Measuring relay exchange kinematics in short-track speed skating using a multi-camera network

To support their targeted improvement of the relay exchange, Great Britain Speed Skating required a tool that could be used to advance knowledge on ‘how to execute the relay exchange effectively’. A tool that measures relay exchange kinematics in representative race scenarios, over its entirety, and with an acceptable level of measurement error (± 0.19 m·s-1). A review of existing measurement solutions found that the Olympic Oval (CAN) multi-camera network was the only tool that came close to meeting this criterion. However, while this multi-camera network satisfied the metrics, scenarios, and scope of relay exchange measurement, its ± 1.53 m·s-1 error exceeded the target measurement error. For these reasons, this thesis developed a multicamera network to measure accurate, two-dimensional, relay exchange kinematics. The literature review identified that the accuracy of the National Ice Centre (GBR) multi-camera network was dependent on five sources of measurement error. Accordingly, a series of investigations quantified how these errors propagated, independently, to errors in relay exchange kinematics. In the case where these errors exceeded the target measurement error, additional studies investigated minimising each error. Using this empirically informed measurement workflow, Monte Carlo simulations showed that the multi-camera network’s total error was ± 0.17 m·s-1. This error was within the target measurement error and significantly less than the benchmark Olympic Oval (CAN) multi-camera network. Investigations into the execution of the relay exchange demonstrated how this reduction in error allowed Great Britain Short-Track Speed Skating to advance knowledge on ‘how to execute the relay exchange effectively’. In turn, supporting the team’s targeted improvement of the relay exchange, and ultimately, their aim of delivering medal-winning performances at the Winter Olympic Games

Relay exchanges in elite short track speed skating

In short track speed skating, the relay exchange provides an additional strategic component to races by allowing a team to change the skater involved in the pack race. Typically executed every 1 ½ laps, it is the belief of skaters and coaches that during this period of the race, time can be gained or lost due to the execution of the relay exchange. As such, the aim of this study was to examine the influence of the relay exchange on a team's progression through a 5000 m relay race. Using data collected from three World Cup relay events during the 2012-13 season, the time taken to complete the straight for the scenarios with and without the relay exchange were compared at different skating speeds for the corner exit prior to the straight. Overall, the influence of the relay exchange was found to be dependent on this corner exit speed. At slower corner exit speeds (12.01 - 13.5 m/s), relay exchange straight times were significantly faster than the free skating scenario (P < 0.01). Whilst at faster corner exit speeds (14.01 - 15 m/s), straight times were significantly slower (P < 0.001). The findings of this study suggest that the current norm of executing relay exchanges every 1 ½ laps may not be optimal. Instead, varying the frequency of relay exchange execution throughout the race could allow: (1) time to be gained relative to other teams; and (2) facilitate other race strategies by providing an improved opportunity to overtake

Effective use of storyboarding as a co-design method to enhance power assisted exercise equipment for people with stroke

Power assisted exercise equipment designed to assist multi-directional movements represent an exercise solution for people with stroke. Users identified digitization of the equipment through a new Graphical User Interface (GUI) to display feedback on exercise performance as a development priority. The Medical Device Technology (MDT) framework was adopted to structure the four-stage digitization programme and ensure meaningful user involvement. This paper reports on stage two of the digitization programme, the aim of which was to create a prototype GUI. Storyboarding followed by participatory data analysis was selected as a co-design method to engage professional (n ¼ 6) and expert (n ¼ 8) end users to create artefacts and express preferences relevant to the design of the GUI. Four overarching themes emerged from thematic analysis of the data; (a) aesthetic format, (b) functional features, (c) exercise programme, (d) motivation and reward. The data was crystallized with external sources to generate a design criterion matrix which directed the first iteration of the prototype GUI. Storyboarding with participatory analysis was an effective method for engaging participants in the design of the GUI and associated user experience. This paper represents a novel application of storyboarding to the MDT framework in user centred digital design

