Somatotype in 6-11-year-old Italian and Estonian schoolchildren

The study of somatotypes can contribute to the understanding of variability in human body build. The aim of this study was to compare the somatotypes of Italian and Estonian schoolchildren in order to evaluate factors that might lead to variability in somatotypes. The sample consisted of 762 Italian and 366 Estonian children aged 6-11 years. They were somatotyped by the Heath-Carter anthropometric method. Data on organised extra-curricular physical activity and hours of weekly training were also collected. One-way ANOVA was used to evaluate country-related variations of somatotype in each age/sex group, while factorial ANOVA was used to test the influence of country and organised physical activity on the variability of the anthropometric characteristics and somatotype components.There are significant differences in mean somatotypes between the Italian and Estonian children in many age classes and a different constitutional trend in children from the two different countries is observed. The Italian children are more endomorphic and less mesomorphic and ectomorphic than the Estonian children. On the other hand, it emerges from factorial ANOVA, that the somatotype components do not present significant variations related to organised physical activity and to the interaction between the country of origin and sport practice. Moreover, the results of the forward stepwise discriminant analyses show that mesomorphy is the best discriminator between the two countries, followed by ectomorphy.Our findings suggest that the observed differences between Italian and Estonian children could be related mainly to country rather than to the practice of organised physical activity in the two countries.     

Autonomic control of the respiratory-hemodynamic system in 8-to 11-year-old children with different baroreflex sensitivities

The efficiency of baroreflex control depends on the baroreflex sensitivity (BRS), which is defined as the ratio of the change in the heart rate (HR) to the change in the blood pressure (BP). The BRS value may be used for assessing the autonomic control of the cardiovascular system and the degree of autonomic dysfunction. Until recently, the baroreflex had not been assessed in a large population of healthy subjects. In this study, the BRS was estimated by the ratio of the low-frequency component of the HR spectrum and the low-frequency component of the rhythm of the systolic BP. For assessing the arterial baroreflex in children, the BRSs for spontaneous and induced baroreflexes were compared. Sex-and age-related differences in BRS were found in 8-to-11-year-old children, and correlations between BRS and some spectral components of HR variability (HRV) and BP rhythm variability were determined. Cluster analysis of the BRS calculated for the spontaneous baroreflex at rest was used to distinguish three clusters of subjects (with high, medium, and low BRSs). These clusters differed in the variability of the basic parameter and size and showed sex-related differences.     

Predicting anaerobic capabilities in 11-13-year-old boys

Anaerobic exercise is involved in many recreational and competitive sport activities. This study first established regression equations to predict maximal anaerobic power and then cross-validated these prediction equations. Using stepwise multiple regression analysis prediction equations for relative (watts per kilogram of body mass) and absolute (watts) mean and peak anaerobic power using the 30-second Wingate Test as the power measure were determined for 40 boys (age, 11-13 years). Percentage of body fat, free-fat weight, midthigh circumference, and 30-m dash were the independent predictive variables with the generated regression equations subsequently cross-validated using 20 different boys (age, 11-13 years). Significant correlations (Pearson r) were found for the cross-validation subjects between the measured power outputs and predicted power outputs for relative mean power (r = 0.48, p < 0.05), absolute mean power (r = 0.77, p < 0.01), and absolute peak power (r = 0.76, p < 0.01). Using paired t-tests, no significant mean differences (p > 0.05) were found for the same subjects between actual and predicted power outputs for relative mean power, absolute mean power, and absolute peak power. Prediction of maximal anaerobic power from selected anthropometric measurements and 30-m dash appears tenable in 11-13-year-old boys and can be accomplished in a simple cost- and time-effective manner.     

Correlation of the characteristics of EEG potentials with the indices of attention in 12-to 13-year-old children

We studied correlations of the spectral characteristics of EEG with the indices characterizing the level of attention in 60 children (12 to 13 years old). Indices of voluntary attention were measured using a complex of psychological tests, including a Bourdon’s test (correcture test), a two-stimulus go/no-go test, a computer test (a modification of the Bourdon’s test for characterization of concentration and stability of attention), and Schulte’s tables. Children manifesting a good working ability (corresponding to the results of the go/no-go test and correcture test) showed relatively high values of the ratio of spectral powers (SPs) of the beta 1 and theta rhythms. These ratios were greater in the right hemisphere; this is probably indicative of a greater contribution of neuronal mechanisms of this hemisphere to providing watchfulness and stability of attention. Children demonstrating increased impulsivity (according to the results of the go/no-go test) were characterized by low modal frequencies of the alpha rhythm in the occipital brain regions, while children with relatively high values of this frequency in various cerebral regions demonstrated high indices of attentiveness and rates of the cognitive processes. Children performing the test task with especially high accuracy were characterized by high ratios of SPs of the low-frequency beta rhythm vs theta rhythm (mostly in the central and parietal regions of both hemispheres). The approach we have applied can be used for measuring the objective indices characterizing the state of the attention sphere in children. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 248–256, May–June, 2006.     

