Effects of acute wearable resistance loading on overground running lower body kinematics.

Field-based sports require athletes to run sub-maximally over significant distances, often while contending with dynamic perturbations to preferred coordination patterns. The ability to adapt movement to maintain performance under such perturbations appears to be trainable through exposure to task variability, which encourages movement variability. The aim of the present study was to investigate the extent to which various wearable resistance loading magnitudes alter coordination and induce movement variability during running. To investigate this, 14 participants (three female and 11 male) performed 10 sub-maximal velocity shuttle runs with either no weight, 1%, 3%, or 5% of body weight attached to the lower limbs. Sagittal plane lower limb joint kinematics from one complete stride cycle in each run were assessed using functional data analysis techniques, both across the participant group and within-individuals. At the group-level, decreases in ankle plantarflexion following toe-off were evident in the 3% and 5% conditions, while increased knee flexion occurred during weight acceptance in the 5% condition compared with unloaded running. At the individual-level, between-run joint angle profiles varied, with six participants exhibiting increased joint angle variability in one or more loading conditions compared with unloaded running. Loading of 5% decreased between-run ankle joint variability among two individuals, likely in accordance with the need to manage increased system load or the novelty of the task. In terms of joint coordination, the most considerable alterations to coordination occurred in the 5% loading condition at the hip-knee joint pair, however, only a minority of participants exhibited this tendency. Coaches should prescribe wearable resistance individually to perturb preferred coordination patterns and encourage movement variability without loading to the extent that movement options become limited.

Combine performance, draft position and playing position are poor predictors of player career outcomes in the Australian Football League.

Physical testing-based draft combines are undertaken across various sporting codes to inform talent selection. To determine the explanatory power of the Australian football league (AFL) draft combine, participants drafted between 1999-2016 (n = 1488) were assessed. Testing performance, draft selection order and playing position, AFL matches played, AFL player ranking points and AFL player rating points were collected as career outcomes. Boosted regression tree analysis revealed that position and draft selection order were the most explanatory variables of career outcomes. Linear modelling based on testing results is able to explain 4% of matches played and 3% of in-game performance measures. Each individual combine test explained <2% of the matches played outcome. Draft selection order demonstrated mixed results for career outcomes relative to playing position. For instance, key forwards and draft selection order were observed as a slight negative relationship using the AFL Player Ranking points career outcome measure. These findings indicate that the AFL draft combine is a poor measure for informing talent selection, thus providing minimal utility for the practices investigated in this study.

Classification of playing position in elite junior Australian football using technical skill indicators.

​In team sport, classifying playing position based on a players' expressed skill sets can provide a guide to talent identification by enabling the recognition of performance attributes relative to playing position. Here, elite junior Australian football players were a priori classified into 1 of 4 common playing positions; forward, midfield, defence, and ruck. Three analysis approaches were used to assess the extent to which 12 in-game skill performance indicators could classify playing position. These were a linear discriminant analysis (LDA), random forest, and a PART decision list. The LDA produced classification accuracy of 56.8%, with class errors ranging from 19.6% (midfielders) to 75.0% (ruck). The random forest model performed at a slightly worse level (51.62%), with class errors ranging from 27.8% (midfielders) to 100% (ruck). The decision list revealed 6 rules capable of classifying playing position at accuracy of 70.1%, with class errors ranging from 14.4% (midfielders) to 100% (ruck). Although the PART decision list produced the greatest relative classification accuracy, the technical skill indicators reported were generally unable to accurately classify players according to their position using the 3 analysis approaches. This player homogeneity may complicate recruitment by constraining talent recruiter's ability to objectively recognise distinctive positional attributes.

Transferring an Analytical Technique from Ecology to the Sport Sciences.

