Language Difficulty at School Entry and the Trajectories of Hyperactivity-Inattention Problems from Ages 4 to 11: Evidence from a Population-Representative Cohort Study

Latent growth curve modelling was used to contrast the developmental trajectories of hyperactivity-inattention (H-I) problems across childhood for children with a language difficulty at the start of school and those with typical language and to examine if the presence of a language difficulty moderates the associations of child, parent and peer predictors with these trajectories. Unconditional and language-status conditional latent growth curves of H-I problems were estimated for a large nationally representative cohort of children, comprising 1627 boys (280 - language difficulty) and 1609 girls (159 - language difficulty) measured at age 4 to 5, 6 to 7, 8 to 9 and 10 to 11. Multiple regression tested interaction between language status and predictors of the level and slope of the trajectory of H-I problems. On average, boy’s H-I behaviours showed temporal stability while for girls H-I decreased over time with a slower rate of decrease with age. For both boys and girls, the levels of H-I problems were persistently elevated for those with a language difficulty compared to their peers. Neither the shape nor rate of change of H-I problems were associated with language status. Child sociability predicted the rate of growth in H-I for boys with a language difficulty but not for other boys. Child prosocial behaviours and parental psychological distress predicted the rate of growth in H-I for girls with a language difficulty but not for other girls. Parental hostility was associated with the rate of growth only for boys with typical language. The findings indicate that having a language difficulty at school entry is associated with persistently higher levels of H-I problems across childhood and moderates the rate of their growth in some circumstances.     

Behavior at 10 and 13 years of age for children with low birth weight

This study was based on data from a longitudinal research program. The cohort consisted of 874 normal children in an entire school grade in a Swedish community. The aim of the study was to investigate the relation between birth weight and behavior at school, for all children and for each sex separately. The results identified specific aspects of behaviour disorder significantly related to low birth weight (LBW) for children at the age of 10 but not at the age of 13. When the sexes were separated, there were no relations between birth weight and deviant behaviour for boys of low birth weight as compared to boys of normal birth weight, while girls of low birth weight showed specific behavioural disorders at age 10 as compared to girls of normal birth weight. For girls reared in families of low parental socioeconomic status, aggressiveness and motor restlessness at age 10 but not at age 13 was also present. Further analyses showed that girls born small-for-gestational age showed lack of school motivation and concentration difficulties both at age 10 and age 13.     

Physical fitness of South African primary school children, 6 to 13 years of age: discovery vitality health of the nation study

Basic physical fitness was measured using 8 different measures for 10,295 South African children and youths (5,611 boys, 4,684 girls) ages 6 to 13 years. These measurements included height, weight, Body Mass Index, standing long jump, shuttle run, sit-and-reach, sit-up (EUROFIT testing battery), and cricket ball throw scores. Due to the effects of earlier apartheid laws on separating communities, it was hypothesized that scores for different ethnic groups may differ. Therefore, in addition to the calculation of basic norms and sex differences, ethnic differences were also tested. Height and weight, relative to age, were different between the various ethnic groups (Black, White, and Mixed ancestry) for boys, with Black boys being shorter and lighter than White boys. There were no differences in sit-and-reach flexibility scores between the groups. With the exception of the cricket ball throw for girls, White children had higher scores in most tests. Although not significantly different from the White children, in the majority of cases, the children of mixed ancestral origin had scores that ranged between the other two ethnic groups. These results suggest a need for encouraging fitness in school children, and the reintroduction of formal physical education into the South African school curriculum, especially into schools in which Black children predominate.     

Normative Developmental Trajectories of Aggressive Behaviors in African American,American Indian,Asian American,Caucasian, and Hispanic Children and Early Adolescents

The current 5-year accelerated longitudinal investigation modeled the developmental trajectories of aggressive behaviors in 10,107 predominantly minority (>70%; African American, American Indian, Asian American, and Hispanic) children and early adolescents (Kindergarten through 8th grade, 49% female youth) from lower to lower-middle socioeconomic strata. Based on a two-part latent growth model, findings suggest that the probability and frequency of aggressive behavior use decreases slightly (linear) through the elementary school years and then increases as children move into middle school (quadratic). Though mean level differences were found across ethnic and racial groups, socioeconomic strata, and particularly by sex at initial status, rates of change over time across all groups were invariant. Findings suggest that potential socialization differences, if any, occur pre-Kindergarten in all groups.     

