Youth helmet design in sports with repetitive low- and medium-energy impacts: a systematic review

Concussion awareness in youth sports has increased secondary to recent legislation, public health campaigns, and media coverage. The potential for long-term negative sequelae is now widely recognized and there have been a number of initiatives nationwide to prevent pediatric head injuries, including efforts to design more effective helmets for repetitive impact sports. The primary aim of this review is to systematically assess the literature regarding helmet design in youth sports specifically designed to mitigate repetitive low- and medium-energy impacts. Secondary aims include identifying areas for future research and opportunities for helmet design improvement. A systematic review of the literature was performed to identify articles relating to youth helmet design and biomechanical studies of concussion in youth sports. Pubmed, Google scholar, Cochrane Review and article citations were used to identify all pertinent English articles between 1971 and January 2016. A total of 14 studies met criteria for inclusion in this review, three of which included clinical outcomes (all Level of Evidence II) and eleven of which included biomechanical outcomes. The vast majority focused on adolescents playing football. Six of the biomechanical studies demonstrated improved biomechanical metrics in helmets with increasing foam thickness and number of foam layers. Two clinical studies also seem to support this concept, with significant caveats. To date, there are limited clinical and biomechanical data on youth helmet design. There is a need for further research in order to optimize helmet design and reduce the number and severity of pediatric sports-related head injuries.     

The effectiveness of front fork systems at damping accelerations during isolated aspects specific to cross-country mountain biking

Cross-country mountain bike suspension reportedly enhances comfort and performance through reduced vibration and impact exposure. This study analysed the effectiveness of three different front fork systems at damping accelerations during the crossing of three isolated obstacles (stairs, drop, and root). One participant completed three trials on six separate occasions in a randomised order using rigid, air-sprung, and carbon leaf-sprung forks. Performance was determined by time to cross obstacles, while triaxial accelerometers quantified impact exposure and damping response. Results identified significant main effect of fork type for performance time (p < 0.05). The air-sprung and leaf-sprung forks were significantly slower than the rigid forks for the stairs (p < 0.05), while air-sprung suspension was slower than the rigid for the root protocol (p < 0.05). There were no differences for the drop protocol (p < 0.05). Rigid forks reduced overall exposure (p < 0.05), specifically at the handlebars for the stairs and drop trials. More detailed analysis presented smaller vertical accelerations at the handlebar for air-sprung and leaf-sprung forks on the stairs (p < 0.05), and drop (p < 0.05) but not the root. As such, it appears that the suspension systems tested were ineffective at reducing overall impact exposure at the handlebar during isolated aspects of cross-country terrain features which may be influenced to a larger extent by rider technique.     

Effects of aerobic exercise on overweight children's cognitive functioning: a randomized controlled trial

The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control condition. Exercise sessions met 5 days/week for 15 weeks. The Cognitive Assessment System (CAS), a standardized test of cognitive processes, was administered individually before and following intervention. Analysis of covariance on posttest scores revealed effects on executive function. Group differences emerged for the CAS Planning scale (p = .03). Planning scores for the high-dose group were significantly greater than those of the control group. Exercise may prove to be a simple, yet important, method of enhancing aspects of children's mental functioning that are central to cognitive and social development.     

Sport-Related Identities and the "Toxic Jock"

Little attention has been paid to the multidimensional nature of athletic involvement, which includes identity formation as well as participation in sports activities. Five hundred eighty-one sport-involved undergraduate students completed a questionnaire assessing their sport-related identities, goal orientations, primary sport ratings, and conformity to masculine norms. F-tested mean comparisons and hierarchical linear regressions were used to explore the characteristics associated with two distinct sport-related identities ("athletes" and "jocks"). Jock identity was associated with an ego-oriented approach to sports (men only), whereas athlete identity was associated with a task-oriented approach (both genders). Jock identity was positively associated with conformity to masculine norms, particularly for men, whereas athlete identity was positively associated with some masculine norms (i.e., Winning) and negatively associated with others (i.e., Playboy). These findings help to identify the correlates of a "toxic Jock" identity that may signal elevated risk for health-compromising behavior.     

Temporal coding affects transfer of serial and simultaneous inhibitors

In three experiments with rats, the temporal relationships under which a conditioned inhibitor would transfer its inhibitory potential to an independently trained excitor in a summation test were investigated. Each experiment varied the temporal relationship between the inhibitor and the transfer excitor at test (serial or simultaneous) and, in addition, manipulated either the inhibitor-training excitor (serial or simultaneous), training excitor-unconditioned stimulus (US) (trace or delay), or the transfer excitor-US (trace or delay) temporal relationships. Conditioned inhibition was found only when the no-US expectation evoked by the conditioned inhibitor was temporally aligned with the US expectation evoked by the transfer excitor, independent of whether the inhibitor was trained as a serial or simultaneous signal for US omission. Results are discussed in terms of the temporal coding hypothesis and the comparator hypothesis.     

Embracing Death: Mexican Parent and Child Perspectives on Death

A mixed-method approach was used to explore parent and child perspectives on death in Mexico. Parents’ and children’s death-related experiences and understanding of death were examined. While all children in this sample displayed a biological understanding of death, older children were less likely to endorse that all living things die. Children also displayed coexistence of beliefs related to death that can be attributed to both their biological and spiritual understanding of death. We also found that older children were more likely to report that a child should feel sad following the death of a loved one. These findings highlight how cultural practices shape the development of cognitive and affective processes related to death.