BACKGROUND: Learning transfer is defined as an individual's capability to apply prior learnt perceptual, motor, or conceptual skills to a novel task or performance environment. In the sport sciences, learning transfers have been investigated from an athlete-specific perspective. However, sport scientists should also consider the benefits of cross-disciplinary learning to aid critical thinking and metacognitive skill gained through the interaction with similar quantitative scientific disciplines. OBJECTIVE: Using team sports performance analysis as an example, this study aimed to demonstrate the utility of a common analytical technique in ecology in the sports sciences, namely, nonmetric multidimensional scaling. METHODS: To achieve this aim, three novel research examples using this technique are presented, each of which enables the analysis and visualization of athlete (organism), team (aggregation of organisms), and competition (ecosystem) behaviors. RESULTS: The first example reveals the technical behaviors of Australian Football League Brownlow medalists from the 2001 to 2016 seasons. The second example delineates dissimilarity in higher and lower ranked National Rugby League teams within the 2016 season. Lastly, the third example shows the evolution of game play in the basketball tournaments between the 2004 and 2016 Olympic Games. CONCLUSIONS: In addition to the novel findings of each example, the collective results demonstrate that, by embracing cross-disciplinary learning and drawing upon an analytical technique common to ecology, novel solutions to pertinent research questions within sports performance analysis could be addressed in a practically meaningful way. Cross-disciplinary learning may subsequently assist sport scientists in the analysis and visualization of multivariate datasets.

Non-metric multidimensional performance indicator scaling reveals seasonal and team dissimilarity within the National Rugby League.

OBJECTIVES: Analysing the dissimilarity of seasonal and team profiles within elite sport may reveal the evolutionary dynamics of game-play, while highlighting the similarity of individual team profiles. This study analysed seasonal and team dissimilarity within the National Rugby League (NRL) between the 2005 to 2016 seasons. DESIGN: Longitudinal. METHODS: Total seasonal values for 15 performance indicators were collected for every NRL team over the analysed period (n=190 observations). Non-metric multidimensional scaling was used to reveal seasonal and team dissimilarity. RESULTS: Compared to the 2005 to 2011 seasons, the 2012 to 2016 seasons were in a state of flux, with a relative dissimilarity in the positioning of team profiles on the ordination surface. There was an abrupt change in performance indicator characteristics following the 2012 season, with the 2014 season reflecting a large increase in the total count of 'all run metres' (d=1.21; 90% CI=0.56-1.83), 'kick return metres' (d=2.99; 90% CI=2.12-3.84) and decrease in 'missed tackles' (d=-2.43; 90% CI=-3.19 to -1.64) and 'tackle breaks' (d=-2.41; 90% CI=-3.17 to -1.62). Interpretation of team ordination plots showed that certain teams evolved in (dis)similar ways over the analysed period. CONCLUSIONS: It appears that NRL match-types evolved following the 2012 season and are in a current state of flux. The modification of coaching tactics and rule changes may have contributed to these observations. Coaches could use these results when designing prospective game strategies in the NRL.

Reframing the Food-Biodiversity Challenge.

Given the serious limitations of production-oriented frameworks, we offer here a new conceptual framework for how to analyze the nexus of food security and biodiversity conservation. We introduce four archetypes of social-ecological system states corresponding to win-win (e.g., agroecology), win-lose (e.g., intensive agriculture), lose-win (e.g., fortress conservation), and lose-lose (e.g., degraded landscapes) outcomes for food security and biodiversity conservation. Each archetype is shaped by characteristic external drivers, exhibits characteristic internal social-ecological features, and has characteristic feedbacks that maintain it. This framework shifts the emphasis from focusing on production only to considering social-ecological dynamics, and enables comparison among landscapes. Moreover, examining drivers and feedbacks facilitates the analysis of possible transitions between system states (e.g., from a lose-lose outcome to a more preferred outcome).

The use of player physical and technical skill match activity profiles to predict position in the Australian Football League draft.

