A KINEMATIC ANALYSIS OF FINGER MOTION IN ARCHERY

This paper examines finger motion during the bow string release in archery. METHOD: Fifty-six shots from one athlete were captured with an infrared motion tracking system. Kinematics for index, third and ring fingers were calculated. Two different kinematic variables were defined, related to the proximal interphalangeal joint (PIP) of the third finger: maximum angular velocity (MAX) and minimum angular velocity (MIN). For statistical analysis shots were separated into two groups (very good shots: shots which hit the innermost score area and bad shots: score of 8 or less; shots which achieved a nine or a ten were excluded). A Mann-Whitney test was used. RESULTS: No significant differences were found in the variables MAX and MIN between very good and bad shots (p > 0.05). CONCLUSION: Findings in this study show that there are no significant differences in angular velocity (related to the PIP joint) between very good and bad shots, but that reproducibility of kinematic characteristics are possible crucial factors in archer’s performance

A KINEMATIC ANALYSIS OF THE NAERYO-CHAGI TECHNIQUE IN TAEKWONDO

The purpose of this study was to investigate the influence of selected kinematic parameters on the performance of the naeryo-chagi technique in taekwondo. Performance was quantified by the vertical velocity of the ankle at initial target contact (VIMP). METHOD: A sample of 19 competitive taekwondo athletes (17 males and 2 females) aged from 17 to 30 years (mean age = 19 ± 4), who were able to accomplish a correct naeryo-chagi technique, participated in this study. After warm up, participants were asked to perform several series of five naeryo-chagi kicks with their front leg at a kicking pad which was mounted on a frame at chin height. For data acquisition a motion tracking system comprising eight infrared cameras and a force plate were used. Only that series, which included the trial with the highest ankle velocity at initial target contact, was further processed. RESULTS: Significant differences between the best and worst performed kick of each athlete (p = 0.025) were found for the extension of the hip joint during the pull down phase (EHIP). No significant differences were found for the maximum ankle velocity during the strike out phase (AVSO; p = 0.28). Considering the best trials of each athlete only, Pearson correlation between EHIP and VIMP was significant (r = 0.542; p = 0.017), that between AVSO and VIMP was not (r = 0.354, p = 0.137). CONCLUSION: The magnitude of change of the hip flexion angle during the pull down movement seems to be an important factor for performing a kick featuring high velocity at initial target contact

Reliability of walking and stair climbing kinematics in a young obese population using a standard kinematic and the CGM2 model

Background: Recently, the successor of the Conventional Gait Model, the CGM2 was introduced. Even though achievable reliability of gait kinematics is a well-assessed topic in gait analysis for several models, information about reliability in difficult study samples with high amount of subcutaneous fat is scarce and to date, not available for the CGM2. Therefore, this study evaluated the test–retest reliability of the CGM2 model for difficult data with high amount of soft tissue artifacts. Research question: What is the test–retest reliability of the CGM2 during level walking and stair climbing in a young obese population? Is there a clinically relevant difference in reliability between a standard direct kinematic model and the CGM2? Methods: A retrospective test–retest dataset from eight male and two female volunteers was used. It comprised standard 3D gait analysis data of three walking conditions: level walking, stair ascent and descent. To quantify test–retest reliability the Standard Error of Measurement (SEM) was calculated for each kinematic waveform for a direct kinematic model (Cleveland clinic marker set) and the CGM2. Results: Both models showed an acceptable level of test–retest reliability in all three walking conditions. However, SEM ranged between two and five degrees () for both models and, thus, needs consideration during interpretation. The choice of model did not affect reliability considerably. Differences in SEM between stair climbing and level walking were small and not clinically relevant (1°). Significance: Results showed an acceptable level of reliability and only small differences between the models. It is noteworthy, that the SEM was increased during the first half of swing in all walking conditions. This might be attributed to increased variability resulting for example from inaccurate knee and ankle axis definitions or increased variability in the gait pattern and needs to be considered during data interpretation

Eine kinematische Analyse der Fingerbewegung beim Lösen der Sehne im Recurve-Bogensport

