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Purpose: The purpose of this study was to examine divided attention over a large age range by looking at the effects of 3 nonspeech tasks on concurrent speech motor performance. The nonspeech tasks were designed to facilitate measurement of bidirectional interference, allowing examination of their sensitivity to speech activity. A cross-sectional design was selected to explore possible changes in divided-attention effects associated with age. Method: Sixty healthy participants were separated into 3 groups of 20: younger (20s), middle-aged (40s), and older (60s) adults. Each participant completed a speech task (sentence repetitions) once in isolation and once concurrently with each of 3 nonspeech tasks: a semantic decision linguistic task, a quantitative-comparison cognitive task, and a manual motor task. The nonspeech tasks were also performed in isolation. Results: Data from speech kinematics and nonspeech task performance indicated significant task-specific divided attention interference, with divided attention affecting speech and nonspeech measures in the linguistic and cognitive conditions and affecting speech measures in the manual motor condition. There was also a significant age effect for utterance duration. Conclusions: The results increase what is known about bidirectional interference between speech and other concurrent tasks as well as age effects on speech motor control., Speech is a highly sophisticated feat of fine motor performance. However, research has shown that speech production can be affected in subtle but measureable ways by the concurrent performance of [...]

Purpose: This study compared pragmatic language in youths (9-17 years) with autism spectrum disorder (ASD) and those with typical development (TD) on the Yale in vivo Pragmatic Protocol (YiPP), a semistructured, dynamic conversational assessment. Method: Participants (n = 118) were divided into groups based on age and diagnosis. Each completed the YiPP, which included 4 pragmatic domains (discourse management, communicative functions, conversational repair, presupposition). The participant's response to each probe was scored correct or incorrect; incorrect scores elicited cues from the examiner, and level of cue required for a correction was also scored. Results: The YiPP showed high reliability and internal consistency, with moderate concurrent validity, sensitivity, and specificity. The group with ASD performed worse overall on YiPP probes compared to their TD counterparts on both error (d = 0.96) and cue (d = 0.91) scores. Item analyses revealed greater gaps between older students with ASD and their TD peers than between the 2 younger groups. Conclusions: These data suggest that a probe measure designed to assess pragmatic abilities in children with ASD within a conversational context has some validity for contributing to diagnostic classification and can identify specific areas of pragmatic vulnerabilities as part of a clinical assessment., A core feature, and one of the primary diagnostic symptoms, of autism spectrum disorder (ASD) is a qualitative impairment in communication (American Psychiatric Association, 2000). Current estimates suggest that a [...]

Abstract This study aimed to quantify articulation rate among Hebrew speaking children and adolescents across a wide age range, and to assess whether age-related differences vary according to metric. One [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2010.07.002 Byline: Michael Chaiton, Joanna Cohen, Jennifer O'Loughlin, Juergen Rehm Keywords: Smoking; Depressive symptoms; Adolescents; Longitudinal; Self-medication Abstract: Smoking to alleviate negative affect or improve physiological functioning (i.e., self-medication) is one explanation for the association between depression and smoking in adolescents. This study tests whether using cigarettes to improve mood or physiological functioning is associated with the onset, and change over time, of elevated depressive symptoms. Data were drawn from the Nicotine Dependence in Teens study which followed 1293 participants initially aged 12-13years in Montreal, Canada every three months for five years. The subsample included 662 adolescents who had been current smokers (reported smoking during the previous three months) at any point during the study. Survival analysis was used to test whether self-medication scores predicted onset of elevated depressive symptoms. Changes over time in depressive symptom scores relative to self-medication scores were modeled in growth curve analyses controlling for sex and number of cigarettes smoked per week. Smokers who reported higher self-medication scores had higher depressive symptom scores. The interaction between self-medication scores and the acceleration rate in depressive symptom scores was significant and negative, suggesting that participants with higher self-medication scores had decelerated rates of change in depression over time compared to participants with lower self-medication scores. Smoking appears to be ineffective at reducing depressive symptoms. These findings are consistent with a version of the Positive Resource Model that suggests that smoking will not lower depressive symptoms, but could slow the rate of change over time. Alternatively, the perceived positive benefits may be the result of alleviation of symptoms of withdrawal and craving resulting from abstinence. The self-medication scale may identify a population at risk of increased levels of depressive symptoms.

