THE EFFECT OF REPRESENTATIVE TASK DESIGN ON GROUND REACTION FORCES PRODUCED BY ADOLESCENT RUGBY PLAYERS

Our primary aim in this study was to investigate differences in the ground reaction forces (GRFs) produced when adolescent rugby players performed match-reflective tasks of increasing degrees of representativeness. Fourteen male players performed three tasks; a straight jog, an anticipated cut and an unanticipated cut. These tasks were performed in four different conditions; landing with their dominant or non-dominant leg, while carrying or not carrying a rugby ball. Greater GRFs were recorded during both the weight acceptance and late push-off phases of the cutting tasks compared with the straight jog and during the push-off phase when the direction of the cut was anticipated. Carrying a ball, however, did not affect the GRFs recorded. These findings highlight the importance of employing representative task design when assessing performance and designing practice

BIOMECHANICAL ANALYSIS OF ELITE FEMALE RUGBY PLACE KICKERS

The purpose of this study was to investigate rugby place kicking technique of elite female players. Five International-level female place kickers took at least five maximum range place kicks, and their technique was analysed using 3D motion capture. In comparison to successful male kickers, females achieved slower kicking foot and ball velocities and shorter maximum kicking distances. Reduced extension of the support leg hip and knee joints, combined with slower centre of mass deceleration, meant that females appeared to transfer less momentum from their approach to the ball, thus, requiring them to perform more positive work at their kicking hip. A faster approach to the ball and more pronounced support leg extension may enable females to achieve greater place kicking distances

EFFECTS OF FATIGUE ON RUGBY PLACE KICKING TECHNIQUE AND PERFORMANCE

The aim of this study was to identify differences in place kicking performance and technique following a rugby-specific fatigue protocol. Three skilled place kickers performed four blocks of the protocol, between which they took three place kicks from a challenging pitch location. The success of the kicks, measures of physical exertion and lower body and torso kinematic variables were measured. Kicking success dropped following blocks 2 and 4 of the protocol, all missed kicks were wide of the goalposts. Individual differences were apparent. After block 2 the kickers demonstrated greater upper body motion, potentially a strategy to obtain fast foot velocity but at a detriment to accuracy. After block 4, collapse of the stance leg was observed which may have impacted the kickers’ stability. Further research with more participants and a specific focus on muscular fatigue is required

Situations and mechanisms of non-contact knee injury in adult netball: A systematic review

Objectives Noncontact knee injuries in netball are a concern due to a range of negative consequences. To reduce the number of injuries, identifying the situation and mechanism of injury is important. This systematic review examined the literature reporting the situation and mechanism of noncontact knee injury in netball. Design Systematic Review. Methods PRISMA guidelines were followed and specific key-term combinations used to search databases. Descriptive and analytic-observational studies reporting the situation or mechanism of noncontact knee injury in females playing netball were included (evaluated using frequency counts). Results Six articles were included (combined sample 11,401). Players self-reported the situation of injury in five studies, only one study reported both the situation and mechanism of injury. Landing was the most reported situation of knee injury, representing 46.6% of all knee injuries whilst knee abduction (valgus) collapse was the most observed mechanism. Situation and mechanism of noncontact knee injury in netball were not adequately reported. Conclusions Despite the variations in reporting methods, landing is the most common situation of injury. As only one study reported mechanism of injury, it is difficult to draw conclusions but the mechanism of noncontact knee injury in netball appears similar to those identified in other female athletes

Equilibrium and nonequilibrium fluctuations at the interface between two fluid phases

We have performed small-angle light-scattering measurements of the static structure factor of a critical binary mixture undergoing diffusive partial remixing. An uncommon scattering geometry integrates the structure factor over the sample thickness, allowing different regions of the concentration profile to be probed simultaneously. Our experiment shows the existence of interface capillary waves throughout the macroscopic evolution to an equilibrium interface, and allows to derive the time evolution of surface tension. Interfacial properties are shown to attain their equilibrium values quickly compared to the system's macroscopic equilibration time.Comment: 10 pages, 5 figures, submitted to PR