Laboratory strength measures of talented and less talented Greek children ages 9 to 10 years

The purpose was twofold: (1) to assess whether laboratory tests can distinguish talented groups and less talented groups of children identified by their total scores in a battery of field tests and (2) to evaluate whether scores in field and laboratory tests are correlated. 36 children (ages 9 to 10 years) were divided into groups of higher and lower total scores on standing long jump, medicine ball throw, and sprint. Both groups were tested for maximum isometric force, force produced at the initial 100 msec., reactive force index, drop jump height, squat jump height, and maximum pedaling rate. Analysis showed the talented group had significantly (p < or = .05) higher scores on maximum isometric force, force produced in the initial 100 msec., and drop jump height than less talented children. Moderate to high correlations were found among scores for field performance tests with maximum pedaling rate. In conclusion, the laboratory tests distinguished the talented and less talented children in maximal isometric force, the force produced at the initial 100 msec., the reactive force index, and the drop jump height.     

Sex Differences in the Pathway from Low Birth Weight to Inattention/hyperactivity

Inattention/hyperactivity is a childhood outcome of low birth weight. However, the mechanisms by which low birth weight leads to inattention/hyperactivity are unclear. This study examined arousal, activation, motor speed, and motor coordination as possible mechanisms, attending to sex differences. 823 children (400 males) from Detroit and surrounding suburbs were assessed with the Child Behavior Checklist and the Teacher Report Form and completed experimental tasks to assess vigilance and activation (Continuous Performance Test signal detection parameters) and motor output speed and control (Grooved Pegboard) at 6 years of age. The relationship between birth weight and inattention/hyperactivity was slightly, but not significantly, stronger for boys than for girls. Arousal, motor speed, and motor coordination significantly partially mediated the relationship between birth weight and inattention/hyperactivity for boys and girls. Moderated mediation was found for the pathway between motor coordination and inattention/hyperactivity such that this relationship was stronger for boys than for girls. Sex differences in the associated features of attention symptoms may reflect partially distinct etiological pathways.     

Age, sex, and body mass index in performance of selected locomotor and fitness tasks by children in grades K-2

The purpose of this study was to examine the contributions of 3 predictor variables (age, sex, and body mass index) to performance of 7 fundamental movement skills (locomotor; run, gallop, hop, leap, jump, skip, and slide) and 4 fitness tasks (grip strength, step test, sit and reach, and timed sit-ups) by 65 children in Grades K-2 (M=6 yr.). A multiple regression analysis indicated that running, leaping, and skipping improved with age. No sex differences were observed on any of the seven skills. In terms of the four fitness tasks, age was positively associated with timed sit-ups and grip strength and inversely associated with step-test performance. Sex was associated with step-test and sit and reach performance (girls performed better on both). Finally, body mass index was related to increased grip strength and fewer timed sit-ups.     

Associations Between Multiple Types of Stress and Disordered Eating Among Girls and Boys in Middle School

Stress is common during adolescence, yet no known studies have linked particular types of stress (performance, relationship, education, financial, and family) with disordered eating among adolescents in middle school. The present study investigated sex differences in types of stress and how multiple types of stress were associated with girls’ and boys’ body dissatisfaction, dieting behaviors, and bulimic symptoms. We found that girls reported higher levels of stress than boys and that different associations between stress and disordered eating existed for girls and boys. We also examined a path model for both sexes such that stress first led to body dissatisfaction, which then led to dieting and finally bulimic symptoms. Our model was supported for girls with performance, relationship, and family stress driving the process. For boys, all five types of stress were associated with body dissatisfaction, which was linked with dieting; however, the relation between dieting and bulimic symptoms was not significant. Future research and therapy should focus on the unique experiences of each sex in order to gain a better understanding of the processes involved in coping with stress and promoting healthy development.     