The aim of this study was to examine acute physiological responses and time-motion characteristics associated with 4 soccer-specific small-sided game (SSG) formats (3 vs. 4 players, 3 vs. 3 players + floater, 5 vs. 6 players, and 5 vs. 5 players + floater) and 4 rule changes in elite youth soccer players. Sixteen male youth soccer players (mean [+ or -] SD: age = 15.6 [+ or -] 0.8 years, stature = 170.8 [+ or -] 6.6 cm, body mass = 67.5 [+ or -] 6.2 kg, and 20-m shuttle run estimated [[??]O.sub.2]max = 57.4 [+ or -] 3.7 ml x [kg.sup.-1] x [min.sup.-1]) participated in the study, in which heart rate (HR), rating of perceived exertion (RPE), blood lactate ([La.sup.-]), and time-motion characteristics were recorded. The rule change requiring extra sprint running had a greater effect on the time-motion characteristics than all other rule modifications but no effect on acute %HRmax, [La.sup.-], and RPE. Rule changes had no effect on RPE. Fixed underload teams (i.e., lower number of players compared with the opponent team) recorded a significantly higher RPE compared with the fixed overload teams, although there were no differences in %HRmax and [La.sup.-]. The major practical findings are that subtle changes in SSGs playing rules can influence the physiological, perceptual, and time-motion responses in young elite soccer players. Rules that are related to a team's chances of scoring may improve player motivation and thereby increase training intensity during SSGs. There were no differences between fixed and variable formats in terms of physiological and perceptual responses, although both may provide useful technical-tactical training. Coaches should take care in designing different soccer SSGs as each rule or game format change may influence exercise intensity independently. KEY WORDS overload, game format, rule modifications, sprints

The purpose of the present study was to examine the association among different measures of lower body muscular strength in children, and the association between measures of lower- and upper-body muscular strength. The study population comprises 94 (45 girls) healthy Caucasian children aged 6-17 years. Children performed several lower body explosive muscular strength tests (i.e., standing long jump [SLJ], vertical jump, squat jump, and countermovement jump) and upper body muscular strength tests (i.e., throw basketball, push-ups, and isometric strength exercises). The association among the study tests was analyzed by multiple regression. The SU was strongly associated with other lower body muscular strength tests ([R.sup.2] = 0.829-0.864), and with upper body muscular strength tests ([R.sup.2] = 0.694-0.851). The SLJ test might be therefore considered a general index of muscular fitness in youth. The SLJ test is practical, time efficient, and low in cost and equipment requirements. KEY WORDS fitness, field tests, children, adolescents

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apergo.2009.02.006 Byline: Thomas R. Waters (a), Arun Garg (b) Abstract: Youth and adolescents are routinely engaged in manual material handling (MMH) tasks that may exceed their strength capability to perform the task and may place them at excessive risk for musculoskeletal disorders. This paper reports on a two-dimensional biomechanical model that was developed to assess MMH tasks performed by youth 3-21 years of age. The model uses age, gender, posture of the youth performing the MMH activity, and weight of the load handled as input, and provides an estimate of the strength demands of the task and spinal disc compression and shear force resulting from the activity as output. The model can be used to assess whether a specific MMH task exceeds the strength demands for youth of certain ages or genders, which of the internal muscle strengths are most affected, and provides information about the estimated spinal disc compression and shear forces on the spine as a result of the specified MMH task. These results would be helpful in deciding whether a task is appropriate for a youth to perform or whether a certain task modification may be sufficient in reducing the physical demands to a level acceptable for a youth of certain age and gender. Author Affiliation: (a) National Institute for Occupational Safety and Health, Division of Applied Research and Technology, 4676 Columbia Parkway, 45226 Cincinnati, OH, USA (b) University of Wisconsin-Milwaukee, P.O. Box 413, 2200 E. Kenwood Blvd., Milwaukee, WI 53201-0413, USA Article History: Received 18 September 2008; Accepted 24 February 2009 Article Note: (footnote) [star] The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

