Antioxidant response and oxidative damage induced by a swimming session: influence of gender

In this study, we examined oxidative stress after a swimming session, the responses of the antioxidant defences, and the influence of gender on these responses. Fifteen boys and eight girls participated voluntarily in the study. Plasma concentrations of 17-beta-estradiol, vitamin E, retinol, carotenes, ascorbate, malondialdehyde, and the carbonyl index were determined. Creatine kinase, gamma glutamyl transpeptidase, and lactate dehydrogenase activities, as well as glucose, urea, urate, cholesterol, and triglycerides, were determined in serum. Plasma concentrations of 17-beta-estradiol were higher in girls than in boys. Exercise increased plasma ascorbate both in boys and in girls. Malondialdehyde increased in boys but was maintained in girls after exercise. Creatine kinase values corrected for lean body mass were similar in boys and girls at baseline, but the post-exercise values in boys were higher than in girls. A positive correlation was observed in boys, but not in girls, between plasma malondialdehyde and creatine kinase corrected concentrations. Furthermore, a negative correlation was observed between the increase in circulating neutrophils and in creatine kinase activity in girls but not in boys. In conclusion, a swimming session induced higher muscular and oxidative damage in boys than in girls.     

Potential mediating pathways through which sports participation relates to reduced risk of suicidal ideation

Suicide ranks as the third leading cause of death for American youth. Researchers examining sport participation and suicidal behavior have regularly found inverse relationships. This study represents the first effort to test a model depicting potential mechanisms through which sport participation relates to reduced risk of suicidal ideation. The participants were 450 undergraduate students. Measures assessed participants' involvement in university-run sports and other activities; frequency of physical activity; and perceived social support, self-esteem, depression, hopelessness, loneliness, and suicidal ideation. Regression analyses confirmed a path model and tested for mediation effects. Vigorous activity mediated relationships between sport participation and self-esteem and depression; and self-esteem and depression mediated the relationship between vigorous activity and suicidal ideation. Social support mediated relationships between sport participation and depression, hopelessness, and loneliness; and each of these risk factors partially mediated the relationship between social support and suicidal ideation. However no variable fully mediated the relationship between sport participation and suicidal ideation. This study provides a foundation for research designed to examine pathways through which sport participation relates to reduced risk of suicidal behavior.     

Munchausen by Proxy in an international context

OBJECTIVE: The professional literature on Munchausen by Proxy (MBP) abuse consists of more than 400 articles, chapters, and books. Most have come from a handful of English-speaking industrialized countries. Our aims were to establish the extent to which published work about MBP has emerged from outside these countries, and to determine the characteristics of any reported cases. METHOD: Numerous health care computer databases were queried, and the results supplemented by materials accumulated less formally. RESULTS: We identified 59 articles from 24 countries describing at least 122 cases in 9 different languages. Among cases in which the information was available, the mother was the sole perpetrator in 86%, the victim was aged between 3 years and 13 years in 52%, and the victim was male in 54%. The presentations of MBP appear to be similar across the world with the exception of induced apnea, which emerged as notably uncommon in this review. An extensive table presents the characteristics of each case. CONCLUSIONS: MBP clearly is not a phenomenon unique to Western or highly medicalized societies. This form of abuse is being increasingly recognized and reported throughout the world. The literature from the US, Canada, UK, Australia, and New Zealand often presupposes access to resources, such as subspecialists and social service agencies, that may be seriously constrained in other countries. The contributions of professionals elsewhere will be vital in ensuring that the efforts in English-speaking industrialized settings to develop standards of care encompass an international perspective.     

Advances in the application of information technology to sport performance

This paper overviews the diverse information technologies that are used to provide athletes with relevant feedback. Examples taken from various sports are used to illustrate selected applications of technology-based feedback. Several feedback systems are discussed, including vision, audition and proprioception. Each technology described here is based on the assumption that feedback would eventually enhance skill acquisition and sport performance and, as such, its usefulness to athletes and coaches in training is critically evaluated.     

