The influence of gate start position on physical performance and anxiety perception in expert BMX athletes

The critical importance of the start phase in bicycle motocross (BMX) racing is increasingly acknowledged. Past experiments underlined that the internal lane of the starting gate provides a strong positional advantage. However, how lane position affects start performance and cognitive and somatic state anxiety remains unexplored. We examined the start performance and anxiety responses of youth national-level BMX riders in both experimental and ecological contexts. We used contextualization motor imagery routines to evaluate start performance and state anxiety from the internal and external lanes. Cycle ergometer measures revealed a better start performance from the external lane, but we did not record any lane effect on actual gate start times. Both somatic and cognitive anxiety scores were higher before racing from the internal compared to the external lane. Finally, state anxiety (i.e., somatic anxiety, worry and concentration disruptions) negatively predicted the start performance. Present findings provide original insights on psychological factors involved in BMX start performance, and might contribute to fruitful coping interventions and training programmes in sports overlapping the framework of “handicap races” taking the specific form of positional advantages/disadvantages at the start (e.g., ski/snowboard cross, athletics, swimming, motorsports, etc.).     

A biomechanical comparison of countermovement performance after short-term traditional and daily-undulated loaded vertical jump training

In order to assess lower extremity muscle mechanical properties in athletes, power-load characteristics during multi-joint tasks are frequently examined. This work compared 6 weeks of traditional (TP) and daily-undulated (DUP) periodized loaded countermovement jumping (CMJ). 20 amateur athletes (age: 24.2 ± 2.6 years, height: 175.6 ± 7.1 cm, body mass: 71.5 ± 7.7 kg, 10 males/10 females) exercised three times weekly using maximal CMJs with loads corresponding to 0%, 15% and 30% of body mass. Prior to the training period, subjects were once-only assigned by random to either the TP or DUP training scheme. Pre-to-post training, maximal center of mass (COM) -height, -take-off velocity, -power output and -impulse were compared during CMJ with additional loads corresponding to 0–30% of body mass. ANOVA (time * group) with repeated measures revealed significant (P < 0.05) temporal gains of maximal COM-height (2–11%), -take-off velocity (1–7%), -power (2–8%) and -impulse (3–9%) over most loading conditions for TP and DUP. However, ANOVA indicated no group effects for any outcome. Independent from the periodization model, maximal power output remained statistically unchanged with increased testing loads. For short-term conditioning periods, TP and DUP were equally effective in enhancing biomechanical jumping variables under varying loading conditions.     

The Swedish riding school: a social arena for young riders

The aim was to explore how young riders experience the riding school. By analysing focus groups interviews, a picture emerged showing that young riders’ main motive for participating at riding schools was the social aspects. Riding schools could be characterized through an institutional perspective in which the young riders became internalized and socialized into a stable culture. The young riders identified with the norms and values of the riding instructors through master–apprentice learning. In addition, the results revealed a change in the stable culture since the instructors encouraged social interactions and participation in the community that became central to learning and development. Opportunities to influence and interact were important for the individuals and from a child’s rights perspective. Through participation in the community of practice at riding schools, young riders not only learn about riding and horse management but also develop important personal social skills.     

An unexpected large continental source of reactive bromine and chlorine with significant impact on wintertime air quality

Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of ‘conventional’ tropospheric oxidants (OH, HO₂ and RO₂) by 26%–73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent.     

Implementation Factors and Their Influence on Student Mathematics Outcomes

Assessing implementation allows for a better understanding of an intervention's effects and the mechanisms that influence its impact. Two main areas of implementation are (a) the quality with which an intervention is delivered and (b) instructors’ adherence to the programmed intervention. The current study used data from a kindergarten mathematics intervention program to (a) examine if and how treatment adherence was associated with implementation quality and (b) explore implementation measures’ relation to student mathematics outcomes. Results indicated high implementation scores across time for both adherence and quality. Neither treatment adherence nor implementation quality was found to relate to a general outcome measure of student mathematics achievement; however, both were similarly related to the curricular-aligned measure.     

Does having vulnerable friends help vulnerable youth? The co-evolution of friendships,victimization, and depressive symptoms in Chinese adolescents' social networks

This study examined whether having vulnerable friends helps or hurts victimized and depressed (i.e., vulnerable) adolescents and whether this depends on classroom supportive norms. Students (n = 1461, 46.7% girls, 93.4% Han nationality) were surveyed four times from seventh and eighth grade (M_age = 13 years) in 2015 and 2016 in Central China. Longitudinal social network analyses indicated that having vulnerable friends can both hurt and help vulnerable adolescents. Depressed adolescents with depressed friends increased in victimization over time. Victimized adolescents with victimized friends increased in victimization but decreased in depressive symptoms. These processes were most likely in classrooms with high supportive norms. Having friends and a supportive classroom may hurt vulnerable adolescents' social position but help victims' emotional development.