The purpose of the study was to investigate the acute effect of different warm-up protocols on anaerobic performance in elite youth soccer players. Twenty elite youth soccer players (mean age 17.2 [+ or -] 1.2 years) performed 3 different warm-up protocols in a random order on nonconsecutive days. Each warm-up protocol consisted of a 5-minute low-intensity jog followed by 10 minutes of static stretching (SS), dynamic stretching (DS), or dynamic stretching followed by 8 front squats + 20% body mass (DSR). Subjects performed a counter-movement jump followed by a 10- and 20-m sprint test immediately and at 3 and 6 minutes after each warm-up protocol. Vertical jump performance following DSR was better at 3 and 6 minutes than after DS, which in turn was better than after SS at 0, 3, and 6 minutes (p < 0.05). Jump performance was better at 3 minutes than immediately after, and this improvement was maintained at 6 minutes after DSR (p < 0.05). A better sprint performance was observed after DSR and DS compared with SS immediately and at 3 and 6 minutes following each warm-up protocol (p < 0.05). The results of the study suggest that a dynamic warm-up with the inclusion of resistance enhances jumping ability more than dynamic exercise alone. In addition, a dynamic warm-up produces a superior sprint and jump performance compared to a warm-up consisting of static stretching. KEY WORDS youth, soccer, warm-up, stretching, power, potentiation

Manual resistance training (MRT), an alternative to traditional resistance training, requires minimal equipment and may be effective when applied in school-based physical education (PE) classes. The purpose of this study was to document the physical changes in adolescents (n = 222) using MRT in school-based PE settings. Six fitness tests from the Fitness-gram assessment tool were selected to assess students' cardiovascular and muscular fitness, and skinfold tests were used to assess body composition. One control and 2 experimental groups were defined. The control group of students (n = 129) attended regular PE classes. One experimental group (n = 63) attended PE that was complemented by the MRT system. A second experimental group (n = 30) attended PE complemented by MRT and cardiovascular endurance training. With use of the selected Fitnessgram tests, post-test measurements were performed after 9 and 18 weeks of PE. At baseline, there were no significant differences among the 3 groups for most measures. Compared with baseline, the experimental groups improved significantly in all 6 fitness measures and showed more improvements than the control group in most fitness measures both at 9 and 18 weeks. None of the groups showed significant improvement in body composition. The results documented that an MRT-complemented PE program was effective in improving adolescents' muscular fitness. An 18-week combined MRT and cardiovascular endurance training program effectively improved cardiovascular and muscular fitness but was ineffective in improving adolescent body composition. An MRT-based exercise session requires minimal equipment and set-up and can be performed in a short period of time, and therefore it is suitable for application in regular PE settings. KEY WORDS strength training, youth fitness, adolescent fitness, resistance training modalities, school resistance training

This study has sought to determine if the Tommie Smith Youth Athletic Initiative (TSYAI) intervention could decrease the risk factors for childhood obesity among children 5 to 10 years of age. The TSYAI intervention is a 14-week after-school intervention for students in Grades K-5 that was started during the spring of 2008. It serves 63 children in a predominantly African American elementary school. The intervention consists of supervised after-school sessions 3 days per week. These sessions include 2 days of physical activity (flexibility, resistance, and track-and-field training) and 1 day of 45 min of nutrition education modules based on the Transtheoretical Model of behavior change followed by 45 min of group physical activity. Ninety-two percent of the participants are African American and 60% are overweight or obese (>85th percentile BMI for age and gender). The findings indicate that the TSYAI intervention significantly improves the participant's cardiovascular fitness, body composition, and dietary habits. Keywords: exercise; pediatrics; diet and eating