This study investigated the extent to which position in the Australian Football League (AFL) national draft is associated with individual game performance metrics. Physical/technical skill performance metrics were collated from all participants in the 2014 national under 18 (U18) championships (18 games) drafted into the AFL (n = 65; 17.8 ± 0.5 y); 232 observations. Players were subdivided into draft position (ranked 1-65) and then draft round (1-4). Here, earlier draft selection (i.e., closer to 1) reflects a more desirable player. Microtechnology and a commercial provider facilitated the quantification of individual game performance metrics (n = 16). Linear mixed models were fitted to data, modelling the extent to which draft position was associated with these metrics. Draft position in the first/second round was negatively associated with "contested possessions" and "contested marks", respectively. Physical performance metrics were positively associated with draft position in these rounds. Correlations weakened for the third/fourth rounds. Contested possessions/marks were associated with an earlier draft selection. Physical performance metrics were associated with a later draft selection. Recruiters change the type of U18 player they draft as the selection pool reduces. juniors with contested skill appear prioritised.

Evolution of game-play in the Australian Football League from 2001 to 2015.

This study investigated the evolution of game-play manifested via team performance indicator characteristics in the Australian Football League (AFL) from the 2001 to 2015 seasons. The mean values for 18 performance indicators were collated for every AFL team over 15-seasons. A multivariate analysis was used to uncover temporal trends in the dataset. Compared to the 2004 season, the 2005 to 2010 seasons were characterised by large growth in the counts of handballs (d = 0.83; 90% CI = 0.22-1.43), disposals (d = 1.24; 90% CI = 0.59-1.87), uncontested possessions (d = 1.37; 90% CI = 0.71-2.01), clangers (d = 2.14; 90% CI = 1.39-2.86) and marks (d = 1.43; 90% CI = 0.76-2.07). Contrastingly, the effective disposal percentage declined rapidly during the same period. The number of inside 50 m counts remained stable throughout the 15-season period. The ordination plot of league-wide performance indicator characteristics illustrated a distinct cluster from the 2001 to 2004 seasons, an abrupt shift from the 2005 to 2009 seasons, and an emergent (re)stabilisation from the 2010 to 2015 seasons. The results demonstrate the synchronous league-wide evolution of game-play in the AFL from the 2001 to 2015 seasons. Amongst other constituents, this evolution likely reflects the introduction of modernised coaching strategies, rule changes and changing perceptions of rule interpretations.

Phenological decoupling of mortality from wave forcing in kelp beds.

Kelps often live in a harsh hydrodynamic environment where wave-driven dislodgement of individuals can alter the biodiversity and functioning of reef systems, and increase production in coastal ecosystems adjacent to reefs. The current paradigm is that winter storms tear kelps from reefs once hydrodynamic forces exceed attachment or tissue strength--a threshold response that implies a pulsed relationship between wave forces and dislodgement. Here, we challenge this understanding by showing how kelp phenology can decouple susceptibility to dislodgement from seasonal patterns in wave forces. We measured kelp dislodgement rates and hydrodynamic forces at nine subtidal reefs over two years (n = 4320 kelps tagged and monitored). Contrary to expectation, we found relatively low and constant dislodgement rates for all reefs (13% +/- 6% [mean per season +/- SD]) in spite of a strong temporal pattern in wave action and extreme water velocities (winter peaks up to 3-4 m/s). A biomechanical model, based on the balance between kelp attachment strength and hydrodynamic drag, demonstrated that severe reduction in individual kelp size toward winter (>50% decrease in biomass for all sites) minimized drag and made the kelps less susceptible to high water velocities, allowing individuals to survive storm velocities over 3-4 m/s. We conclude that the timing of reduced susceptibility to disturbance, through the seasonal reduction of individual kelp biomass that coincides with times of highest water velocities is critical to the dynamics of kelp dislodgement and survival. We propose that phenological processes maintain many kelp beds in a higher degree of population stability and equilibrium with hydrodynamic forces than previously believed.

Predicting playing status in junior Australian Football using physical and anthropometric parameters.