An experimental study of the physical and psychological effects of aerobic exercise on schoolchildren

This study compared the physical and psychological effects of running to those of the normal physical education program of activities among 154 fourth, fifth, and sixth graders who were randomly assigned to conditions within a true experimental design. The running program consisted of three 30-min sessions per week for 12 weeks in lieu of attendance in regular physical education classes. Findings showed that although boys tended to run faster than girls overall and that older children run faster than younger children, running-program participants performed better on an 800-m run, had lower pulse rates, and performed better on a test of creativity than did regular physical education participants. Running boys had less body fat, and running girls had more creative involvement in class. No differences were found on 50-m dash performance or perceptual skill. On total behavior, girls were more self-controlled than boys, and self-concept tended to become less positive with increased grade level. Running performance for 800 m persisted for 5 months among boys in the treatment, but not among girls. Running was judged effective for enhancing the cardiorespiratory health and creativity of school children.     

Contributions of school classification,sex, and ethnic status to adaptive behavior assessment

This study investigated the contributions of school classification (regular, EMR) and sex and ethnic status to domain scores from the Public School Version of the AAMD Adaptive Behavior Scale. For this investigation data were available from a sample of more than 1,600 regular and EMR subjects approximately equally distributed between the sexes among white, black, and Spanish-background subjects from ages 7 to 13. The results replicated earlier findings that domain scores were valid for differentiating among children of different adaptive behavior levels as inferred from school classification status. Ethnic status was not a unique contributor to Part One domain scores when the effects of classification were accounted for. On the Part Two domains, ethnic status was a significant contributor to some domain scores, but not at all age levels. Similarly, sex made few unique contributions to domain scores on Part One of the Scale, but it was a significant factor on some domains of Part Two at some age levels.the author concluded that the Scale was valid for differentiating among pupils assigned to regular and EMR classes from ages 7 to 12. The failure of sex and ethnic status to make contributions to Part One domain scores suggests that there are common expectancies for personal independence and responsibility between boys and girls from different ethnic groups.From the analysis of the contributions of sex and ethnic status to the Part Two domains, the author inferred that difference in environmental tolerance for affective or emotional responses to the school or community environment was a more reasonable explanation than the inference that girls and boys or children grom different cultural backgrounds were inherently different with respect to these behaviors. The Public School Version of the AAMD Adaptive Behavior Scale is valid for assessing adaptive behavior of children in public school and relatively independent of effects attributable to sex or ethnic status.     

Biopsychosocial correlates of weight status perception in Australian adolescents

This study examined the utility of the biopsychosocial model to predict accuracy of weight status perception among Australian adolescents. The factors included in this framework were: age, gender, and BMI-z (biological factors); satisfaction with body weight and shape (psychological factors); socioeconomic status, peer weight (social factors). Cross-sectional data, including measured height and weight, and self-reported weight status, was obtained from 2954 adolescents (mean age = 14.6, 56% male) who participated in the It's Your Move! study. Accuracy of weight status perception was associated with gender, BMI-z, SES, and weight and shape satisfaction. Gender differences in weight status perception were moderated by satisfaction with weight. In boys, weight satisfaction was associated with perceived healthy weight; in girls, it was associated with perceived healthy weight and underweight. Moderately overweight adolescents are most at risk of underestimating their weight status and could benefit from education about the boundaries of the healthy weight range.     

Prevalence of weight reducing and weight gaining in adolescent girls and boys

This is a survey of the prevalence of weight reducing and weight gaining in high school children. Our sample of 1,373 high school girls and boys was geographically, racially, and economically diverse. On the day of the survey, 63% of the girls and 16.2% of the boys reported being on weight reducing regimens; 9.1% of the girls and 28.4% of the boys were trying to gain weight. Most female reducers and male gainers were already normal weight. Compared to other racial groups, whites and Hispanics were more likely to be reducing, whereas blacks were more likely to be gaining. Exercise and moderate caloric reduction were most popular for weight reducing, and a small but significant number were regularly using fasting, vomiting, laxatives, and appetite suppressants. The direction of weight modification for girls and boys conformed to stereotyped physical ideals. The rate of weight reducing in female high school adolescents has increased significantly since similar surveys of American youths 20 years ago.     

