12 years), central precocious puberty (CPP, 19 girls) or premature thelarche/variant (13 girls). RESULTS: Peak LH response was higher in prepubertal boys >12 years compared with younger boys (p < 0.01) but showed no further change in early puberty. CDP boys had LH responses similar to prepubertal boys >12 years. HH boys showed an absent LH response which diagnosed HH with 100% sensitivity and 96% specificity. Thelarche girls had LH:FSH peak ratios lower than normal prepubertal (p = 0.001), pubertal (p < 0.05) or CPP (p = 0.001) girls. CONCLUSIONS: We have established normative values for the low-dose GnRH test in children. The test successfully differentiated HH from CDP in boys, and contributed to the differential diagnosis of CPP and premature thelarche in girls.     

Energy gain and energy gap in normal-weight children: longitudinal data of the KOPS

Population-based prevention of overweight needs evidence-based goals consistent with our present knowledge about energy gap (i.e., daily imbalance between energy intake and energy expenditure resulting in overweight). Longitudinal data of normal-weight children (1,029 girls and 1,028 boys; Kiel Obesity Prevention Study, KOPS) were used to calculate energy gain (i.e., increase in fat mass (FM) and fat-free mass (FFM)) in normal-weight children staying normal weight (persistent children) or becoming overweight (incident children). Taking into account weight gain in proportion to height gain (normal development) energy gap was calculated from increases in FM and FFM exceeding normal development. Children were divided into two groups and were followed from age 6 to 10 (group A) and 10 to 14 years (group B). FM and FFM were measured. Medians of 4-year BMI- (kg/m(2))/weight changes (kg) were +1.8/+13.2 (A) and +3.0/+18.7 (B) in girls, and +1.6/+12.8 (A) and +2.6/21.7 (B) in boys. Corresponding data for FM/FFM (kg) were +3.1/+10.2 (A) and +5.1/12.7 (B) in girls, and +2.3/10.8 (A) and +3.0/18.6 (B) in boys. The 4-year-incidence of overweight (%) were 9.4 (A) and 5.4 (B) in girls, and 11.0 (A) and 3.8 (B) in boys, respectively. Mean energy gains (kcal/day) were 26.8 (A) and 46.4 (B) in girls, and 22.1 (A) and 32.5 (B) in boys. The 90th percentile of energy gap (kcal/day) in incident children were 58.1 (A) and 72.0 (B) in girls and 46.0 (A) and 53.2 (B) in boys. To prevent overweight in children energy gap should not exceed 46-72 kcal/day.     

Growth charts for Croatian school children and secular trends in past twenty years

The aim of this study was to construct new Croatian growth charts for body height and weight of boys and girls aged 6.5 to 18.5 years and to investigate differences between our and pre-existing studies. Analysis was based on a multistage stratified sample representative for school children aged 6.5 to 18.5, 6046 boys and 5656 girls. Growth reference was constructed using LMS method. Present results demonstrated an increment of body height and weight during the last two decades. Highest increase of body height is in boys aged 13-14 years 6.5 cm, in girls aged 12 years is 5.0 cm. Highest increase of body weight is in 16 year age group of boys 8.7 kg and in 11-12 year age group of girls 5.2 kg. In conclusion, regarding presence of secular trend because previously used growth charts in Croatia are obsolete.     

Interrelationship of indices of body composition and zinc status in 11-yr-old New Zealand children

Serum zinc and hair zinc concentrations of some New Zealand children aged 11 yr, were examined in relation to selected anthropometric indices. Serum zinc concentrations (n=453) in boys and girls were similar and were unrelated to anthropometric indices and hair zinc concentrations. Mean hair zinc concentration (n=620) of the girls was higher than that for the boys (2.95±0.49 vs 2.46±0.47 μmol/g; p<0.001). Correlation analysis demonstrated that, for the boys, all the studied anthropometric indices, with the exception of height, were significantly related to hair zinc concentration and that the confounding effects of mid-parent height and the timing of the adolescent growth spurt was small. Results for the girls were similar but less significant. Dichotomizing the hair zinc results divided both the boys and girls into two groups: those with hair zinc <2.44 μmol/g were heavier (girls, 39.0 vs 35.2 kg; boys, 36.6 vs 34.7 kg) and fatter (mid-upper-arm fat area: girls, 15.2 vs 12.0 cm²; boys, 11.1 vs 9.5 cm²) compared to their counterparts with hair zinc >2.44 μmol/g. The results demonstrate that in these healthy New Zealand children, those with lower hair zinc concentrations are fatter and heavier than their high-hair-zinc counterparts.