Comparing critical speed modelling approaches and exploring relationships with match-play variables in elite male youth soccer players

Background

A novel bi-exponential method has emerged to estimate critical speed (CS) and D-prime (D') from a 3-min all-out test (3MT).

Objectives

To compare CS analysis methods to determine whether parameter estimations were interchangeable. Reference values and relationships with key soccer match-play variables were explored.

Methods

Thirteen elite male youth (14-15 years old) players completed a 30 m shuttle run 3MT to estimate CS, D', rate of speed decline time constant, maximal speed (S _max), time to S _max (t _max), and fatigue index (FI), using the traditional method and bi-exponential model on average (Bi-Exp_Average) and max speed settings (Bi-Exp_Max-Speed). High-speed running (HSR) and sprinting distances and counts, and the number of accelerations were collected from two matches. Magnitude-based inferences (p < 0.05) with smallest worthwhile change of 0.2 effect sizes were used to analyse differences. Pearson's and Spearman's correlation coefficients were used to measure associations between CS model variables and match-play parameters.

Results

There were significant differences between the traditional method and both bi-exponential models for CS and D', as well as between the bi-exponential models for all variables except t _max. Using the Bi-Exp_Average model, strong correlations (r = 0.70-0.73; p < 0.05) were observed for D' and FI with the number of standardised and individualised HSRs, respectively. With the Bi-Exp_Max-Speed model, there were strong correlations (r/ρ = 0.64-0.68; p < 0.05) between D' and the number of standardised HSRs and sprints, and the number of individualised sprints.

Conclusion

There is a lack of interchangeability between analysis methods. It appears that D' and FI from the bi-exponential models could be associated with high-intensity actions in soccer match-play.

Applied Sport Science for Male Age-Grade Rugby Union in England

Rugby union (RU) is a skill-collision team sport played at junior and senior levels worldwide. Within England, age-grade rugby governs the participation and talent development of youth players. The RU player development pathway has recently been questioned, regarding player performance and well-being, which sport science research can address. The purpose of this review was to summarise and critically appraise the literature in relation to the applied sport science of male age-grade RU players in England focussing upon (1) match-play characteristics, (2) training exposures, (3) physical qualities, (4) fatigue and recovery, (5) nutrition, (6) psychological challenges and development, and (7) injury. Current research evidence suggests that age, playing level and position influence the match-play characteristics of age-grade RU. Training exposures of players are described as 'organised chaos' due to the multiple environments and stakeholders involved in coordinating training schedules. Fatigue is apparent up to 72 h post match-play. Well-developed physical qualities are important for player development and injury risk reduction. The nutritional requirements are high due to the energetic costs of collisions. Concerns around the psychological characteristics have also been identified (e.g. perfectionism). Injury risk is an important consideration with prevention strategies available. This review highlights the important multi-disciplinary aspects of sport science for developing age-grade RU players for continued participation and player development. The review describes where some current practices may not be optimal, provides a framework to assist practitioners to effectively prepare age-grade players for the holistic demands of youth RU and considers areas for future research.

The Effects of Augmented Feedback on Sprint, Jump, and Strength Adaptations in Rugby Union Players After a 4-Week Training Program

PURPOSE

Feedback can enhance acute physical performance. However, its effects on physical adaptation have received little attention. Therefore, the purpose of this study was to determine the effect of feedback during a 4-wk training program on jump, sprint, and strength adaptations.

METHODS

A total of 28 semiprofessional male rugby union players were strength-matched into 2 groups (feedback and nonfeedback). During the 4-wk training program, the Feedback group received immediate, objective feedback on (1) mean concentric velocity during resistance training repetitions, (2) distance feedback for standing broad jumps, and (3) time for sprints. The Nonfeedback group was not provided additional information. Across the 4-wk mesocycle, subjects completed 3 strength and conditioning sessions per week. Countermovement jump, standing long jump, 10- and 20-m sprint, and 3-repetition-maximum barbell back squat and bench press were measured before and after the training intervention. Magnitude-based inferences assessed meaningful changes within and between groups.

RESULTS

The Feedback group showed small to moderate improvements in outcome measures, whereas the Nonfeedback group demonstrated trivial to small improvements. Improvements in countermovement-jump relative peak power (effect size ± 90% confidence limits: 0.34 ± 0.42), 10-m (0.20 ± 0.35) and 20-m sprints (0.40 ± 0.21), and 3-repetition-maximum back squats (0.23 ± 0.17) were possibly to likely greater for the Feedback condition than for Nonfeedback.

