Dynamic balance performance varies by position but not by age group in elite Rugby Union players – a normative study

This cohort study aimed to provide normative Y Balance Test scores for an elite Rugby Union population, while investigating the effect player age groups (senior/under-20), playing positions (forwards/backs) and anthropometrics (height and body mass) had on performance. Two-hundred and sixty-one elite male under-20 (n = 50) and senior (n = 211) players completed baseline Y Balance Test during the 2015/2016 season. One-way ANCOVA and post-hoc t-tests were used to investigate the effect playing position, player group, height and weight had on performance. The cohort was then stratified into groups (age group and/or playing position), and normative percentiles were presented. There was a statistically significant difference (p < 0.05) in Y Balance Test performance between playing positions, when controlling for age group. This difference did not remain when controlling for player body mass. Post-hoc analysis demonstrated that backs had a longer normalised reach distance, with medium-large and small-medium effect sizes for the under-20 and senior cohorts respectively. The one-way ANCOVA analysis suggests that this difference is likely due to the larger differences in player body mass between forward and back playing positions. The normative values presented in this paper may be used by clinicians and researchers to aid injury prevention and rehabilitation strategies.     

Comparison of Indirect Calorimetry- and Accelerometry-Based Energy Expenditure during Object Project Skill Performance

This study compared the energy expenditure (EE) levels during object projection skill performance (OPSP) as assessed by indirect calorimetry and accelerometry. Thirty-four adults (female n = 18) aged 18–30 (23.5 ± 2.5 years) performed three, 9-min sessions of kicking, over-arm throwing, and striking performed at 6-, 12-, and 30-sec intervals. EE was estimated (METS) using indirect calorimetry (COSMED K4b2) and hip-worn accelerometry (ActiGraph GT3X+). EE using indirect calorimetry demonstrated moderate-intensity physical activity (3.4 ± 0.7 METS––30-sec interval, 5.8 ± 1.2 METS––12-sec interval) to vigorous intensity physical activity (8.3 ± 1.7 METS––6-sec interval). However, accelerometry predicted EE suggested only light-intensity physical activity (1.7 ± 0.2 METS––30-sec interval, 2.2 ± 0.4 METS––12-sec interval, 2.7 ± 0.6 METS––6-sec interval). Hip-worn, ActiGraph GT3X+ accelerometers do not adequately capture physical activity intensity levels during OPSP, regardless of differences in skill performance intervals.     

Pedagogies of Black Eldership: Exploring the Impact of Intergenerational Contact on Youth Research

This article examines the interactions between a collective of self-described “African American,” “multiracial,” and “African immigrant” high school youth researchers, and two African American community elders. Drawing from a year-long critical ethnographic study of the youth research collective, the author documents how pedagogies of Black eldership overlapped with youth participatory action research to open new possibilities for preparing youth as researchers. The study highlights how an out-of-school educational space afforded alternative pedagogical opportunities by specifically examining how pedagogies of Black eldership helped youth researchers historicize and politicize their research, pushing them to move from embodied knowledge to self-knowledge. Drawing from African-centered and critical theory, the study explicates aspects of the pedagogies of Black eldership. Without bounding these pedagogies, the author uses two narratives of teaching and learning to illustrate how intergenerational contact impacted the trajectory of the youth researchers. They transformed their research after meeting with the elders to be more introspective and examine how their worldviews were being constructed and influenced. The findings in this study serve as an impetus for further research examining the educational context of Black eldership and youth research.     

Children with attention-deficit/hyperactivity disorder: A review of the literature on social skills deficits

Social interactions between children with Attention-Deficit/Hyperactivity Disorder (AD/HD) and their teachers, peers, and parents are discussed. The extent to which these interactions may be termed problematic may depend on the social skills deficits displayed by this population. Although the general trend in the liternature has been to examine and describe children with deficient social skills, changing the focus to children with AD/HD who are not experiencing these difficulties may prove beneficial. A review of the previous literature is discussed, as well as suggestions for practice and future research needs.     

Facilitation of appetitive conditioning with naturalistic conditioned stimuli: CS and US factors

Adding limited female cues to a conditioned stimulus (CS) facilitates conditioned male sexual responding. In two experiments, we examined the mechanisms of this facilitation effect. The color of the female cues on the CS was varied in Experiment 1. Similarity between the CS plumage color and the color of the live female (the unconditioned stimulus [US]) could only partially account for the results. The extent to which the facilitation effect represents a specialization of sexual behavior was examined in Experiment 2 by comparing conditioning with either food or copulation as the US. The CSs with female cues elicited more approach and grab responses regardless of which US was used. However, uniquely sexual conditioned responses (mounts and cloacal contacts) were enhanced only when sexual reinforcement served as the US. These findings suggest that the facilitation effect of female cues represents a general feature of appetitive behavior systems.     

Contributions of joint rotations to racquet speed in the tennis serve

The purpose of this study was to measure the contributions of the motions of body segments and joints to racquet head speed during the tennis serve. Nine experienced male players were studied using three-dimensional film analysis. Upper arm twist orientations were calculated with two alternative methods using joint centres and skin-attached markers. The results showed that skin-attached markers could not be used to calculate accurate upper arm twist orientations due to skin movement, and that the use of joint centres produced errors of more than 20 degrees in the upper arm twist orientation when the computed elbow flexion/extension angle exceeded 135 degrees in the final 0.03 s before impact. When there were large errors in the upper arm twist orientation, it was impossible to obtain accurate data for shoulder or elbow joint rotations about any axis. Considering only the contributors that could be measured within our standards of acceptable error, the approximate sequential order of main contributors to racquet speed between maximum knee flexion and impact was: shoulder external rotation, wrist extension, twist rotation of the lower trunk, twist rotation of the upper trunk relative to the lower trunk, shoulder abduction, elbow extension, ulnar deviation rotation, a second twist rotation of the upper trunk relative to the lower trunk, and wrist flexion. The elbow extension and wrist flexion contributions were especially large. Forearm pronation made a brief negative contribution. Computed contributions of shoulder internal rotation, elbow extension and forearm pronation within the final 0.03 s before impact were questionable due to the large degree of elbow extension. Near impact, the combined contribution of shoulder flexion/extension and abduction/adduction rotations to racquet speed was negligible.