OBJECTIVES: To use physical and anthropometric parameters to predict playing status in junior Australian Football. DESIGN: Cross-sectional observational. METHODS: Participants were recruited from the under 18 competition within the West Australian Football League and classified into two groups; elite (state representative; n=50; 17.9 ± 0.5 y; 184.8 ± 6.9 cm; 80.6 ± 9.4 kg) and sub-elite (non-state representative; n=50; 17.8 ± 0.6 y; 179.8 ± 5.4 cm; 74.4 ± 7.9 kg). Both groups completed physical/anthropometric tests inclusive of a 5 m, 10 m and 20 m sprint, an agility test, stationary vertical jump, dynamic dominant and non-dominant foot vertical jump, 20 m multistage fitness test, standing height and body mass. A multivariate analysis of variance was used to test the main effect of 'status' on the physical/anthropometric parameters, whilst logistic regression models were used to predict playing status using the physical/anthropometric parameters. RESULTS: On average, the elite group were taller, heavier, had a greater stationary vertical jump, dynamic dominant and non-dominant foot vertical jump and higher maximal aerobic capacity as measured by the multistage fitness test (p<0.05). The combination of standing height, dynamic vertical jump non-dominant foot and the 20 m multistage fitness test were the strongest predictors of status (Akaike's Information Criterion=96.35). CONCLUSIONS: Despite mean differences in a number of parameters, the combination of standing height, dynamic vertical jump non-dominant foot and the multistage fitness test were the strongest predictors of status and thus important tests for initially identifying potential talent in junior Australian Football.

Augmenting pancreatic anastomosis during whipple operation with fibrin glue: a beneficial technical modification?

INTRODUCTION: Various techniques have been described to try and reduce the rate of anastomotic leak following pancreaticoduodenectomy, which remains a challenge for pancreatic surgeons worldwide. We outline a technique to reinforce the pancreatic anastomosis with a double layer of fibrin glue between suture lines. METHODS: Our technique for pancreatic anastomosis is described in detail. A review of consecutive pancreaticoduodenectomies by a single surgeon (NAC) since introduction of fibrin glue anastomosis reinforcement was compared with a historical control cohort performed by the same surgeon. RESULTS: Thirty-two consecutive pancreaticoduodenectomies were undertaken between March 2008 and March 2012 by a single surgeon, 30 patients had fibrin glue augmentation of the pancreatico-gastrostomy anastomosis. Median length of stay was 12 days. There were no pancreatic leaks or mortality since adopting fibrin glue for the pancreatic anastomosis; however; this single surgeon series is not large enough to provide statistical evidence of a difference since glue was adopted. DISCUSSION: Our results since the incorporation of this step in pancreaticoduodenectomy are encouraging. Selective use of glue is worthy of consideration in difficult cases, although confirmation of a reduction in pancreatic leak rate is not yet established, and we advocate a multi-institution randomized controlled trial to explore this.

Management of blunt and penetrating biliary tract trauma.

BACKGROUND: Penetrating or blunt injury to the biliary tree remains a rare complication of trauma occurring in 0.1% of trauma admissions. Because of the different presentations, sites of biliary tract injury, and associated organ injury, there are many possible management pathways to be considered. METHODS: A retrospective analysis of prospectively gathered data was performed for all gallbladder and biliary tract injuries presenting to the trauma service or hepatobiliary unit of the Royal Melbourne Hospital between January 1, 1999, and March 30, 2011. RESULTS: There were 33 biliary injuries in 30 patients (0.1%) among 26,014 trauma admissions. Three of the 30 patients (10%) died. Of 10 gallbladder injuries, 8 were managed with cholecystectomy. There were 23 injuries to the biliary tree. Fourteen patients had injuries to the intrahepatic biliary tree of which seven involved segmental ducts. Of these, four segmental duct injuries required hepatic resection or debridement. Nine patients had injury to the extrahepatic biliary tree of which five required T-tube placement ± bilioenteric anastomosis and one a pancreaticoduodenectomy. CONCLUSION: Biliary injury is a rare but important consequence of abdominal trauma, and good outcomes are possible when a major trauma center and hepatopancreaticobiliary service coexist. Cholecystectomy remains the gold standard for gallbladder injury. Drainage with or without endoscopic stenting will resolve the majority of intrahepatic and partial biliary injuries. Hepaticojejunostomy remains the gold standard for complete extrahepatic biliary disruption. Hepatic and pancreatic resection are only required in the circumstances of unreconstructable biliary injury. LEVEL OF EVIDENCE: Therapeutic study, level V.

