Fatness, fitness, and insulin sensitivity among 7- to 9-year-old children

Objective: The purpose of this study was to examine the relationships among fatness and aerobic fitness on indices of insulin resistance and sensitivity in children. Research Design and Methods: A total of 375 children (193 girls and 182 boys) 7 to 9 years of age were categorized by weight as normal‐weight, overweight, or obese and by aerobic fitness based on a submaximal physical working capacity test (PWC). Fasting blood glucose (GLU) and insulin (INS) were used to calculate various indices of insulin sensitivity (GLU/INS), the homeostasis model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI). Surrogate measures of pancreatic β cell function included the insulinogenic index (INS/GLU) and the HOMA estimate of pancreatic β‐cell function (HOMA %B). Results: Insulin sensitivity and secretion variables were significantly different between the normal‐weight children and the overweight and obese subjects. Fasting insulin (FI), HOMA, QUICKI, and INS/GLU were significantly different between the overweight and obese subjects. Likewise, the high fitness group possessed a better insulin sensitivity profile. In general, the normal‐weight–high fit group possessed the best insulin sensitivity profile and the obese‐unfit group possessed the worst insulin sensitivity profile. Several significant differences existed among the six fat‐fit groups. Of particular note are the differences within BMI groups by fitness level and the comparison of values between the normal‐weight–unfit subjects and the overweight and obese subjects with high fitness. Conclusions: The results indicate that aerobic fitness attenuates the difference in insulin sensitivity within BMI categories, thus emphasizing the role of fitness even among overweight and obese children.     

Auditory-motor learning during speech production in 9-11-year-old children

Background

Hearing ability is essential for normal speech development, however the precise mechanisms linking auditory input and the improvement of speaking ability remain poorly understood. Auditory feedback during speech production is believed to play a critical role by providing the nervous system with information about speech outcomes that is used to learn and subsequently fine-tune speech motor output. Surprisingly, few studies have directly investigated such auditory-motor learning in the speech production of typically developing children.

Methodology/Principal Findings

In the present study, we manipulated auditory feedback during speech production in a group of 9–11-year old children, as well as in adults. Following a period of speech practice under conditions of altered auditory feedback, compensatory changes in speech production and perception were examined. Consistent with prior studies, the adults exhibited compensatory changes in both their speech motor output and their perceptual representations of speech sound categories. The children exhibited compensatory changes in the motor domain, with a change in speech output that was similar in magnitude to that of the adults, however the children showed no reliable compensatory effect on their perceptual representations.

Conclusions

The results indicate that 9–11-year-old children, whose speech motor and perceptual abilities are still not fully developed, are nonetheless capable of auditory-feedback-based sensorimotor adaptation, supporting a role for such learning processes in speech motor development. Auditory feedback may play a more limited role, however, in the fine-tuning of children''s perceptual representations of speech sound categories.     

Relation of visual evoked potentials to the integral characteristics of cognitive activity in 8- to 9-year-old children

Amplitude and temporal parameters of evoked potentials (EPs) in response to a checkerboard pattern, picture of a house, the Russian word "dom", meaning house, combination of letters "DMO" and a number of other stimuli, correlated with indices of the verbal, nonverbal, and general intelligence as well as with those of the cognitive style "field dependence-independence". Maximum number of statistically significant correlations was found in the course of comparison of integrative cognitive characteristics and parameters of EPs to stimuli with increased semantic complexity. No interhemispheric differences were found in the character of interrelations between cognitive characteristics and parameters of EPs to verbal and spatially structured stimuli.     

The dependence of the emotional state of 8- to 9-year-old children on the conditions of play]

Dependence was studied of emotional state of children, aged 8-9, on the terms of computer play: without additional instruction (with a strategy typical of the child), at time deficiency and at demonstration of techniques of play without limitation in time. Prior to and during the play the following parameters were recorded: heart rate (HR); frequency of basis tone (Fb.t.) and evaluation of frequency of the first formant (n(0] of the vowel "a" in the word "da" pronounced by the child during the play in response to acoustic signal; reaction time (RT) to acoustic signal; parameters of playing activity and also spontaneous verbal expressions of children. Increase of emotional stress during the play at time deficiency was accompanied by the most expressed changes of HR, RT, Fb.t., worsening of playing activity and the increase of the number of negative emotional reactions. When playing without additional instruction, the children showed the best results of playing activity, accompanied by the least expressed changes of HR and Fb.t. in comparison with the background at the greatest expressiveness of the n(0) change, and predominantly positive emotional reactions. The analysis of the correlation of the motivational and informational characteristics of the studied playing activity allowed to make a conclusion about preferential connection of HR and Fb.t. with the motivational and n(0) with informational components of the playing activity.     

