Sport-specific musculoskeletal growth and postural control in female artistic gymnasts: a 12 month cohort study

Abstract

Female gymnasts have been evidenced to experience sport-specific growth, of which broad shoulders and narrow hips are common characteristics. In addition to being a central component of handstand performance, postural control mechanisms, including whole-body and lumbo-pelvic stability, have been identified as risk factors for overuse spinal pathology. The study aimed to develop a fundamental understanding of musculoskeletal growth and postural control responses of female artistic gymnasts in order to extend longitudinal insights into overuse spinal pathology risk. Whole-body anthropometric measures were collected for 12 competitive female gymnasts (age at recruitment: nine to 15 years) at three time points across a 12 month period. Musculoskeletal growth was partially defined as the rate of bicristal-to-biacromial breadth ratio development, and informed shoulder- and pelvis-dominant growth sub-groups. Kinematic and kinetic indicators of postural control were determined for a total of 700 handstand trials. The shoulder-dominant (gymnastics-specific) growth group was found to have significantly greater biomechanical risk for general stability (p < 0.001) than the pelvis-dominant group. Significantly greater lumbo-pelvic risk was demonstrated for the pelvis-dominant group (p < 0.001). Extended idiosyncratic examination of proportional sport-specific growth measures alongside multi-faceted risk monitoring was advocated for the effective development of future overuse pathology prevention protocols.     

L'argument économique dans les réformes de l'enseignement en Chine au XXe siècle

Sans résumé     

The Value of the Internet as Entertainment in Five European Countries

We estimate the value of leisure online by applying Goolsbee and Klenow (2006) method to Nielsen Clickstream dataset, which covers the clickstream of more than 12,000 internet users in France, Germany, Italy, Spain and United Kingdom, in 2011. We find that the equivalent variation of welfare from leisure online for the average internet user was between 524 and 785 euros per year. At country level, it amounted to between 18 and 44 billion euros.     

The influence of content knowledge on teaching and learning in Traditional and Sport Education contexts: an exploratory study

Background: Our understanding of the role in which content knowledge (CK) can strengthen instructional models and how that knowledge matters for professional development is limited. It is contended that mere use of an instructional model is insufficient to impact psychomotor learning in meaningful ways.

Purpose: This study was conducted to investigate how a teacher's enacted pedagogical content knowledge (PCK) differed as a function of CK and Sport Education (SE), and to investigate the relative contribution of CK and Sport Education on student learning in terms of swimming performance.

Methods: Four intact classes comprising 88 secondary school students (age: 16–17 years) were randomly assigned to a Traditional, an Sport Education, a Traditional-CK, and a SE-CK group. All classes were taught by the same teacher during a 10-day unit of instruction in the front crawl.

Results: Results showed that the teacher's PCK differed as a function of improved CK. For verbal representations, the amount of cues in the Traditional-CK and SE-CK groups increased about sixfold compared to the Traditional and the SE group. For visual representations, more partially incorrect demonstrations were observed than correct demonstrations in the Traditional and the SE group. More mature and developmentally appropriate tasks were observed in the Traditional-CK and the SE-CK group compared to the Traditional and the SE group. Students in the Traditional-CK and SE-CK groups demonstrated a significant reduction of their amount of strokes on 50?m compared to the Traditional group. A significant interaction effect revealed a larger increase in swimming performance in the CK groups compared to the Traditional and the SE group. Finally, students in the SE group swam significantly more laps than their counterparts in the other groups.

Discussion and conclusion: These results show the impact on student learning when CK was added to both Traditional and Sport Education conditions and contribute to the literature for pre- and in-service teachers. The Sport Education model did not contribute to students’ swimming performance. Students in the Traditional and the SE group did not get the same quality of instruction as students in the Traditional-CK and SE-CK conditions. The latter groups received content that was presented differently both as a presentation and in terms of the actual task. In short, students in the Traditional and Sport Education conditions experienced the content differently than those in the Traditional-CK and SE-CK conditions. These instructional differences resulted in students in the Traditional-CK and SE-CK conditions improving their swimming performances in terms of technical efficiency and in terms of 50?m times.     

Equity,Equality, and Self-Interest in Marital Maintenance

This study investigated the extent to which generalized equity, a reciprocal exchange approach to maintenance (e.g., reward minus costs), and a self-interest approach (e.g., rewards only) were associated with marital satisfaction. An online survey was distributed to 547 heterosexual married individuals. Results supported equity predictions for six maintenance behaviors when using a categorical measure of equity, and for five of the maintenance behaviors when using a linear measure of equity. Counter to predictions, equity and sex did not interact on the use of maintenance. Finally, a combination of equity, reciprocal exchange, and self-interest predicted 57% of the variance in marital satisfaction.