CONCLUSIONS

Providing augmented feedback during strength and conditioning routines can enhance training adaptations compared with athletes who do not receive feedback. Consequently, practitioners should consider providing kinematic outputs, displacement, or sprint time at the completion of each repetition as athletes train.

Acceptability of a new practice development for radiographers focussed on reducing 'never events' related to nasogastric feeding tubes in adult patients

INTRODUCTION

Ascertain if a new practice development designed to reduce 'never events' from feeding through misplaced nasogastric tubes (NGT) in a large teaching hospital Trust was acceptable to a large radiography workforce.

METHODS

Despite National Patient Safety Agency guidance advising on safe practice for confirming position of NGTs a number of 'never events' still occur nationally due to misinterpretation of the check X-ray. A new practice development for radiographers included providing an immediate comment and removal of misplaced NGTs at the time of the check X-ray examination. Success of the new system was partly assessed using qualitative and quantitative measures of radiographer opinion of the training and different aspects of the system.

RESULTS

There was a significant improvement in radiographers' level of confidence in image interpretation after training (58/98 positive responses before, 89/98 positive after training) and after five months of experience at undertaking the role (96/98 positive) (p < 0.01). There was increased confidence in NGT removal post training and with five months of experience (16/95 positive before training, 67/96 positive after and 81/95 positive with five months of experience). 97/98 (99%) of radiographers agreed the new system benefits patients, 93/98 (95%) believed it a positive step for the radiography profession.

CONCLUSION

Evaluation of this new practice development has shown it was embraced by radiographers and is a workable and potentially cost-effective solution in addressing real time image interpretation issues that were evident from previous 'never events'. Large scale implementation of this system across the NHS Radiography workforce should be considered.

Changes in markers of fatigue following a competitive match in elite academy rugby union players

Background: Post-match fatigue has yet to be investigated inacademy rugby union players.Objectives: To determine the magnitude of change in upper-(plyometric push-up (PP) flight-time) and lower-body(countermovement jump (CMJ) mean power) neuromuscularfunction (NMF), whole blood creatine kinase (CK) and perceptionof well-being following a competitive match in academy rugbyunion players.Methods: Fourteen academy rugby union players participatedin the study. Measures were taken 2 h pre-match (baseline) andimmediately post-match. Further testing was also undertaken at24-, 48- and 72 h respectively post-match. Changes in measuresfrom baseline were determined using magnitude-based inferences.Results: Decreases in CMJ mean power were likely substantialimmediately (-5.5±3.3%) post-match, very likely at 24 h (-7±3.9),likely at 48 h (-5.8±5.4), while likely trivial at 72 h (-0.8±3.8)post-match. PP flight-time was very likely reduced immediately(-15.3±7.3%) and 24 h (-11.5±5.7%) post-match, while possiblyincreased at 48 h (3.5±6.0%) and likely trivial at 72 h (-0.9±5.4%)post-match. Decreases in perception of well-being were almostcertainly substantial at 24 h (-24.0±4.3%), very likely at 48 h(-8.3±5.9%), and likely substantial at 72 h (-3.6±3.7%) post-match.Increases in CK were almost certainly substantial immediately(138.5±33%), 24 h (326±78%) and 48 h (176±62%) post-match,while very likely substantial at 72 h (57±35%) post-match.Conclusion: These findings demonstrate the transient andmultidimensional nature of post-match fatigue in academyrugby union players. Furthermore, the results demonstrate theindividual nature of recovery, with many players demonstratingdifferent recovery profiles from the group average.Keywords: collision sport, monitoring, sports injuries

ENCODE data at the ENCODE portal

The Encyclopedia of DNA Elements (ENCODE) Project is in its third phase of creating a comprehensive catalog of functional elements in the human genome. This phase of the project includes an expansion of assays that measure diverse RNA populations, identify proteins that interact with RNA and DNA, probe regions of DNA hypersensitivity, and measure levels of DNA methylation in a wide range of cell and tissue types to identify putative regulatory elements. To date, results for almost 5000 experiments have been released for use by the scientific community. These data are available for searching, visualization and download at the new ENCODE Portal (www.encodeproject.org). The revamped ENCODE Portal provides new ways to browse and search the ENCODE data based on the metadata that describe the assays as well as summaries of the assays that focus on data provenance. In addition, it is a flexible platform that allows integration of genomic data from multiple projects. The portal experience was designed to improve access to ENCODE data by relying on metadata that allow reusability and reproducibility of the experiments.