Muscle power patterns in the mid-acceleration phase of sprinting

To assess the role of the lower limb joints in generating velocity in the mid-acceleration phase of sprinting, muscle power patterns of the hip, knee and ankle were determined. Six male sprinters with a mean 100 m time of 10.75 s performed repeated maximal sprints along a 35 m indoor track. A complete stride across a force platform, positioned at approximately 14 m into the sprint, was video-recorded for analysis. Smoothed coordinate data were obtained from manual digitization of (50 Hz) video images and were then interpolated to match the sampling rate of the recorded ground reaction force (1000 Hz). The moment at each joint was then calculated using inverse dynamics and multiplied by the angular velocity to determine the muscle power. The results showed a proximal-to-distal timing in the generation of peak extensor power during stance at the hip, the knee and then the ankle, with the plantar flexors producing the greatest peak power. Apart from a moderate power generation peak towards toe-off, knee power was negligible despite a large extensor moment throughout stance. The role of the knee thus appears to be one of maintaining the centre of mass height and enabling the power generated at the hip to be transferred to the ankle.     

Information processing deficits in children with attention-deficit/hyperactivity disorder, inattentive type, and children with reading disability

We examined the information processing capabilities of children diagnosed with the inattentive subtype of attention-deficit/hyperactivity disorder (ADHD) who had been characterized as having a sluggish cognitive tempo. Children referred for school-related problems (n = 81) and nonreferred community controls (n = 149) participated. Of the referred children, 24 met criteria for ADHD, 42 met criteria for reading disability (RD), and 9 of these were comorbid for RD and ADHD. Children with ADHD differed from those without ADHD on a visual search task but not on an auditory processing task; the reverse was true for children with RD. Decomposition of the visual search task into component operations demonstrated that children in the ADHD group had a slow processing rate that was not attributable to inattention. The children with ADHD were not globally poor at information processing or inattentive, but they demonstrated diminished speed of visual processing.     

Sensory, cognitive, and linguistic factors in the early academic performance of elementary school children: The Benton-IU project

Standardized sensory, perceptual, linguistic, intellectual, and cognitive tests were administered to 470 children, approximately 96% of the students entering the first grade in the four elementary schools of Benton County, Indiana, over a 3-year period (1995--1997). The results of 36 tests and subtests administered to entering first graders were well described by a 4-factor solution. These factors and the tests that loaded most heavily on them were reading-related skills (phonological awareness, letter and word identification); visual cognition (visual perceptual abilities, spatial perception, visual memory); verbal cognition (language development, vocabulary, verbal concepts); and speech processing (the ability to understand speech under difficult listening conditions). A cluster analysis identified 9 groups of children, each with a different profile of scores on the 4 factors. Within these groups, the proportion of students with unsatisfactory reading achievement in the first 2 years of elementary school (as reflected in teacher-assigned grades) varied from 3% to 40%. The profiles of factor scores demonstrated the primary influence of the reading-related skills factor on reading achievement and also on other areas of academic performance. The second strongest predictor of reading and mathematics grades was the visual cognition factor, followed by the verbal cognition factor. The speech processing factor was the weakest predictor of academic achievement, accounting for less than 1% of the variance in reading achievement. This project was a collaborative effort of the Benton Community School Corporation and a multidisciplinary group of investigators from Indiana University.     

Indexing response to intervention: a longitudinal study of reading risk from kindergarten through third grade

In this study, response to intervention and stability of reading performance of 41 kindergarten children identified as at risk of reading difficulty were evaluated from kindergarten through third grade. All students were assessed in the fall of each academic year to evaluate need for intervention, and students who fell below the 30th percentile on criterion measures received small-group supplemental intervention. Measures included a combination of commercial normative referenced measures and specific skill and construct measures to assess growth or change in reading risk status relative to 30th percentile benchmarks. Results indicated that consistent with the findings of prior research involving students with comparable entry-level performance, the majority of children identified as at risk in the beginning of kindergarten responded early and positively to intervention. On average, absolute performance levels at the end of kindergarten positioned students for trajectories of later reading performance that exceeded the 50th percentile on the majority of measures. Moreover, changes in risk status that occurred early were generally sustained over time. Only oral reading fluency performance failed to exceed the 30th percentile for the majority of students.