The observational analysis of elite coaches within youth soccer: The importance of performance analysis

The study investigated the observational capabilities of experienced elite coaches whilst focusing upon soccer specific actions and playing positions within elite youth soccer. Six soccer coaches assessed the performances of 10 youth soccer players (across 8 matches) on their short/long passing, tackling, shooting, heading and dribbling. Analysis was undertaken on an overall, quality and positional grouping basis. Mean observational accuracy was 38.8%, with successful shooting (78.6%) and passing (29.9%) illustrating the range. The limited effective observation of dribbling (37.2%), often considered a separating factor within talent identification, highlights the need for objective measures to aid such processes. Positional grouping analysis elicited 20% more effective observation for unsuccessful compared with successful actions. The poor level of observational accuracy identified herein has significant implications on talent identification assessments devoid of post-performance analyses. The findings reinforce the importance of performance analysis in the provision of highly accurate and comprehensive augmented feedback within the coaching process

Track cycling: An analysis of the pacing strategies employed during the devil elimination race

This study aimed to provide a description of the pacing requirements of the track cycling Elimination race, and to identify effective pacing strategies to maximise overall Omnium medal opportunity. Six male, and six female elite competitive races were investigated using half-lap split times. Selected dependant variables were; mean speed and variation in speed. Spearman’s Rho correlations were used to test patterns between dependant variables and the final finishing position of riders. One-way ANOVAs were also applied to test for differences in dependant variables, between successful (top 6 finishers) and unsuccessful groups (7th-12th). Pacing patterns of the men's and women's races were complex, but followed an overall positive and variable pacing pattern, with men's race quarter speeds of 52.8km/h (±1.9), 52.1km/h (±2.1), 51.1km/h (±2.2), and 49.5km/h (±5.5). In general, differences in pacing strategy were not found to significantly influence the success of riders unless employed late in the race. Results are discussed for the application and the development of effective elimination race strategies and tactics

The importance of perturbations in elite squash: An analysis of their ability to successfully predict rally outcome

This is the authors' post-print of an article published in International Journal of Performance Analysis in Sport, 2014.This study investigated the presence of perturbations within elite squash through the analysis of critical incidents responsible for successful rally outcome

A submersible battery-powered flow injection (FI) sensor for the determination of nitrate in estuarine and coastal waters

The design, construction and performance of a remotely deployed submersible flow injection-based nutrient (total oxidized nitrogen) sensor are described. The sensor featured a custom-built microcomputer and a solid-state, flow-through spectrophotometric detector, and the derivatization chemistry was based on in-line coppercadmium reduction of nitrate to nitrite, and diazotization with N1NED and sulphanilamide. The limit of detection was 0.0014 mg l-1 NO3-N and the linear range was 0.0014- 0.77 mg l-1 with a 260 μl sample volume and a 20 mm path length flow cell. Results from submersed deployments in the Tamar estuary and North Sea are also reported

Swarming behaviour in elite race bunch cycling: a case study

The current study undertook a dynamical systems analysis of race bunch cycling, considering the 'sports contest' as a dynamical, self organising system (McGarry et al., 2002). Data from one international track racing event was used to analyse a potential non-linear aggregation theory of 'swarming' in the 'points race', with two objectives; 1) To identify a race profile of a basic swarm mentality within the points race; 2) To identify system stability and the possible perturbation of stability in relation to successful and unsuccessful breakaways. Stability was based upon a 'normal' profile of race behaviours, measured by three separate dependent measures, namely; Absolute Difference, Rate of Change and Phase Duration. Results showed; 1) The points race exhibits the quintessential 'attract and repel' elements that characterise the swarm mentality 2) One-way ANOVA revealed that breakaways of both successful (3.3±1.2 half laps) and unsuccessful (3.1±1.5 half laps) conditions tend to differ from the race 'norm' (2.1±1.3 half laps) in terms of phase duration (F(2, 228)=18.4, P<0.05), suggesting that breakaways perturb the system through longer attract and repel phases. Results are discussed in relation to the current and future effectiveness of describing race bunch cycling as a dynamical system

The reliability of Functional Movement Screening (FMS) and in-season changes in physical function and performance among elite rugby league players