Examining physical activity and inactivity in 9-12 years old children

Information about children's daily physical activity in Eastern-Europe is essential because of the increasing prevalence in overweight and obesity. Sixty-three children (age=11.16 ± 1.10 years; 33 boys and 30 girls) from two public elementary schools had their physical activity objectively measured using uni-axial accelerometer every 5 seconds for five consecutive days (3 weekdays, 2 weekend days). After data cleaning, 10 children were excluded from database. There were no significant differences in boys' and girls' BMI (17.6 ± 2.2 vs. 17.1 ± 2.4) and BF% (18.0 ± 5.2 vs. 19.4 ± 5.0). Children engaged in more sedentary, light, moderate, and vigorous physical activity and had higher counts per minute during weekdays compared to weekend days. There were no sex differences in moderate to vigorous physical activity (87.6 ± 22.4 vs. 93.5 ± 20.6 min and 53.6 ± 21.3 vs. 59.4 ± 22.0 min) during weekday and weekend days. Data indicated that 96% of the girls and 92% of the boys met the international physical activity guideline for children of 60 minutes of MVPA, on weekdays.     

Development of a function to recognize angry facial expressions in 5- to 11-year-old children

In 5- to 6-, 7- to 8-, and 10- to 11-year-old children, age-related features of the effects of former experience on the recognition of emotional facial expressions were found using a cognitive set model. In five- to six-year-old children, an inert set to an angry facial expression was formed and expressed during testing as a large number of erroneous recognition of facial expressions of the perseverative type (assimilative) illusions. Set plasticity was increased in seven- to eight-year-old children and the number of assimilative illusions decreased. In 10- to 11-year-old children, the cognitive set was similar to adults in terms of its plasticity and a ratio of assimilative and contrast illusions. Changes in the spatial synchronization of electrical potentials in the ??- and ??-frequency bands were observed in all age groups, mainly during set formation. In all age groups, we observed a correlation between the bioelectrical data and the effects of former experience on the recognition of facial expression. Based on the data on the coherence of the potentials of the ??- and ??-ranges we propose age-related changes in the involvement of the cortico-hippocampal and fronto-thalamic functional systems of integration of brain activity in organizing the sets to emotionally negative facial expressions.     

Movement-related brain potentials in 6- to 7-year-old children]

Spatial distribution and component structure of movement-related brain potentials (MRBP) were studied in 6-7-years-old children. The structure of Bereitschaftspotentials was found to be complex and heterogeneous the latency of P200 component being shorter than that in adults. MRBP recorded contained specific for children late negative wave that had been called postaction negativity, or PAN. The amplitudes of almost all MRBP components in children under study was the highest in the frontal areas. The results obtained may reflect neurophysiological changes associated with motor development.     

Anthropometric parameters and sexual maturation in 12- to 15-year-old Estonian boys

The aims of this study were 1. to fix main sexual maturation signs and anthropometric measurements, and 2. to investigate relations between maturational status and main anthropometric parameters (i.e. skinfolds, girths, lengths, breadths/lengths) in 12-15-year old boys. In total, 361 boys from Tartu, Estonia, were studied. Body height and weight, 9 skinfolds, 13 girths, 8 lengths and 8 breadths/lengths were measured. Pubertal stages were determined according to the criteria described by Tanner (1962). Self-assessment of pubic hair (PH1-PH5) was used. Genital development (G1-G5) was estimated by palpating the left testis and matching the size of wood ovoid of the Prader orchidometer. Finally, boys were asked about oigarche (= age at the first ejaculation of sperm). Most of the measured anthropometric variables were significantly different in boys of different chronological age and sexual maturity groups. By linear discriminant analysis, the safety of separation of the chronological age groups was higher than by sexual maturation variables. Nonlinear discriminant analysis allowed to separate sexual maturity groups by anthropometric variables up to 99% security. It was concluded that though the growth and development of a child is highly individual, on an average the anthropometric characteristics alter very constantly with the increase of age and biological maturation. Our results indicated that there were some significant differences in the anthropometrical parameters depending on the chronological age and biological maturation. Mostly length and breadth/length parameters change during the studied age period in respect to sexual development subgroups of boys. The skinfold thicknesses were not changed or even decreased.     