Management of duodenal adenomatosis in FAP: single centre experience.

Duodenal and ampullary carcinoma in familial adenomatosis (FAP) is the third leading cause of FAP related deaths. Management of this condition is a challenging. The aim of this study was to evaluate the role of multiple targeted endoscopic biopsies and macroscopic appearance as the major determinants for surgical intervention. A secondary aim was to assess histological heterogeneity through comparing endoscopic biopsies and describe the clinical outcomes of our cohort after intervention. We reviewed our FAP surveillance database of 67 patients, between January 1999--June 2011 undergoing upper GI surveillance and where indicated, subsequent surgical intervention. Among 67 patients, 11 underwent surgical resection. Pancreas-preserving duodenectomy was performed in four patients (five procedures), and Whipple's operation in seven patients. The average size of polyps was 43 mm (range 17-65 mm), and the average number of targeted endoscopic biopsies per lesion was 7.5 (range 5-10). Two cases of high-grade (severe) dysplasia were diagnosed on endoscopic biopsies each understaged compared with the subsequent surgical specimen. All carcinomas identified have been resectable with no evidence of local spread or distant metastasis. There was one postoperative death, but no cancer related deaths. We identified both cancers at an early stage and there were no missed or late diagnoses. There have been no recurrences of carcinoma in a more than 7 years follow-up. Due to the heterogeneous nature of these lesions, comprehensive macroscopic assessment should be complemented with multiple targeted biopsies to improve the chance of early detection of advanced lesions.

A two-phase model for smoothly joining disparate growth phases in the macropodid Thylogale billardierii.

Generally, sigmoid curves are used to describe the growth of animals over their lifetime. However, because growth rates often differ over an animal's lifetime a single curve may not accurately capture the growth. Broken-stick models constrained to pass through a common point have been proposed to describe the different growth phases, but these are often unsatisfactory because essentially there are still two functions that describe the lifetime growth. To provide a single, converged model to age animals with disparate growth phases we developed a smoothly joining two-phase nonlinear function (SJ2P), tailored to provide a more accurate description of lifetime growth of the macropod, the Tasmanian pademelon Thylogale billardierii. The model consists of the Verhulst logistic function, which describes pouch-phase growth--joining smoothly to the Brody function, which describes post-pouch growth. Results from the model demonstrate that male pademelons grew faster and bigger than females. Our approach provides a practical means of ageing wild pademelons for life history studies but given the high variability of the data used to parametrise the second growth phase of the model, the accuracy of ageing of post-weaned animals is low: accuracy might be improved with collection of longitudinal growth data. This study provides a unique, first robust method that can be used to characterise growth over the lifespan of pademelons. The development of this method is relevant to collecting age-specific vital rates from commonly used wildlife management practices to provide crucial insights into the demographic behaviour of animal populations.

Two decades of percutaneous transjejunal biliary intervention for benign biliary disease: a review of the intervention nature and complications.

OBJECTIVE: To assess outcomes of percutaneous transjejunal biliary intervention (PTJBI) in terms of success and effectiveness in patients with a Roux-en-Y hepaticojejunostomy for benign biliary strictures and stones. METHODS: Clinical and radiographic records of 63 patients with a Roux-en-Y choledochojejunostomy or hepaticojejunostomy for benign disease who underwent at least one PTJBI between 1986 and 2007 were reviewed. Effectiveness was determined by successful access rate, rates of stricture dilatation and/or stone extraction, morbidity, complications and hospitalisation. RESULTS: PTJBI was attempted 494 times. Successful access to the Roux-en-Y was accomplished in 93% of interventions. After access to the Roux-en-Y was granted, all strictures were effectively dilated. Ninety-seven percent of extraction attempts of intrahepatic calculi were successful. The median number of interventions per patient was five. The median interval between interventions was 51.5 weeks (range 2.7-1,279.6 weeks). The early complication rate was 3%. Morbidity, measured in terms of cholangitis episodes was 14%, in 25 out of 63 patients. Mean hospitalisation was 4.1 nights per year. CONCLUSION: PTJBI is safe and effective in treating benign biliary strictures and/or calculi. High success rates and short hospitalisation periods, together with few complications make it a well-accepted and integral part of managing complex biliary problems.