Current recommendations suggest that school-aged youth should participate daily in 60 minutes or more of moderate to vigorous physical activity that is developmentally appropriate and enjoyable and involves a variety of activities (219). Not only is regular physical activity essential for normal growth and development, but also a physically active lifestyle during the pediatric years may help to reduce the risk of developing some chronic diseases later in life (196). In addition to aerobic activities such as swimming and bicycling, research increasingly indicates that resistance training can offer unique benefits for children and adolescents when appropriately prescribed and supervised (28,66,111,139,147,234). The qualified acceptance of youth resistance training by medical, fitness, and sport organizations is becoming universal (5,6,8,12,18,33,104,167,192,215). Nowadays, comprehensive school-based programs are specifically designed to enhance health-related components of physical fitness, which include muscular strength (169). In addition, the health club and sport conditioning industry is getting more involved in the youth fitness market. In the U.S.A., the number of health club members between the ages of 6 and 17 years continues to increase (127,252) and a growing number of private sport conditioning centers now cater to young athletes. Thus, as more children and adolescents resistance train in schools, health clubs, and sport training centers, it is imperative to determine safe, effective, and enjoyable practices by which resistance training can improve the health, fitness, and sports performance of younger populations. The National Strength and Conditioning Association (NSCA) recognizes and supports the premise that many of the benefits associated with adult resistance training programs are attainable by children and adolescents who follow age-specific resistance training guidelines. The NSCA published the first position statement paper on youth resistance training in 1985 (170) and revised this statement in 1996 (72). The purpose of the present report is to update and clarify the 1996 recommendations on 4 major areas of importance. These topics include (a) the potential risks and concerns associated with youth resistance training, (b) the potential health and fitness benefits of youth resistance training, (c) the types and amount of resistance training needed by healthy children and adolescents, and (d) program design considerations for optimizing long-term training adaptations. The NSCA based this position statement paper on a comprehensive analysis of the pertinent scientific evidence regarding the anatomical, physiological, and psychosocial effects of youth resistance training. An expert panel of exercise scientists, physicians, and health/physical education teachers with clinical, practical, and research expertise regarding issues related to pediatric exercise science, sports medicine, and resistance training contributed to this statement. The NSCA Research Committee reviewed this report before the formal endorsement by the NSCA. For the purpose of this article, the term children refers to boys and girls who have not yet developed secondary sex characteristics (approximately up to the age of 11 years in girls and 13 years in boys; Tanner stages 1 and 2 of sexual maturation). This period of development is referred to as preadolescence. The term adolescence refers to a period between childhood and adulthood and includes girls aged 12-18 years and boys aged 14-1 8 years (Tanner stages 3 and 4 of sexual maturation). The terms youth and young athletes are broadly defined in this report to include both children and adolescents. By definition, the term resistance training refers to a specialized method of conditioning, which involves the progressive use of a wide range of resistive loads and a variety of training modalities designed to enhance health, fitness, and sports performance. Although the term resistance training, strength training, and weight training are sometimes used synonymously, the term resistance training encompasses a broader range of training modalities and a wider variety of training goals. The term weightlifting refers to a competitive sport that involves the performance of the snatch and clean and jerk lifts. This article builds on previous recommendations from the NSCA and should serve as the prevailing statement regarding youth resistance training. It is the current position of the NSCA that: 1. A properly designed and supervised resistance training program is relatively safe for youth. 2. A properly designed and supervised resistance training program can enhance the muscular strength and power of youth. 3. A properly designed and supervised resistance training program can improve the cardiovascular risk profile of youth. 4. A properly designed and supervised resistance training program can improve motor skill performance and may contribute to enhanced sports performance of youth. 5. A properly designed and supervised resistance training program can increase a young athlete's resistance to sports-related injuries. 6. A properly designed and supervised resistance training program can help improve the psychosocial well being of youth. 7. A properly designed and supervised resistance training program can help promote and develop exercise habits during childhood and adolescence. KEY WORDS strength training, weight training, weightlifting, children, adolescents

The objectives of the study were to evaluate the reproducibility of the maximal isometric trunk muscle strength testing and inclinometric method to measure body sway and to establish reference values for these measurements in young Finnish adults. Reproducibility was assessed with 2 repeated measurements. Reference values are based on the cross-sectional cohort data. Maximal isometric trunk extension, flexion, and rotations were measured in standing posture. Body sway was measured with inclinometric method. The subjects (N = 874) belonged to a subcohort of the Northern Finland Birth Cohort 1986. Intrarater reliability was assessed with 19 volunteers from the birth cohort, and interrater reliability was assessed with 15 young healthy adults. Intrarater reliability intraclass correlation coefficients (ICCs) for body sway measurements ranged from 0.39 to 0.74 and for trunk muscle strength measurements from 0.84 to 0.94. Interrater reliability ICC for body sway ranged from 0.61 to 0.85 and for trunk muscle strength from 0.84 to 0.88. Maximal muscle strength was better in men than in women, but extensor to flexor ratio was higher in women. Women had significantly better values in all body sway measurements than men. Our study showed a remarkable biological variation in isometric trunk muscle strength and inclinometric body sway. Although ICC analysis indicated good reliability, the Bland and Altman analysis revealed quite wide range of measurement error. However, reproducibility of isometric trunk muscle testing is comparable to other measurements of trunk muscle function in use. Reference values collected in our study offer valuable normative data for future studies and can be used as a tool when assessing physical capacity of healthy subjects or patients with different pathological conditions. KEY WORDS lumbar strength, postural balance, reliability of results