The UCSC Genome Browser database: extensions and updates 2013

The University of California Santa Cruz (UCSC) Genome Browser (http://genome.ucsc.edu) offers online public access to a growing database of genomic sequence and annotations for a wide variety of organisms. The Browser is an integrated tool set for visualizing, comparing, analysing and sharing both publicly available and user-generated genomic datasets. As of September 2012, genomic sequence and a basic set of annotation 'tracks' are provided for 63 organisms, including 26 mammals, 13 non-mammal vertebrates, 3 invertebrate deuterostomes, 13 insects, 6 worms, yeast and sea hare. In the past year 19 new genome assemblies have been added, and we anticipate releasing another 28 in early 2013. Further, a large number of annotation tracks have been either added, updated by contributors or remapped to the latest human reference genome. Among these are an updated UCSC Genes track for human and mouse assemblies. We have also introduced several features to improve usability, including new navigation menus. This article provides an update to the UCSC Genome Browser database, which has been previously featured in the Database issue of this journal.

The UCSC Genome Browser database: extensions and updates 2011

The University of California Santa Cruz Genome Browser (http://genome.ucsc.edu) offers online public access to a growing database of genomic sequence and annotations for a wide variety of organisms. The Browser is an integrated tool set for visualizing, comparing, analyzing and sharing both publicly available and user-generated genomic data sets. In the past year, the local database has been updated with four new species assemblies, and we anticipate another four will be released by the end of 2011. Further, a large number of annotation tracks have been either added, updated by contributors, or remapped to the latest human reference genome. Among these are new phenotype and disease annotations, UCSC genes, and a major dbSNP update, which required new visualization methods. Growing beyond the local database, this year we have introduced 'track data hubs', which allow the Genome Browser to provide access to remotely located sets of annotations. This feature is designed to significantly extend the number and variety of annotation tracks that are publicly available for visualization and analysis from within our site. We have also introduced several usability features including track search and a context-sensitive menu of options available with a right-click anywhere on the Browser's image.

Improving immunoassays based on the analysis of scanning force microscopy images

Scanning force microscopy has been demonstrated to be an effective binding event detection step for immunoassays. In its simplest form--analysing small area images--the detection limit of the scanning force microscopic immunoassay (SFMIA) has been shown to be comparable to existing techniques. In the present work, we have examined how the performance of image analysis-based SFMIA can be improved. Firstly, we have used a surface analysis parameter that increases linearly with the concentration of binding events. This parameter--the surface area ratio--is the ratio of the surface area after antigen binding to the surface area of the original biospecific surface. With this parameter, SFMIA images can be rapidly analysed and converted into assay units. Secondly, we have demonstrated that by using silicon wafer supports that carry fiducial marks we can relocate to very high accuracy onto the biospecific surfaces and identify the changes due to antigen binding. By relocating in this manner the signal to noise ratio of the technique is enhanced. Thirdly, from simulations we have determined the SFM tip size and image area that optimizes the immunoassay sensitivity.

A method for measuring the size distribution of latex particles by scanning force microscopy

A methodology has been developed to accurately determine the size distribution of latex particles using the scanning force microscope (SFM). Unlike other workers, who have generally measured the lateral dimensions of monolayers of latex particles using a global quantification method, we have measured the heights of individual latex particles located at the edges of latex monolayers that were immobilised onto mica substrates. In agreement with other work, we noted that the edges of monolayers of latex particles provided stable and reproducible scanning force imaging. Whilst SFM imaging noise, image processing artifacts, tip/sample forces and variations in the mica substrate are sources of measurement error that should not be overlooked, our experience has been that the variation over time of the sensitivity of the Z actuator is the greatest potential uncertainty in determining the heights of latex particles. The methodology that we used requires frequent calibration of the Z actuator of the SFM, typically before and after two or three images, in order to ensure that the uncertainties in the Z sensitivity are known and minimised. This methodology was developed for an SFM instrument that was equipped with open loop piezoelectric actuators following a careful study of the behaviour of those actuators. Using this methodology, we have measured the size distributions of populations of 300-400 latex particles from each of several different latex samples, with the maximum variation in the Z-actuator calibration experienced during the measurement of a sample being less than 2%, often about 1% and occasionally better still. In so doing, we have demonstrated that SFMs equipped with open loop actuators can be used for high confidence quantitative measurements of step heights.