Secular trends in the prevalence of overweight and obesity in Sicilian schoolchildren aged 11-13 years during the last decade

The present study evaluates trends in the prevalence of overweight and obesity in relation to gender and area of residence between two cohorts of students aged 11–13 years in Sicily. The analysis was performed on 1,839 schoolchildren, with 924 and 915 children being studied in 1999–2001 and 2009–2010, respectively. The children who were enrolled during 2009–2010 had significantly higher body mass indexes (BMI), BMI z-scores, and waist circumferences than the children who were studied during 1999–2001 (p<0.0001 for all); these differences was also observed when the cohort was subdivided according to gender or residence area The prevalence of obesity increased significantly from 7.9% in 1999–2001 to 13.7% in 2009–2010 (p<0.0001), whereas thinness decreased significantly from 10.1% to 2.3% (p<0.0001) in the same periods. The increase of trends in the prevalence of obesity was significantly higher in males (9.7% vs. 17.6%, p = 0.0006) than in females (6.3% vs. 9.8%, p = 0.04) and was slightly higher in urban areas (8.8% vs. 14.3%, p = 0.002) than in rural areas (7.8% vs. 13.0%, p = 0.012). The male gender was associated with a higher risk of being overweight or obese (odds ratio: 1.63; 95% confidence intervals: 1.24–2.15; p = 0.0005) in 2009–2010 than in 1999–2001, after adjusting for age and the residence area. In conclusion, this study showed an increasing trend in the prevalence of overweight and obesity in Sicilian schoolchildren during the last decade and that this trend was related to gender, age and the area of residence. More specifically, our data indicated that the prevalence of obesity increased by 5.8%, the prevalence of thinness decreased by 7.8% and the prevalence of normal-weight children did not change over the course of a decade. These results suggest a shift in the body weights of Sicilian children toward the upper percentiles.     

Energy supply for muscle activity in 13- to 14-year-old boys depending on the rate of puberty

The energy supply for muscle activity in healthy boys aged 13–14 years (n = 162) at various puberty stages (PSs) has been studied using functional and ergometric working capacity indices. It has been established that boys at PSs II–IV significantly differ in the indices of power, capacity, and efficiency of bioenergy systems. Three groups of bioenergy indices have been distinguished that differ in the direction of variations in adolescents depending on the rate of puberty. The first group includes the physiological variables the highest levels of which are observed in adolescents with high rates of development. All these indices belong to the anaerobic alactic and anaerobic glycolytic components of physical capability. The second group includes the physiological variables the highest levels of which are observed in adolescents with medium rates of development; the lowest levels, in adolescents with accelerated rates of development. These indices mainly reflect the set of aerobic capacities. The third group includes the physiological variables the highest levels of which are observed in adolescents with low rates of development and the lowest levels, in boys with accelerated rates of maturation. These indices reflect the maximal aerobic power and endurance. It was found that adolescents aged 13–14 years with moderate rates of development are characterized by higher indices of power and capacity of the aerobic energy supply system as compared to adolescents with accelerated maturation. This group of adolescents has also been observed to exhibit a lower maximal aerobic power against a background of higher capacity and efficiency of the aerobic system functioning as compared to adolescents with slow maturation. Adolescents with moderate rates of maturation have been shown to surpass schoolboys with accelerated or slow development with respect to the power of mixed aerobic-anaerobic work. Boys aged 13–14 years with accelerated development have been found to differ from schoolboys with moderate or slow maturation by high anaerobic capacity, relatively low aerobic capacities and an increase in the tone of the parasympathetic nervous system. This should be taken into consideration in terms of a differentiated approach to the formation of load during physical education and athletic training of adolescents aged 13–14 years.     

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.     

The psychophysiological cost of intense information load in 5-to 14-year-old children and adolescents

The psychophysiological cost of activity was determined in 5- to 14-year-old children and adolescents (n = 612) by correlating the performance of intense information load with the value of autonomic shifts in the course of the test. It was shown that the psychophysiological cost of information load in the state of functional comfort (self-determined speed) decreased 2.2- to 5.4-fold in the period from 5–6 to 13–14 years of age and the psychophysiological cost of intense intellectual activity with the maximum speed under the conditions of a time deficit (the maximum speed) decreased 1.2- to 4-fold. The greatest changes in the psychophysiological cost of intense intellectual activity were observed at the beginning of regular schooling and during puberty. The data indicate the need for a continuous search for new, efficient, and more physiologically adequate ways of control of the process of training and education taking into consideration the psychophysiological cost of intense academic activity in different periods of ontogeny and ensuring a beneficial effect of educational technologies on the health and development of schoolchildren.