This is the authors' PDF post-print of an article accepted for publication in the Journal of Strenght and Conditioning Research. The definitive version is available at http://journals.lww.com/nsca-jscrThis is not the published version. The final version of the article is available at doi 10.1519/JSC.0000000000000270Functional Movement Screening (FMS) comprises seven tests that assess fundamental movement characteristics of athletes. However, the reliability of the FMS protocol and its sensitivity to changes in physical performance has not been appropriately investigated. Accordingly, this study aimed to assess the real-time reliability of the FMS protocol and to establish changes in both FMS and tests of physical performance throughout a season. The reliability of the FMS components (12 in total) were assessed via a non-parametric statistical approach, based on two trials, separated by one week. Score on the FMS, strength (3 RM full squat, 1 RM bench press), running speed (10 & 40 m) and jump height of 12 elite male under-19 rugby league players was monitored at pre-, mid- and late-season periods. There was no bias found between trials for the FMS, with the majority of components reaching 100% ‘perfect agreement’. There were no effects of season stage on any of the FMS components; however, an improvement in every performance test was apparent between the pre- and both mid- and late-season periods. Our findings demonstrate that the FMS can be reliably administered to elite rugby league players but question its sensitivity to systematic changes in athletic performance

Analytical Intercomparison Between Flow Injection-Chemiluminescence and Flow Injection-Spectrophotometry for the Determination of Picomolar Concentrations of Iron in Seawater

A lab- and ship-based analytical intercomparison of two flow injection methods for the determination of iron in seawater was conducted, using three different sets of seawater samples collected from the Southern Ocean and South Atlantic. In one exercise, iron was determined in three different size-fractions (\u3c 0.03 &μm, \u3c 0.4 μm, and unfiltered) in an effort to better characterize the operational nature of each analytical technique with respect to filter size. Measured Fe concentrations were in the range 0.19 to 1.19 nM using flow injection with luminol chemiluminescence detection (FI-CL), and 0.07 to 1.54 nM using flow injection with catalytic spectrophotometric detection with N, N-dimethyl-p-phenylenediamine dihydrochloride (FI-DPD). The arithmetic mean for the FI-CL method was higher (by 0.09 nM) than the FI-DPD method for dissolved (\u3c 0.4 μm) Fe, a difference that is comparable to the analytical blanks, which were as high as 0.13 nM ( CL) and 0.09 nM (DPD). There was generally good agreement between the FI-CL determinations for the \u3c 0.03 μm size fraction and the FI-DPD determinations for the \u3c 0.4 μm size fraction in freshly collected samples. Differences in total-dissolvable ( unfiltered) Fe concentrations determined by the two FI methods were more variable, reflecting the added complexity associated with the analysis of partially digested particulate material in these samples. Overall, however, the FI-CL determinations were significantly (P = 0.05) lower than the FI-DPD determinations for the unfiltered samples. Our results suggest that the observed, systematic inter-method differences reflect measurement of different physicochemical fractions of Fe present in seawater, such that colloidal and/or organic iron species are better determined by the FI-CL method than the FI-DPD method. This idea is supported by our observation that inter-method differences were largest for freshly collected acidified seawater, which suggests extended storage (\u3e6 months) of acidified samples as a possible protocol for the determination of dissolved iron in seawater

The influences of rugby spin pass technique on movement time, ball velocity and passing accuracy

This is an Accepted Manuscript of an article published by Taylor & Francis in International Journal of Performance Analysis in Sport in April 2014, available online: https://doi.org/10.1080/24748668.2014.11868722The success of a rugby spin pass is determined by the speed of the passing movement and the resultant velocity, distance and accuracy of the ball flight. The present study investigated 900 dominant and 900 non-dominant hand spin passes at three randomised target distances (4, 8 and 12 m), whilst players ran between 60 and 80% of their maximum speed. Two distinct types of spin pass technique were compared. One involved the player lowering their body height (‘body drop’) then raising it again prior to ball release, and the other, players maintained a more upright body position and incorporated greater arm movement. The current study assessed performance measures (velocity, spin, timing, accuracy) of the two previously identified passing techniques made from the players’ dominant and non-dominant hands. The percentage of passes which included a ‘body drop’ phase rose linearly with pass distance. The ‘body drop’ technique resulted in higher ball velocities and improved accuracy from both the dominant and non-dominant passing hands. In comparison, the more upright passing technique resulted in a faster passing movement, but was compromised by lower ball velocity and accuracy. The findings provide an understanding of how different spin pass techniques affect the mechanics of ball flight and performance