Ziel dieser Arbeit ist die Erfassung kinematischer Daten der Fingerbewegungen und der Bogensehnenbewegung beim Lösen der Sehne im Recurvebogensport. METHODIK: Zur Erfassung der kinematischen Daten wurde ein Infrarotkamerasystem der Firma Vicon verwendet. Untersucht wurde ein B-Nationalkader Schütze mit internationaler Wettkampferfahrung (WM Teilnahme 2007). 56 ausgewertete Schüsse wurden in zwei Gruppen eingeteilt: gute und schlechte Schüsse. Weiters wurden fünf kinematische Kenngrößen definiert und für beide Gruppen mittels eines Student´s t-Test für unabhängige Stichproben statistisch überprüft. Folgende fünf Kenngrößen wurden bestimmt: Minimumwert der Winkelgeschwindigkeit (MIN) beim Lösen der Bogensehne, Maximumwert der Winkelgeschwindigkeit (MAX) beim Lösen der Bogensehne, Zeitspanne (P-P) zwischen dem Auftreten von MIN und MAX, Vergleich (VL) der direkten Vektorenweglänge der Bogensehne mit der tatsächlichen und die maximale Sehnenseitauslenkung (hg). ERGEBNISSE: Hinsichtlich der fünf kinematischen Kenngrößen wurde ein signifikanter Unterschied in der Kenngröße hg (p=0,003*) gefunden. Als gute quantifizierte Schüsse zeigten eine größere Auslenkung der Bogensehne zur Seite auf (Mittelwert = 24,31 ± 0,7 mm), als Schüsse, welche als schlecht quantifiziert wurden (Mittelwert = 23,42 ± 0,8 mm). Bei allen weiteren Kenngrößen fand sich kein signifikanter Unterschied in den Gruppen.The aim of this paper is a three-dimensional kinematic analysis of finger and bowstring movement during bowstring release. METHOD: A top athlete of the Austrian B-national Team was investigated. A sum of 90 shots was captured. Fifty-six shots could be used for further analysis. The shots were, due to their achieved score, divided into two groups: good and bad shots. Furthermore, there were five different kinematic variables defined (related to the finger middle joint of the third finger): maximum angular Velocity (MAX), minimum angular velocity (MIN), period between MAX and MIN (P-P), maximum bowstring side-movement (hg) and the comparison (VL) of the distance between the direct vector length and the real vector length of the bowstring. A Student´s t-Test was calculated to check if there are any significant differences between the two groups in the kinematic variables. RESULTS: Significant differences were only found in the variable hg (p=0,003*). Shots out of the “good” group showed larger bowstring side-movement (mean hg = 24,31 ± 0,7 mm) than shots out of the “bad” group (mean hg = 23,42 ± 0,8 mm). All other variables showed no significant differences

Trustworthy Visual Analytics in Clinical Gait Analysis: A Case Study for Patients with Cerebral Palsy

Three-dimensional clinical gait analysis is essential for selecting optimal treatment interventions for patients with cerebral palsy (CP), but generates a large amount of time series data. For the automated analysis of these data, machine learning approaches yield promising results. However, due to their black-box nature, such approaches are often mistrusted by clinicians. We propose gaitXplorer, a visual analytics approach for the classification of CP-related gait patterns that integrates Grad-CAM, a well-established explainable artificial intelligence algorithm, for explanations of machine learning classifications. Regions of high relevance for classification are highlighted in the interactive visual interface. The approach is evaluated in a case study with two clinical gait experts. They inspected the explanations for a sample of eight patients using the visual interface and expressed which relevance scores they found trustworthy and which they found suspicious. Overall, the clinicians gave positive feedback on the approach as it allowed them a better understanding of which regions in the data were relevant for the classification.Comment: 7 pages, 4 figures; supplemental material 9 pages, 8 figures; to be published in the proceedings of the 2022 IEEE Workshop on TRust and EXpertise in Visual Analytics (TREX

Present knowledge of distribution of Tandonia budapestensis (Hazay, 1881) in the Czech and Slovak Republics (Gastropoda: Milacidae)

All published and known unpublished data on Tandonia budapestensis (Hazay, 1881) from the territory of the Czech and Slovak Republics are summarised. This species occurs rarely in both states in altitudes up to ca. 420 m. and is closely bound to anthropogenous habitats