Prevalence of overweight and obesity in 2- to 6-year-old Italian children

Objective: To assess the prevalence of overweight and obesity in 2‐ to 6‐year‐old Italian children and to compare the prevalence between the north and the south of the country. Research Methods and Procedures: This was a cross‐sectional study of 2150 subjects (M/F: 1137/1013), 5.36 ± 0.83 years of age. The sampling areas were Verona (north Italy) and Messina (south Italy). We used definitions of overweight and obesity using BMI values, with cut‐off values proposed by the International Obesity Task Force. Results: The prevalence of overweight was 16.6% (males: 13.9%, females: 19.6%), and it was higher in the south (males: 17.8%, females: 22.4%) than in the north (males: 11.3%, females: 17.9%). The prevalence of obesity was 8.0% (males: 8.3%, females: 7.7%), and it was higher in the south (males: 12.3%, females: 10.7%) than in the north (males: 5.7%, females: 5.8%). Using the Centers for Disease Control reference charts, the prevalence of overweight and obesity of Italian children was close to that reported in children living in the United States (32% vs. 32.7%, respectively). Discussion: The prevalence of overweight and obesity in young Italian children is very high, and it is rapidly growing. In the south of the country, the prevalence is higher than in the north.     

Pedometer-determined physical activity among obese and non-obese 8- to 12-year-old Saudi schoolboys

Physical activity levels were measured in obese and non-obese 8- to 12- year-old schoolboys (n=296). Anthropometric measures included weight, height, body mass index (BMI), triceps and subscapular skinfolds, predicted fat percentage, fat mass (FM), fat-free mass (FFM), FM index (FMI), and FFM index (FFMI). Physical activity was assessed using an electronic pedometer for three continuous weekdays. Boys were divided into active and inactive groups based on daily accumulation of pedometer counts above or below 13,000 steps. Obesity was defined as body fat content that equals or exceeds 25% of body weight. The international age- and gender-specific child BMI cut-off points were also used to define overweight and obesity. Estimated fat content for the whole sample averaged 23.3+/-9.7%. More than 37% of the boys were classified as obese. The mean step counts were about 13,489+/-5,791 steps per day (range: 335-29,169 steps). Over 71% of the boys accumulated 10,000 steps or more per day. Based on BMI standards, mean step counts for the obese group (10,602+/-4,800 steps/day) were significantly (p=0.004) lower than in the normal group (14,271+/-5,576 steps/day). Based on fat percentage, obese boys also accumulated significantly (p=0.009) lower numbers of steps per day (12,682+/-5,236) than did non-obese boys (14,915+/-5,643). Further, there were significant differences (p<0.05) between active and inactive boys in weight, BMI, triceps and subscapular skinfolds, fat percentage, FMI, and flexibility. It is concluded that the prevalence of obesity and inactivity among Saudi boys aged 8-12 years was high. Active boys exhibited significantly lower body fat percentage and BMI than inactive peers. Obese boys, on the other hand, were significantly less active than non-obese boys. Increased prevalence of obesity and physical inactivity among Saudi children is a major public health concern.     

Genetic and environmental contributions to prosocial behaviour in 2- to 9-year-old South Korean twins

Although over 50 twin and adoption studies have been performed on the genetic architecture of antisocial behaviour, far fewer studies have investigated prosocial behaviour, and none have done so on a non-western population. The present study examined mothers' ratings of prosocial behaviour in 514 pairs of 2- to 9-year-old South Korean monozygotic and dizygotic twins. Correlational analyses showed a tendency of increasing genetic effects and decreasing shared environmental effects with age although shared family environment effects and the moderating effects of age did not attain statistical significance in model-fitting analyses. The best-fitting model indicated that 55% (95% CI: 45-64%) of the variance in the 2- to 9-year-olds' prosocial behaviour was due to genetic factors and 45% (95% CI: 36-55%) was due to non-shared environmental factors. It is concluded that genetic and environmental influences on prosocial behaviour in young South Koreans are mostly similar to those in western samples.     

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.