Body image and psychological well-being in adolescents: the relationship between gender and school type

Adolescents (N=1281; M age = 15.2 years, SD = 0.51 years) from a state-wide sample of schools provided information about their psychological well-being, family functioning, extraversion, and perceived physical attractiveness and weight, using a questionnaire completed at school. Consistent with previous research, girls were significantly more likely than boys to be dissatisfied with their weight and physical appearance, and these factors explained significantly more variation in self-esteem than in life satisfaction or other measures of psychological well-being. The strong relationship between body dissatisfaction and self-esteem for adolescent girls was not moderated by school type (single sex or educational). However, girls who were dissatisfied but psychologically well adjusted tended to be more extraverted, have more close friends and receive greater family support.     

The development of conceptual interests in young children

We conducted a longitudinal analysis of the relative intensity and duration of interests associated with conceptual domains between the ages of 4 and 6 years, respectively. Results indicated a significant portion of preschool children do sustain an interest in conceptual domains during some portion of their childhood. Expected gender differences were found, with boys more likely to express an interest in a conceptual domain than girls. A latent growth curve analysis revealed that the probability of exhibiting a conceptual interest declined as school began, though the rate of that decline was similar for both boys and girls. Potential explanations for the decrease in conceptual interests as school begins are considered.     

Friendship and loneliness among bullies and victims: Data from seven countries

Research suggests that the relationship between school bullying and its various risk factors should be clearer among girls than boys, and should become stronger with age, as roles within the peer group stabilise. This paper tests this theory by comparing sex, school type, and bully/victim status differences in friendships and playground social interactions, using data from nine surveys in seven countries: China, England, Ireland, Italy, Japan, Portugal, and Spain. A total of approximately 48,000 children completed various translations of the Olweus Bullying Questionnaire. Small but generally consistent main effects were found for sex and school type (boys and primary pupils enjoyed playtimes more and had more friends, but were also more likely to spend playtimes alone). Larger effects were consistently found for bully/victim status (victims were significantly worse off on all the measures in all the samples where a difference was found, while bullies and neutrals did not differ consistently), but the interactions between these factors varied widely between samples and there were few consistent patterns. It is concluded that bullying is a universal phenomenon with many negative correlates for victims and few (if any) for bullies, but that there are cultural variations in the way that bullying is related to sex, age, and social support. Aggr. Behav. 30:71–83, 2004. © 2004 Wiley‐Liss, Inc.     

Eccentric loading and range of knee joint motion effects on performance enhancement in vertical jumping

The aim of the study was to determine the effects of variations in eccentric loading and knee joint range of motion on performance enhancement associated with the stretch-shortening cycle in vertical jumping. Seventeen male elite volleyball players performed three variations of the vertical jump which served as the research model: the squat jump (SJ), countermovement jump (CMJ) and drop jump from a height of 30 cm (DJ30). Knee joint angle (70 degrees and 90 degrees of flexion) at the commencement of the propulsive phase for each jump type was experimentally controlled, with the trunk kept as erect as possible. Force and motion data were recorded for each performance and used to compute a range of kinematic and kinetic variables, including hip, knee and ankle angles, angular velocities, work done, net joint moments and a number of temporal variables. The average of 12 trials for each participant was used in a series of repeated measures ANOVA's (jump xk nee, alpha=.05). From both knee joint angles, an increase in eccentric loading resulted in a significant increase in jump height (DJ30>CMJ>SJ; p<.05). These enhancements were significantly greater (p<.05) for 70 degrees in comparison to 90 degrees of knee flexion. From 70 degrees of knee flexion, these enhancements were due to significant increases in work done at all three joints; while from 90 degrees of knee flexion, only the hip and ankle joints appeared to contribute (p<.05). The amount of enhancement associated with employing the SSC in jumping is dependent upon the interaction of the magnitude of eccentric loading and the range of motion used.     