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ahj.2009.04.021 Byline: Hideo Ohuchi (a), Yoshihiro Miyamoto (b), Masaki Yamamoto (a), Haruko Ishihara (a), Hidemi Takata (a), Aya Miyazaki (a), Osamu Yamada (a), Toshikatsu Yagihara (c) Abstract: Abnormal glucose metabolism (AGM) adversely impacts morbidity and mortality in patients with chronic heart failure. No data on AGM in adult patients with congenital heart disease (ACHD) are available. Author Affiliation: (a) Department of Pediatrics, National Cardiovascular Center, Osaka, Japan (b) Department of Atherosclerosis and Diabetes, National Cardiovascular Center, Osaka, Japan (c) Department of Thoracic Surgery, National Cardiovascular Center, Osaka, Japan Article History: Received 18 December 2008; Accepted 2 April 2009

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-8624.2008.01220.x Byline: Marielle D. Beijersbergen (1), Marian J. Bakermans-Kranenburg (1), Marinus H. van IJzendoorn (1), Femmie Juffer (1) Abstract: The current study examined whether adolescents' attachment representations were associated with differences in emotion regulation during the Adult Attachment Interview (AAI; C. George, N. Kaplan, & M. Main, 1996) and during a mother-adolescent conflict interaction task (Family Interaction Task [FIT]; J. P. Allen et al., 2003). Participants were one hundred and fifty-six 14-year-old adolescents. Dismissing adolescents showed less interbeat interval (IBI) reactivity (indicating less stress) during the AAI than secure adolescents. However, during the FIT, dismissing adolescents showed more IBI reactivity. No differences in physiological reactivity were found between individuals with resolved or unresolved loss or trauma during the AAI or FIT. The results indicate that dismissing adolescents may effectively use a defensive strategy during the AAI but less so in direct conflict interaction with their attachment figure. Author Affiliation: (1)Leiden University Article note: Correspondence concerning this article should be addressed to Marian J. Bakermans-Kranenburg, Centre for Child and Family Studies, Leiden University, P.O. Box 9555, 2300 RB Leiden, The Netherlands. Electronic mail may be sent to bakermans@fsw.leidenuniv.nl.

While the segmentation of residential areas by race is well known to affect the social and economic well-being of the segregated minority group in the United States, the relationship between segregation and health has received less attention. This study examines the association between racial residential segregation, as measured by the isolation index, and individual weight status in US metropolitan areas. Multi-level, nationally representative data are used to consider the central hypothesis that segregation is positively associated with weight status among African Americans, a group that is hyper-segregated and disproportionately affected by unhealthy weight outcomes. Results show that among non-Hispanic blacks, higher racial isolation is positively associated with both a higher body mass index (BMI) and greater odds of being overweight, adjusting for multiple covariates, including measures of individual socioeconomic status. An increase of one standard deviation in the isolation index is associated with a 0.423 unit increase in BMI (p Keywords: Racial segregation; Obesity; Body mass index; Socioeconomic factors; Contextual analysis; Health inequalities; USA

The purpose of this study, in which 113 talented youth soccer players (M = 16.0 yr., SD = 1.5), selected by their age and level of performance participated, was to investigate interval endurance capacity needed to play at the highest level of competition in the age-category 12 through 18. Multivariate analyses of covariance with factors of level of performance and age category showed that players ages 16 through 18 years outscored the players ages 12 through 15 years on the interval endurance capacity (p.05). In conclusion, development of the interval endurance capacity seems crucial for a talented youth soccer player to be successful.