A cross-sectional retrospective survey of injury situation and prevalence in female recreational netball players with a focus on knee injuries

Objectives: To examine situations of injury and injury prevalence in female adult recreational netball players with a focus on knee injuries. Design: Cross sectional retrospective online survey. Participants: 193 female adult recreational netball players. Main outcome measures: Any injury sustained in the previous 12 months, situation of injury, any knee injuries sustained in the previous five years, the length of time unable to play netball, and knee injury management. Results: In the previous 12 months, 61% of respondents sustained injury to the lower limb, and 27% to the upper limb. Lower limb injury situations were mostly landings (46%). Upper limb injury situations were mostly collisions with an opponent (27%). 46% reported sustaining a knee injury in the previous five years. Following knee injury, players were unable to play netball for 6.8 ± 7.0 months (training); and 8.2 ± 7.4 months (matches) respectively. Conclusions: Lower limb injury is more common than upper limb injury in recreational adult female adult netball players. Landing was the most common situation of injury for the lower limb including knee injuries. In the previous five years, nearly half of the players had sustained a knee injury resulting in more than six months out of the game

The Effect of Attentional Focus Instructions on Performance and Technique in a Complex Open Skill

External focus of attention has been shown to promote more automatic motor control, yielding better performance and more efficient technique, than an internal focus (Wulf, 2013). However, most research has used closed-skill tasks in novices. The extent to which the reported pattern of findings generalises to more complex, time-constrained tasks requires further investigation. In this study we investigated the effect of attentional focus instructions on performance and technique in an open-skill task in skilled performers. Thirteen skilled cricket batters batted from a ball projector in four conditions, receiving instructions to focus on the movement of their hands (internal focus), the movement of their bat (proximal external focus), the flight of the ball (distal external focus), or no instruction (control). Performance and technique were measured by quality of bat-ball contacts and step length/knee flexion, respectively, whilst playing straight drives. Compared to external focus and control conditions, focusing internally yielded significantly worse batting performance and shorter step lengths, with the largest effects observed between internal and distal external focus conditions. Quality of bat-ball contact data suggested that participants’ ability to protect the wicket (as evidenced by more miss/edge shots) was more negatively affected by focusing internally than their ability to play shots to score runs (as evidenced by fewer good bat-ball contacts). Findings suggest that, for skilled performance of open-skill tasks, a distal external focus yields more effective performance and technique compared with focusing internally. Findings highlight the need for further research on attentional focus effects between different skills within specific sports

Uncovering the link between the SpnIII restriction modification system and LuxS in Streptococcus pneumoniae meningitis isolates

Streptococcus pneumoniae is capable of randomly switching their genomic DNA methylation pattern between six distinct bacterial subpopulations (A-F) via recombination of a type 1 restriction-modification locus, spnIII. These pneumococcal subpopulations exhibit phenotypic changes which favor carriage or invasive disease. In particular, the spnIIIB allele has been associated with increased nasopharyngeal carriage and the downregulation of the luxS gene. The LuxS/AI-2 QS system represent a universal language for bacteria and has been linked to virulence and biofilm formation in S. pneumoniae. In this work, we have explored the link between spnIII alleles, the luxS gene and virulence in two clinical pneumococcal isolates from the blood and cerebrospinal fluid (CSF) of one pediatric meningitis patient. The blood and CSF strains showed different virulence profiles in mice. Analysis of the spnIII system of these strains recovered from the murine nasopharynx showed that the system switched to different alleles commensurate with the initial source of the isolate. Of note, the blood strain showed high expression of spnIIIB allele, previously linked with less LuxS protein production. Importantly, strains with deleted luxS displayed different phenotypic profiles compared to the wildtype, but similar to the strains recovered from the nasopharynx of infected mice. This study used clinically relevant S. pneumoniae strains to demonstrate that the regulatory network between luxS and the type 1 restriction-modification system play a key role in infections and may support different adaptation to specific host niches.Hannah N. Agnew, John M. Atack, Ann R.D. Fernando, Sophie N. Waters, Mark van der Linden, Erin Smith, Andrew D. Abell, Erin B. Brazel, James C. Paton, and Claudia Trappett