Body image and eating attitudes among adolescent Chinese girls in Hong Kong

The study investigated the relation between body image and eating attitudes among adolescent girls in Hong Kong. A sample of 358 senior secondary school girls completed the measures assessing body-part satisfaction and behaviors associated with eating. Analysis indicated that even though only 4.8% of the girls were overweight, 85.16% desired to weigh less. These Chinese teenage girls were concerned about their weight, and the desire for slimness was widespread. Correlations indicated that higher Body Mass Index was associated with lower satisfaction with weight. Lower scores on weight satisfaction were associated with higher scores on attitudes of dieting and food preoccupation.     

Diminished heart rate complexity in adolescent girls: a sign of vulnerability to anxiety disorders?

Background and Objectives: Diminished heart rate variability has been found to be associated with high anxiety symptomatology. Since adolescence is the period of onset for many anxiety disorders, this study aimed to determine sex- and anxiety-related differences in heart rate variability and complexity in adolescents.

Methods: We created four groups according to sex and anxiety symptomatology: high-anxiety girls (n?=?24) and boys (n?=?25), and low-anxiety girls (n?=?22) and boys (n?=?24) and recorded their cardiac function while they performed regular school activities. A series of two-way (sex and anxiety) MANOVAs were performed on time domain variability, frequency domain variability, and non-linear complexity.

Results: We obtained no multivariate interaction effects between sex and anxiety, but highly anxious participants had lower heart rate variability than the low-anxiety group. Regarding sex, girls showed lower heart rate variability and complexity than boys.

Conclusions: The results suggest that adolescent girls have a less flexible cardiac system that could be a marker of the girls’ vulnerability to developing anxiety disorders.     

Use of self-organizing maps to study sex- and speed-dependent changes in running biomechanics

BackgroundUp to 79% of runners get injured every year, with higher rates of injuries occurring in females than males. A self-organizing map (SOM) is a type of artificial neural network that can be used to inspect large datasets and study coordination patterns. The purpose of this study was to use an SOM to study the effects of sex and speed on biomechanical coordination patterns.MethodThirty-two healthy runners ran on an instrumented treadmill at their long slow distance speed (LSD) and at speed 30% faster (LSD + 30%). Vertical ground reaction force (vGRF), vertical tibial acceleration, step parameters, electromyograms (EMG) of six lower limb muscles, and joint angles were collected across speeds. Rate of loading (ROL), tibial impact shock (TIS), coupling angle variability (CAV) and movement pattern proportions for hip/knee sagittal and hip frontal / knee sagittal plane couplings, peak EMG, step length, step rate, and knee and ankle joint angle at initial contact were used as an input for the SOM (37 variables).ResultsThe analysis identified four clusters (i.e., running patterns). While males and females showed similar distribution across clusters at LSD (p = .36) and at LSD + 30% (p = .51), females did exhibit a significant (p = .03) shift between clusters as the speed increased from LSD to LSD + 30% whereas males did not (p = .17). The shift was associated with an increase in TIS, ROL, step length, step rate, vastus lateralis EMG, hip flexion/knee extension movement pattern proportion, and a decrease in ST EMG and CAV_IC for hip sagittal/knee sagittal coupling.ConclusionAs running speed increased there was a significant change in the coordination pattern in females, which was characterized by increases in several variables that are purported risk factors for running related injuries.     

初中生友谊质量与孤独感的变化轨迹:一项多元潜变量增长模型分析

为考察初中生友谊质量与孤独感的变化轨迹及两者间的关系,采用关系网络问卷、孤独感量表对西安市的875名初中生（M=12.73±0.18;男生494名）进行三年追踪测量,使用多元潜变量增长模型进行分析。结果发现：（1）初中三年,中学生的友谊质量逐渐提高,孤独感水平逐渐下降;（2）初一时的友谊质量和孤独感水平存在显著的个体差异,初中三年期间二者的发展速度也存在个体差异;（3）初一时的友谊质量可显著预测初一时的孤独感水平（β=-1.77,p<0.001）及随后的发展速度（β=0.20,p<0.05）;（4）男生的孤独感水平初始值高于女生,友谊质量的初始值则低于女生;高SES个体孤独感的起始值高于低SES个体。本研究结果揭示了初中三年期间个体友谊质量与孤独感的动态变化关系及友谊质量对孤独感的预测作用,对改善青少年孤独感的现状有一定的现实指导意义。