The rise in numbers of overweight/obese children in the W K is causing widespread concern. Biomedical constructions of body acceptability and 'good health' mean that overweight/obese young people are frequently seen as deviant. The socio-cultural contexts within which young teenagers become fat, and lay conceptualisations of fatness, have largely been ignored. This qualitative study involved in-depth interviews with teenagers aged 13-14 years (n = 36), drawn from families living in areas classified as socio-economically disadvantaged. Half of the sample had a Body Mass Index (BMI) classifying them its overweight or obese, whilst the remainder were classified as being 'normal' weight. Participants' embodied perceptions of fatness were complex and sometimes contradictory. We discuss what young teenagers perceive the influences on fatness and body size to be; the professed consequences of being fat; participants' experiences of attempting to lose weight; and, their reported interactions with friends and family relating to fatness and dieting. Participants rarely mentioned ally health-related consequences of their own and others' fatness, although wearing 'nice' clothes and being slowed down were raised as considerations by girls and boys, respectively. 'Normal' weight teenagers who disliked their bodies or who wanted to Jose weight often claimed to be anxious about this. Being very obese also led to anxiety and reported attempts at 'crash dieting'. Acceptance of body size/shape was, however, common amongst the overweight and obese teenagers, although some had attempted weight loss. The teenagers in this study were rarely supportive of friends or family who attempted to lose weight and frequently disagreed with others' perceptions of fatness. These findings are important as they contradict the common perception that being overweight/ obese is related to body dissatisfaction and that young people have a fear of fatness. Keywords: Scotland; Young teenagers: Obesity; Overweight; Body image; Qualitative study

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apergo.2005.01.012 Byline: Bing-Shiang Yang, James A. Ashton-Miller Abstract: A fall from a stepladder is often initiated by a loss of lateral stability. An inverted pendulum model of the human, validated by experiment, was used to determine the feasible range of whole-body center of mass (COM) states for which weight can be transferred laterally on a ladder tread without a ladder rail losing contact with the ground ('no lift-off' stability region). The results show that the size of the feasible no lift-off region was inversely proportional to the height of the tread above the ground, the distance of the stance foot from the ipsilateral rail, and lateral ground inclination angle. For given initial COM kinematics on a tread height equal to 40% human body height, a stance-foot location equal to one-eighth tread width and a 3.5[degrees] ground inclination had approximately equivalent effects on the no lift-off region size. Ladder stability was three times more sensitive to tread height than to foot location. Laterally-exerted impulsive hand-tool forces should generally be limited to 8% body weight. These findings can lead to improved ladder designs and safety instructions for stepladder users. Author Affiliation: Biomechanics Research Laboratory, Department of Mechanical Engineering, University of Michigan, 3216 G.G. Brown, 2250 Hayward Street, Ann Arbor, MI 48109-2125, USA

Studies of predictive factors of manual dexterity in adolescents and young adults are lacking. The present longitudinal study reports the relationships between cognitive and behavioural assessments at age 7 years and the schooling, cognitive performance, and manual dexterity at age 17 years. The participants were 65 schoolchildren, 30 boys and 35 girls, from a rural area in France. Assessment at age 7 years included the McCarthy scales and questionnaires measuring the behavior of the child, completed by the mother, the teacher, and the assessing psychologist. Assessment at age 17 years included schooling situation (whether they were in high school or not), cognitive testing (WAIS-R, Trail Making, Verbal Fluency, Cancel H, Stroop, Memory Assessment Scales), and manual dexterity testing (dynamometer, Finger Tapping, Santa Ana Test, Purdue Pegboard). After controlling for effects of parental education and IQ, a negative teachers' rating of children's behaviour and abilities in first-grade grade (7 years) was correlated with early cessation of schooling, but also, unexpectedly, with higher scores for manual dexterity at 17 years. Manual dexterity was not related to cognitive performance at 17 years. It is suggested that the relationship between manual and cognitive performance varies during development. Although manual exploratory behaviour is an important correlate of early cognitive development, manual dexterity is probably not related to later academic performance.