Measuring straight time in elite short track speed skating relays

In short track speed skating, the relay exchange provides an additional strategic component to races by allowing a team to change the skater involved in the pack race. It is thought that during this period of the race, time can be gained or lost due to the execution of the relay exchange. However, the only temporal measurement reported in short track speed skating is lap time, of which the relay exchange accounts for less than 30 %. As such, a more appropriate measurement of relay exchange performance might be the time taken to complete the straight where the relay exchange was executed. The aim of this study, therefore, was to validate a method for measuring straight time during elite short track speed skating relays. The proposed method used a single HD camcorder to create virtual timing gates at the start and end of both straights. To validate the method, straight times measured using the single HD camcorder were compared to synchronised cameras located perpendicular to the virtual timing gates. The root mean square error for both near and far straight times was less than the temporal resolution of the camera. In addition, Bland-Altman plots showed that the single HD camcorder method was invariant to race speed. Collectively, these findings suggest that a single HD camcorder does provide a valid method for measuring straight times during elite short track speed skating relays

Evaluating the usability of a co-designed power assisted exercise graphical user interface for people with stroke

Background: Digital advancement of power assisted exercise equipment will advance exercise prescription for people with stroke (PwS). This article reports on the remote usability evaluation of a co-designed graphical user interface (GUI) and denotes an example of how video-conference software can increase reach to participants in the testing of rehabilitation technologies. The aim of this study was to evaluate the usability of two sequential versions of the GUI. Methods: We adopted a mixed methods approach. Ten professional user (PU) (2M/8F) and 10 expert user (EU) participants (2M/8F) were recruited. Data collection included a usability observation, a ‘think aloud’ walk through, task completion, task duration and user satisfaction as indicated by the Post Study System Usability Questionnaire (PSSUQ). Identification of usability issues informed the design of version 2 which included an additional submenu. Descriptive analysis was conducted upon usability issues and number of occurrences detected on both versions of the GUI. Inferential analysis enabled comparison of task duration and PSSUQ data between the PU and EU groups. Results: Analysis of the ‘think aloud’ walkthrough data enabled identification of 22 usability issues on version 1 from a total of 100 usability occurrences. Task completion for all tasks was 100%. Eight usability issues were directly addressed in the development of version 2. Two recurrent and 24 new usability issues were detected in version 2 with a total of 86 usability occurrences. Paired two tailed T-tests on task duration data indicated a significant decrease amongst the EU group for task 1.1 on version 2 (P = 0.03). The mean PSSUQ scores for version 1 was 1.44 (EU group) and 1.63 (PU group) compared with 1.40 (EU group) and 1.41 (PU group) for version 2. Conclusions: The usability evaluation enabled identification of usability issues on version 1 of the GUI which were effectively addressed on the iteration of version 2. Testing of version 2 identified usability issues within the new submenu. Application of multiple usability evaluation methods was effective in identifying and addressing usability issues in the GUI to improve the experience of PAE for PwS. The use of video-conference software to conduct synchronous, remote usability testing is an effective alternative to face to face testing methods

Tactical positioning in short-track speed skating: The utility of race-specific athlete-opponent interactions

In short-track speed skating, tactical positioning is essential for success as the race format (head-to-head) prioritises finishing position over finishing time. At present, our understanding of this phenomenon is based on measuring the similarity between athletes’ intermediate and final rankings. However, as this approach groups athlete performances across races, each lap’s estimate of tactical importance ignores the athlete-opponent interactions specific to each race. Here, we examine the utility of racespecific athlete-opponent interactions for investigating tactical positioning. Using intermediate and final rankings of elite 1,000 m short-track speed skating competitors collected from 2010/11 to 2017/18 (n = 6,196, races = 1,549), we compared the current method to a novel approach that accounted for race-specific athlete-opponent interactions. This approach first applied the current method to each race independently before using these values to form (1) discrete, empirical distributions of each lap’s tactical importance and (2) race-specific tactical positioning sequences. Our results showed that accounting for race-specific athlete-opponent interactions provided a higher measurement granularity (i.e., level of detail) for investigating tactical positioning in short-track speed skating, which better captured the complexity of the phenomenon. We observed 61 different tactical positioning behaviours and 1,269 unique tactical positioning sequences compared to the current approach’s nine-point estimates of tactical positioning importance. For this reason, we recommend that researchers and practitioners account for race-specific athlete-opponent interactions in the future as it offers a deeper understanding of tactical positioning that will enhance both strategic and tactical decisions