THE EFFECT OF BUNGEE TENSION ON POWER PROFILING IN KAYAK ERGOMETRY

In water sports, where accurate biomechanical measurement in situ is difficult, ergometers are frequently used to test athletes. Many kayak ergometer designs involve a bungee to assist in returning the athlete/paddle to the correct position for the next stroke. The study’s aim was to investigate the effect of bungee tension on the ergometermeasured maximal power-velocity profile of three experienced male kayak athletes. Bungee tension influenced the power-velocity profile, reducing peak power measured by up to 328.4 W from optimal to least optimal tension. Athlete’s anecdotally preferred feel tensions may be optimal, thus these tensions should be considered in investigating power-related factors

A longitudinal analysis of performance, growth and maturation in youth rugby league players: Implications for talent identification and development

This study monitored a cohort of youth rugby league players from one professional club in England, across three competitive seasons (under-15 to under-17 age group). The aims were to establish which dimensions of growth and performance characterized players who were either coach-selected or unselected each season and to evaluate annual developments in growth and performance. It was also necessary to establish the credibility of various measurement techniques that are implicated in the talent identification process. In the assessment of sprint performance, GPS measurements systematically underestimated both distance and timing gate speed but can be used to reliably evaluate sprint performance, particularly for measurements of peak speed (95% Limits of Agreement (LoA) = 0.00 ± 0.8 km·h-1; CV = 0.78%). Using a larger sample of youth team sport players (n = 60), multiple linear regression analysis, incorporating mean and peak GPS speeds as predictors of timing gate speed, yielded a prediction model that was able to provide a valid alternative to timing gates in the assessment of sprint performance over 30 m. With regards to the reliability of assessments of sport-specific skill in youth rugby league players, no comparisons met the pre-determined analytical goal of ‘perfect agreement’, meaning that up to 56% of players’ skill could be misinterpreted. The credibility of such assessments should be questioned and alternative tests considered. In the period between the under-15 and under-16 group, there were large annual increments in speed (5.02 Δ%), force (13.82 Δ%) and power (19.85 Δ%) generated over 10 m sprint intervals and predicted vertical jumping power (13.02 Δ%), with concomitant developments in body mass (5.14 Δ%), lean body mass (3.20 Δ%) and predicted muscle of the quadriceps (10.12 Δ%). A discriminant function analysis also highlighted 30 m force and 10 m acceleration as significant predictors of selected players in the under-15 group and under-16 group, explaining 47.3% and 40.7% of the between-group variance, respectively – which was the case independent of age at peak maturity. However, there were 5 no differences between selected and unselected players in the under-17 group. During match time, there were differences between selected (57.1 ± 11.9 min) and unselected (44.1 ± 12.3 min) players for average playing interval in the under-16 group. In turn, selected players covered more total distance (5181.0 ± 1063.5 m c.f. 3942.6 ± 1108.6 m, respectively; P = 0.012) and high intensity distance (1808.8 ± 369.3 m c.f. 1380.5 ± 367.7 m, respectively; P = 0.011) than unselected players. When age at peak height velocity (PHV) was statistically controlled, only distance in zone 3 and summated-HR remained higher in the selected players of the under-16 group. Conversely, higher values amongst the unselected under-16 players for total and relative distance in zone 4, 5 and high intensity were revealed. There was a relationship in the under-15 group (R = 0.702, P < 0.001), under-16 group (R = 0.607, P < 0.001) and under-17 group (R = 0.671, P < 0.006) between the number of successful ball carries and 10 m sprinting force, thus supporting the use of 10 m sprinting force as a predictor of match performance. The relationship (r = 0.51, P = 0.044) between aerobic capacity and HIT·min-1 in the under-17 group also provides preliminary evidence of aerobic endurance as a potential predictor of match running intensity. It was concluded that players who are coach-selected are not characterized by match related performance variables but are offered greater match exposure during the under-16 age group, resulting in larger running distances. Unselected players are unrewarded for higher intensity running during matches when maturational age is statistically controlled and are also equally effective in regard to tackling and ball carrying outcomes. These results collectively indicate the inability of match performance measurements to contribute to talent identification processes in players of this type. The changes in growth and performance should be used to guide talent development practices of rugby league coaches. In particular, the assessment of force (i.e. the product of acceleration and body mass) should be considered as an important factor in differentiating between higher and lower ability players, as well as relating to match performance