Lobar and segmental liver atrophy associated with hilar cholangiocarcinoma and the impact of hilar biliary anatomical variants: a pictorial essay.

The radiological features of lobar and segmental liver atrophy and compensatory hypertrophy associated with biliary obstruction are important to recognise for diagnostic and therapeutic reasons. Atrophied lobes/segments reduce in volume and usually contain crowded dilated bile ducts extending close to the liver surface. There is often a "step" in the liver contour between the atrophied and non-atrophied parts. Hypertrophied right lobe or segments enlarge and show a prominently convex or "bulbous" visceral surface. The atrophied liver parenchyma may show lower attenuation on pre-contrast computed tomography (CT) and CT intravenous cholangiography (CT-IVC) and lower signal intensity on T1-weighted magnetic resonance imaging (MRI). Hilar biliary anatomical variants can have an impact on the patterns of lobar/segmental atrophy, as the cause of obstruction (e.g. cholangiocarcinoma) often commences in one branch, leading to atrophy in that drainage region before progressing to complete biliary obstruction and jaundice. Such variants are common and can result in unusual but explainable patterns of atrophy and hypertrophy. Examples of changes seen with and without hilar variants are presented that illustrate the radiological features of atrophy/hypertrophy.

Radical prostatectomy: a systematic review of the impact of hospital and surgeon volume on patient outcome.

BACKGROUND: To assess the impact of hospital and surgeon volume on mortality, morbidity, length of hospital stay and costs of radical prostatectomy (RP). METHODS: This systematic review identified relevant studies published between 1997 and June 2007. Inclusion of papers was established through application of a predetermined protocol, independent assessment by two reviewers, and a final consensus decision. RESULTS: Compared with low volume hospitals, the included studies showed high volume hospitals demonstrated lower rates of mortality, postoperative complications and readmissions, and lower overall hospital costs. High volume surgeons similarly showed lower rates of postoperative complications and shorter length of stay compared with low volume surgeons, but no difference in mortality. CONCLUSIONS: From the literature obtained, patients undergoing RP performed by high volume providers may have better outcomes compared to low volume providers; however, any move to centralize RP must be further evaluated.

Centralization and the relationship between volume and outcome in knee arthroplasty procedures.

BACKGROUND: Centralization aims to reduce adverse patient outcomes by concentrating complex surgical procedures in specified hospitals. OBJECTIVES: This review assessed the efficacy of centralization for knee arthroplasty by examining the relationship between hospital and surgeon volume and patient outcomes. DATA SOURCES AND REVIEW METHODS: The systematic review identified studies using multiple databases, including Medline and Embase. Two independent researchers ensured studies met the inclusion criteria. Morbidity, mortality, length of stay, financial outcomes and statistical rigour were examined. Correlations between volume and outcome were reported. RESULTS: Twelve primary knee arthroplasty studies examined hospital volume, which was significantly associated with decreased morbidity (five of seven studies), mortality (two of five studies) and length of stay (two of three studies). Three primary knee arthroplasty studies examined surgeon volume, which was significantly associated with decreased morbidity (two of three studies), mortality (zero of two studies) and length of stay (one of one study). Two revision knee arthroplasty studies examined hospital volume. One study examined but did not test for significance between hospital volume and patient morbidity; both studies examined volume and patient mortality reporting inconclusive results; and one study reported no significant association between volume and length of stay. None of the revision knee arthroplasty studies examined surgeon volume. CONCLUSIONS: Significant associations between increased hospital and surgeon volume and improved patient outcomes were reported. However, when these results were separated by arthroplasty type, the association appeared tenuous. Judgements regarding centralization of knee arthroplasty should be made with caution until further evidence is published.