Tactical positioning behaviours in short-track speed skating: A static and dynamic sequence analysis

Tactical positioning is essential for success in short-track speed skating as the race format (direct, head-to-head competition over multiple laps) prioritises finishing position over finishing time. Despite this, current research into tactical positioning treats the race’s laps as discrete, independent events. Accordingly, the aggregate metrics used to summarise each lap’s tactical positioning behaviour do not allow us to explore the sequential nature of the data, e.g., Lap 2 occurs after Lap 1 and before Lap 3. Here, we capture the sequential relationships between laps to investigate tactical positioning behaviours in short-track speed skating. Using intermediate and final rankings from 500 m, 1,000 m, and 1,500 m elite short-track races, we analyse whole-race and sub-race race sequences of group and winner tactical positioning behaviours. This approach, combined with a large dataset of races collected over eight seasons of competition (n = 4,135), provides the most rigorous and comprehensive description of tactical positioning behaviours in short-track speed skating to date. Our results quantify the time-evolving complexity of tactical positioning, offer new thoughts on race strategy, and can help practitioners design more representative learning tasks to enhance skill transfer

Do changes in gastro-intestinal blood flow explain high-altitude anorexia?

Background  Gastrointestinal symptoms are common on acute exposure to high-altitude (HA). Underlying mechanisms are not understood, but vascular shunting away from the gut could be responsible. Therefore, blood flow in the superior mesenteric artery (SMA) and hepatic portal vein (HPV) was examined at sea level (SL) and after ascent to 4392 m (HA). Materials and methods  Twelve subjects [eight male, mean age 40 (22–72) years] were studied following an overnight fast and a standard meal. Cross-sectional vessel area and blood velocity were measured by ultrasound, systolic and diastolic flow calculated for the SMA (HR × vessel area × velocity, cm3 min−1) and mean flow for the HPV. Results  All subjects experienced reduced appetite at HA. Blood flow in the SMA and HPV increased following food at SL (mean SMA systolic flow 1024 vs. 3316 cm3 min−1, P < 0·001; HPV 505 vs. 1789, P < 0·001) and at HA (2020 vs. 3767, P < 0·001; HPV 708 vs. 1727, P < 0·001). Pre-prandial flow in the SMA and HPV was significantly increased at HA compared with SL. The changes were due to increased vessel diameter and increased flow velocity. There was no difference in post-prandial flow between SL and HA in the HPV, although the increase in post-prandial flow was greater at SL than HA (254% increase vs. 144%). Conclusions  These results show that resting blood flow in the gastrointestinal tract is increased during exposure to high-altitude hypoxia, and that the vascular response of increased blood flow following food ingestion is maintained. Therefore, reduced flow is unlikely to cause gastrointestinal symptoms and reduced appetite at HA

Lovecraft, decadence, and aestheticism

H. P. Lovecraft (1890–1937) has an enduring influence on Gothic culture across media, and his vision is regarded usually as one of deep pessimism. In his fiction, he reveals the horrifying truth of the insignificance of humanity in the context of an indifferent cosmos. However, Lovecraft was also a committed aesthete, and found profound solace in the appreciation of art, architecture, and literature. This essay explores the relationship of his philosophy and writing to this aestheticism, and especially the influence of Walter Pater on the consolations of art, and its role in creating meaning in the face of a meaningless universe