The Rise in Single-Mother Families and Children’s Cognitive Development: Evidence From Three British Birth Cohorts

This article assessed changes in the association between single motherhood and children’s verbal cognitive ability at age-11 using data from three cohorts of British children, born in 1958 (n = 10,675), 1970 (n = 8,933) and 2000 (n = 9,989), and mediation analysis. Consistent with previous studies, direct effects were small and insignificant. For those born in 1958 and 1970 indirect effects, operating through reduced economic and parental resources, were associated with −.107-SD to −.156-SD lower attainment. Differences between the two cohorts, and by children’s age when parents separated, were insignificant. For the 2000 cohort, effect sizes for children born to single mothers did not change significantly (−.112-SD) but attenuated for children whose parents separated in early childhood (−.076-SD) or while of school age (−.054-SD).     

Does modality matter? A latent profile and transition analysis of sedentary behaviours among school-aged youth: The UP&DOWN study

ABSTRACT

The aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time.     

山西省青少年武术套路运动员无氧能力特征的研究

文章通过对山西省武术管理中心16名青少年武术套路运动员进行了无氧功测试、血乳酸测试,测试所获数据采用秩和检验进行组间均数比较,并对wingate结果和血乳酸结果进行相关性检验,得出结论：（1）青少年武术套路运动员的无氧能力并不是影响成绩的主要因素。（2）青少年武术套路运动员的无氧能力相比体能占主导的无氧运动而言较差。（3）wingate测试的各项指标采用其体重相对值更能反映运动员之间无氧能力的差别。（4）运动后7分钟的血乳酸水平可以反应青少年武术套路运动员的无氧能力水平。     

改进青少年网球运动员正手上旋球技术教学训练方法的研究

文章运用文献综述法、专家访谈法、分析对比法、实验法对网球运动员进行实际的正手上旋球教学环节的实验检测,并对正手上旋球技术进行观察分析,旨在通过教学实验得出一套科学合理并具有针对性的提高青少年网球运动员正手上旋球的教学训练方法。     

Association of different types of playing surfaces with bone mass in growing girls

The aim of this cross-sectional study was to compare bone mass in young female athletes playing ball games on different types of playing surfaces. About 120 girls, 9–13 years of age (10.6 ± 1.5 years old Tanner I–III) were recruited and divided into prepubertal and pubertal groups. The sample represented 3 groups of athletes: soccer (N = 40), basketball (N = 40), and handball (N = 40); and 6 different playing surfaces (soccer – ground, soccer – artificial turf, basketball – synthetic, basketball – parquet, handball – synthetic, and handball – smooth concrete). Total and regional body composition (bone mass, fat mass, and lean mass) were measured by dual-energy X-ray absorptiometry (DXA). The mechanical properties of the surfaces (force reduction, vertical deformation, and energy return) were measured with the Advanced Artificial Athlete (Triple A) method. The degree of sexual development was determined using Tanner test. The pubertal group showed that soccer players on the ground, basketball players on synthetic, and handball players on smooth concrete had higher values of bone mineral content (BMC) and bone mineral density (BMD) (P < 0.05) than the soccer players on the artificial turf, basketball players on parquet, and handball players on synthetic. In conclusion, a hard playing surface, with less vertical deformation and force reduction, and greater energy return, is associated with higher levels of BMD and BMC in growing girls, regardless of the sport they practice.     

Sexual dimorphism in bone–muscle relationship in young adults

The purpose of this study was to analyse associations between lean soft tissue (LST), a surrogate of skeletal muscle mass and key fracture-related geometric characteristics of the proximal femur. Moreover, we examined the role that muscle played on the proximal femur geometry in response to physical activity (PA). Participants were 83 young adults. Leg LST (exposure) was assessed by dual energy X-ray absorptiometry (DXA). Proximal femur geometry was derived from a left hip DXA scan. Geometric variables (outcomes) included the femoral neck axis length (FNAL), the femoral neck width (FNW), the neck–shaft angle and FNW|FNAL (an index of robustness). PA was evaluated by accelerometry. Linear regression was used to analyse relationships. Additional exposure variables included body height and mass. In males, leg LST explained 17.4% of variation in FNAL (P < 0.001) and 15% in FNW (P = 0.015). In females, it explained 8.8% of the variance in FNAL (P = 0.020). Associations remained significant in males, but not in females, when vigorous PA was added to the models. These results suggest that public health approaches to promote PA may be particularly important in females since vigorous PA seems to convey advantages in femur geometry and consequently in bone strength.     

Motivation and Exercise Dependence

The objective of this study was to use self-determination theory to analyze the relationships of several motivational variables with exercise dependence. The study involved 531 exercisers, ranging in age from 16 to 60 years old, who responded to different questionnaires assessing perception of motivational climate, satisfaction of basic psychological needs, motivation types, and exercise dependence. The results of multiple mediation analysis revealed that ego-involving climate and perceived competence positively predicted exercise dependence in a directed and mediated manner through introjected and external regulation. Gender and age did not moderate the analyzed relationships. These results allow us to better understand the motivational process explaining exercise dependence, demonstrating the negative influence of the ego-involving climate in the context of exercise.     

Skeleton Changes Induced by Horse Riding on Medieval Skeletal Remains from Croatia

Skeletal remains of 35 individuals from the Croatian excavation site Kamen Most – Kaldrma from the fourteenth to fifteenth centuries were analyzed anthropologically. Due to specific skeletal characteristics, eight of them were analyzed in great detail in this study. The results of additional analysis indicated that all bone elements, except pelves, of all eight persons belonged to males. All pelvic girdle have characteristics of female sex and pronounced muscle attachments that are both indicative of horse riding. All eight persons had at least two of six changes on femora indicative of horse riding. Vertebrae of seven persons (one person did not have preserved vertebrae) have Schmorl's nodes. Signs of advanced osteoarthritis were found on all joints in all eight persons. All of them also have visible signs of periostitis especially on lower extremities. Pathological signs of trauma were found in five persons. Two of them had skull fractures and the rest had fractures of extremities which are also characteristic for horse riders. The average age of all eight persons was above 45 years at death. DNA analysis confirmed male sex for seven individuals. The results were additionally confirmed by later archeological findings of tombstones with illustrations of horse riders.     

‘Governmentality’ in the origins of European female PE and sport: the Spanish case study (1883–1936)

The purpose of the paper is twofold: (1) to contribute to the analysis of the origins of modern European female PE and sports from a power perspective, inspired by Foucault's work; and (2) to present a detailed analysis of female PE and sport in Spain (1883–1936) as a specific European case study. It is argued that these physical activities could be conceived in the Spanish case as part of a specific kind of ‘governmentality’ with a dual nature. On the one hand they represented disciplinary ‘technologies of power’ over the female body. Selected physical activities—dictated mainly from the hygienic-moral position of the Regeneracionistas (‘Regenerationists’)—were exerted as a kind of ‘bio-power’ for the control of the female population. On the other hand, such kind of activities (especially sports) represented certain ‘technologies of the self’ for middle and upper class women. Through participation in sports, women gained a more active and public role in the Spanish society of the era, obtaining some degree of autonomy in self-governance over their bodies and their lives.