Byline: J. Guillemant (1), H.-T. Le (1), A. Maria (1), A. Allemandou (2), G. Peres (3), S. Guillemant (1) Keywords: Key words:Calcidiol -- Parathyroid hormone -- Puberty -- Vitamin D Abstract: The first part of this study consisted of an 18 month follow-up of the vitamin D status and parathyroid function in a group of 54 French male adolescents, aged from 13 to 16 years old and all pupils of a jockey training school. During the 18 month period four samplings were made, one every 6 months. The first was during September of the first year, the second and third during March and October of the second year, and the last in March of the third year. Therefore we had two main periods: summer and winter. The summer 25-hydroxyvitamin D (25(OH)D) concentrations were higher (71.6 +- 19.9 and 52.4 +- 16.5 nmol/l) than the winter ones (20.4 +- 6.9 and 21.4 +- 6.1 nmol/l). Conversely, the winter intact parathyroid hormone (iPTH) serum levels (4.18 +- 1.18 and 4.11 +- 1.35 pmol/l) were higher than the summer ones (2.44 +- 0.82 and 2.71 +- 0.71 pmol/l). At the two winter time points the 25(OH)D concentrations were lower than 25 nmol/l (10 ng/ml) in 72% (2nd year) and 68% (3rd year) of the adolescents. In the second part of the study we tried a vitamin D.sub.3 supplementation procedure designed to maintain the 25(OH)D and iPTH postsummer serum levels throughout the winter. Pairs of male adolescents matched for height, weight and Tanner pubertal stage were randomly assigned to either vitamin D.sub.3 supplementation (2.5 mg, i.e., 100000 IU) administered orally at three specific periods (end of September, November and January) or no vitamin D.sub.3 treatment (control subjects). Blood was collected just before the first intake of vitamin D.sub.3 and 2 months after the last intake (March). The control subjects had blood drawn at the same time points. In the vitamin D.sub.3-treated subjects, the concentrations of 25 (OH)D (55.3 +- 11.5 nmol/l) and of iPTH (3.09 +- 1.16 pmol/l) in March and September (53.8 +- 12.3 nmol/l and 2.75 +- 1.26 pmol/l) were not significantly different. In the control subjects, March 25(OH)D levels (21.0 +- nmol/l were low, with values below 25 nmol/l in 78% of subjects, and iPTH concentrations (3.97 +- 1.08 pmol/l) were significantly (p&lt 0.001) higher than in September (2.91 +- 0.81 pmol/l). The constant vitamin D wintertime deficiency and wintertime rise in iPTH in adolescent French males throughout puberty has been demonstrated. In adolescents with low dairy calcium intakes, the vitamin D.sub.3 treatment was sufficient to maintain 25(OH)D concentrations at their summer levels throughout winter and to prevent an excessive wintertime rise in iPTH levels. Author Affiliation: (1) Service de Biochimie Medicale, Faculte de Medecine Pitie-Salpetriere, FR (2) AFASEC, Service Medical, Chantilly , FR (3) Service de Physiologie et Medecine du Sport, Hopital de La Pitie, Paris, France, FR Article note: Received: 6 February 2001 / Accepted: 9 May 2001

Byline: M. Sundberg (1), P. GaA'rdsell (2), O. Johnell (2), M. K. Karlsson (2), E. Ornstein (1), B. Sandstedt (1), I. Sernbo (2) Keywords: Key words:Adolescents -- Bone mineral density -- Intervention -- Moderate exercise -- Population-based Abstract: On the basis of cross-sectional studies in elite athletes and longitudinal studies, physical activity in growing children has been suggested to enhance bone mineral acquisition and prevent osteoporosis later in life. The level of exercise in most of these studies is not applicable in a population on a day-to-day basis. The aim of this study was to determine whether moderate increased exercise within the school curriculum from age 12 to 16 years would have anabolic bone effects. In a population-based setting of 40 boys and 40 girls the school curriculum was enhanced to physical education 4 times per week for 3--4 years. Controls were 82 boys and 66 girls who had had physical education twice a week over a corresponding period. Both cases and controls were measured at age 16 years. Bone mineral content (BMC), areal bone mineral density (aBMD), bone size (femoral neck width) and volumetric BMD (vBMD) were measured in total body, spine and femoral neck (FN) by dual-energy X-ray absorptiometry. Data are presented as mean +- SD. BMC (8 +- 15%, p= 0.04), aBMD (9 +- 13%, p= 0.002) and vBMD (9 +- 15%, p= 0.001) were all higher in FN in the male intervention group compared with controls. FN bone size was no higher in the intervention group than in the controls. In girls, no differences were found when comparing the intervention group with controls. The results remained after adjusting for confounding factors such as weight, height, milk intake and activity after school. In summary, we report that increased bone mass can be achieved in a population-based cohort of boys (but not in girls) by moderate increased physical activity within the school curriculum from age 12 to 16 years. We speculate that the same results can be seen in girls if intervention starts at an earlier age. We conclude that increasing the physical education content of the Swedish school curriculum may improve bone mass in at least peripubertal boys. Author Affiliation: (1) Department of Orthopedic Surgery, Hassleholm-Kristianstad, SE (2) Department of Orthopedic Surgery, Malmo University Hospital, Sweden, SE Article note: Received: 20 April 2000 / Accepted: 17 October 2000