icSPORTS 2016 Abstracts

Area 1 - Computer Systems in Sports
Full Papers Short Papers
Area 2 - Health, Sports Performance and Support Technology
Full Papers Short Papers
Area 3 - Signal Processing and Motor Behavior
Full Papers Short Papers
Area 4 - Sports Medicine and Support Technology
Short Papers

Area 1 - Computer Systems in Sports

Full Papers
Paper Nr: 16
Title:

An Intelligent System for Motor Style Assessment and Training from Inertial Sensor Data in Intermediate Level Ski Jumping
Authors:

Heike Brock and Yuji Ohgi
Abstract: In this research we developed a wearable, augmented motion feedback system for ubiquitous training and motion assessment in mid-level ski jumping. Ski jump motion data captured with a set of inertial sensors were first transformed into meaningful kinematic motion information using an extensive processing system. Next, derived segment orientations, joint positions and joint angles were used to build and train motion knowledge on the base of the sport’s common style and judging criteria. This intelligent machine knowledge was then applied to identify specific style information within incoming motion data that could be provided to the athlete as augmented motion feedback via a mobile training application. System validations on a set of test jumping data showed that style errors could be recognized and displayed well by the implemented system. We therefore believe the system to be suitable for the provision of kinematic motion feedback that could not be obtained without an extensive training support environment otherwise. Adding a real-time environment for athlete-system communication, this could lead to the creation of an ubiquitous training support application in future.
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Paper Nr: 39
Title:

Road Cycling Climbs Made Speedier by Personalized Pacing Strategies
Authors:

Stefan Wolf, Raphael Bertschinger and Dietmar Saupe
Abstract: Lately, modeling and optimizing endurance performance has become popular. Optimal strategies have been calculated for running as well as for cycling. Since most of these studies are of theoretical nature, we performed a series of experiments to determine whether race performance can actually be improved using mathematical optimization in a realistic scenario. The optimal strategy was based on the equations of motion for cycling and an individual critical power model for each rider. Constant visual feedback based on the calculated strategy was given to the rider while performing a real world climb on a bike simulator in the laboratory. The aim of this study was to determine whether these strategies are feasible and effective. The results showed that feedback in general and the optimal strategy feedback in particular led to a significant improvement. The total race times decreased between 0.8% and 3.2% employing optimal strategy feedback compared to self paced rides.
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Paper Nr: 44
Title:

A Portable, Inexpensive Point-Tracking System for Validation of Wearable Biomechanics Sensors
Authors:

G. P. Bailey and R. K. Harle
Abstract: In-field validation of the accuracy of wearable sensors is desirable since algorithms that perform well in a laboratory setting may not perform as well in real-world use. However, the use cases can be challenging. For example, a foot worn wearable designed to measure foot trajectory should expect to be used in a variety of scenarios ranging from straightforward (running track) to challenging (a woodland area with many undulations). Typically the more challenging the scenario the more difficult it is to get ground truth with conventional systems. We describe a low-cost, highly-portable, point tracking system that can be used where space and infrastructure is limited. The system is built around a pair of commodity video cameras in a stereo setup. We demonstrate how to configure the cameras, a novel technique to approximate shutter synchronisation to sub-frame interval, and we benchmark the system indoors against gold-standard motion capture systems. For a runner 3 m from the cameras were able to recover their foot trajectory with a mean spatial deviation of 1.7±1.1 cm.
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Paper Nr: 53
Title:

Experimental Investigation of the Usfulness of Bracelet Trackers in Sports and Health Monitoring - Critical Evaluation of a New Handheld Activity Monitoring Device Class
Authors:

Hans Weghorn
Abstract: In professional sports and medicine, the use of electronic devices for activity monitoring and controlled exercising is commonly established since many decades. Due to miniaturization of computer electronics, sports and health devices became popular for non-elite sports users during the last twenty years, many of these in the appearance of watch-like systems, e.g. as running computers or as versatile heart rate monitors. Technologically based on such devices and since few time, various vendors in the sports and health field started to offer bracelet-like systems, while making the customers believe that the continuous use of such devices in daily life can be considered even more fashionable and helpful. This paper compares the new wristband device generation with the established, well-working sports watches. Significant findings about the sensor quality together with observation of the enforced Internet-based user handling yield a rather critical reflection about the usefulness of the this new device class for sports and health activity tracking.
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Paper Nr: 54
Title:

Modeling V?O2 and V?CO2 with Hammerstein-Wiener Models
Authors:

Alexander Artiga Gonzalez, Raphael Bertschinger and Dietmar Saupe
Abstract: V̇O₂ and V̇CO₂ measurements are central to methods for assessment of physical fitness and endurance capabilities in athletes. As measuring V̇O₂ and V̇CO₂ is difficult outside a lab, models with good prediction properties are necessary for online analysis and modeling in the field. Easier to measure are heart rate and during cycling also power. Thus, the here described models are based on either one of them or both. It is commonly accepted that the relationship between power and V̇O₂, V̇CO₂ and heart rate can be described by a linear and a nonlinear component. The latter describes a drift over time without increase in workload. Thus, block-structured systems such as Hammerstein-Wiener models with linear and nonlinear elements can be employed for modeling and prediction. Modeling and prediction power of these models is compared with a dynamic model based on physiological evidence. Our findings show that the simpler Hammerstein-Wiener model performs slightly better for both modeling and prediction with the advantage of being easier to estimate and evaluate. Overall, both models performed with errors smaller than the range of the natural variability of the modeled quantities. Thus, such models allow for applications in the field where V̇O₂ and V̇CO₂ cannot be measured.
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Paper Nr: 59
Title:

Space Sports – Sailing in Space
Authors:

Maria Sundin, Lars Larsson and Christian Finnsgård
Abstract: Titan is the largest moon of Saturn, and apart from the Earth it is the only body in our solar system where a liquid exists on the surface. Within the last ten years a system of lakes and rivers have been discovered. The climate and seasonal cycles of Titan are still not very well known, but the composition and pressure are fairly well established. Perhaps in the future boats will sail the lakes of Titan for research purposes or even sport. The purpose of this paper is to give an overview of the concept of space sports, the conditions of Titan and to calculate important parameters of sailing such as floatability, stability, hull resistance and sail forces. This paper shows that if a sailing yacht on Titan will have twice as large displacement as on Earth, it will be 2.6 times less stable for the same beam. Since friction will be smaller, it will be faster than on Earth at low speed, but significantly slower at high speeds due to the wave generation. The same sail area is required to get the same sail forces if the average wind is 3 m/s, while a 9 times larger sail area is required for if the wind speed is only 1 m/s.
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Paper Nr: 62
Title:

Development of Computer System for Digital Measurement of Human Body: Initial Findings
Authors:

Darko Katović, Igor Gruić, Anita Bušić, Tomislav Bronzin, Krešimir Pažin, Filip Bolčević, Vladimir Medved and Marjeta Mišigoj-Duraković
Abstract: Background: Microsoft Kinect is used in the field of anthropometry (Sameijma et al., 2012; Xu et al., 2013; Clarkson et al., 2016; Zhang et al., 2015), gait analysis (Springer & Seligman, 2016; Pfister et al., 2014; Motiian et al., 2015; Prochazka et al., 2015; Cippitelli et al., 2015), motor performance (Lim et al., 2015; Sevick et al., 2016; Taha et. al., 2016), posture/balance evaluation (Dutta et al., 2014; Metiplay et al., 2013; Oh et al., 2014; Saenz-de-Urturi & Garcia-Zapirain Soto, 2016) and rehabilitation (Galna et al., 2014; Mobini et al., 2015; De Rosario et al., 2014; Shapi’i et al., 2015). Reliability of instruments in clinical and sport application differ, therefore the goal of this research was to initially determine the protocol of validation of a new measuring instrument for digital measurement of anthropometric dimensions of the body (structural and metric). Reliability of results in this paper was tested on three classically and digitally measured anthropometric variables, i.e. height, left forearm length and left lower leg length. Methods: Male and female employees of the Technology Park Zagreb (N=52) volunteered for this research. Subjects were wearing their everyday clothes. Among 471 assessed variables (3 + ((26 * 6)) * 3) three variables from a set of classically measured anthropometric dimensions were extracted - height, length of left forearm and length of left lower leg. Classical measurements were conducted through standard IBP protocols, a Standardized protocol for digital measurement (DM-I) was produced. Data were analyzed by Statistica 12 for Windows operating system. Mean, standard deviation, range, variability coefficient, skewness and kurtosis were used as descriptive parameters, as well as Pearson correlation coefficient, Spearman-Brown alpha, Cronbach`s alpha and Spearman-Brown (standardized) alpha. Results: Classically and digitally measured height in average results do not differ significantly, while for lengths of the left forearm and the left lower leg do indicate significant differences (lower values). The differences could be attributed to different reference points used in two measurement methods. Measures of internal consistency (reliability) for digitally measured variables: height of the body, length of left forearm and length of left lower leg demonstrate high reliability (Cronbach alpha, the standardized alpha 0.995 to 0.997) and the average inter-item correlation (0.973 to 0.985), indicates a high internal consistency between items related to digitally measured height. Reliability was slightly lower for digitally measured length of the left forearm and lower leg due to greater differentiation in average inter-item correlations coefficients. Conclusions: Digital measurements with Kinect are not appropriate for clinical trials demanding high precision. There is no statistical evidence that could differentiate distances of examinee from Kinect sensor in order to define optimal distance (as long as subject stands within Kinects range. Small errors occur due to clothing, possibly due to illumination, and sensor height and distance, which is in line with previous research.
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Short Papers
Paper Nr: 9
Title:

A Convolution Model for Heart Rate Prediction in Physical Exercise
Authors:

Melanie Ludwig, Harald G. Grohganz and Alexander Asteroth
Abstract: During exercise, heart rate has proven to be a good measure in planning workouts. It is not only simple to measure but also well understood and has been used for many years for workout planning. To use heart rate to control physical exercise, a model which predicts future heart rate dependent on a given strain can be utilized. In this paper, we present a mathematical model based on convolution for predicting the heart rate response to strain with four physiologically explainable parameters. This model is based on the general idea of the Fitness-Fatigue model for performance analysis, but is revised here for heart rate analysis. Comparisons show that the Convolution model can compete with other known heart rate models. Furthermore, this new model can be improved by reducing the number of parameters. The remaining parameter seems to be a promising indicator of the actual subject’s fitness.
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Paper Nr: 10
Title:

Performance Analysis of Basketball Referees by Machine Learning Techniques
Authors:

Sheng-Wei Wang and Wen-Wei Hsieh
Abstract: Basketball referees are important in a basketball game. In this paper, we analyze the performance of basketball referees in a game from history data and using the machine learning techniques. The data are collected from Taiwan Super Basketball League games. We first observed that the teamwork is a key factor to the performance of referee teams. Furthermore, the degree of teamwork are more important than the personal capabilities. Then, we derived some classifiers by machine learning algorithms to further analyze the data set. Among the three classifiers, a classifier named linear classifier using pocket algorithm, which is able to classify the data points with most correct rate, performs better than the other two classifiers. The classifier also proved the importance of teamwork is much larger than that of personal capability. In the future, the classifier can be used to predict the performance of a referee team in a basketball game.
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Paper Nr: 22
Title:

Numerical Simulation and Experimental Scheme for Monitoring Hoof Wall Structure and Health in Sport Horses
Authors:

K. Hanstorp, B. M. Mihiretie, M. Karlsteen, A. Rosén, M. Sundin, D. Cederkrantz, H. Otterberg, Å. Hinton and B. Berg
Abstract: This study provides a computational model developed to demonstrate the possibility of monitoring hoof structure and health in equestrian sport. This is achieved by employing finite element simulation of three-dimensional heat flow from a surface heat source into a hoof structure while simultaneously sensing the surface temperature. The time evolution of the recorded surface temperature, transient curve, is used to investigate hoof structure and predict its intactness by comparing these curves for three different models. We have observed differences between the transient curves obtained from a normal hoof structure, a hoof structure containing a foreign material and hoof capsule subjected to wall separation. An experimental method for probing hoof profile was briefly discussed. It uses temperature sensor/heat source. The method can determine the thermal conductivity of the hoof along the hoof structure from the recorded transient curve. Thus, it displays the hoof structure by utilizing the thermal conductivity variation between the hoof parts.
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Paper Nr: 24
Title:

Analysis of Curling Team Strategy and Tactics using Curling Informatics
Authors:

Hiromu Otani, Fumito Masui, Kohsuke Hirata, Hitosi Yanagi and Michal Ptaszynski
Abstract: The 2015-2016 season became a historic season for Japanese curling. Japan national curling team has won a silver medal for the first time at the 46th Women's World Championship 2016 in Canada. However, it is still necessary to work on strengthening the team performance in order to aim for the top. Such strengthening needs to include material factors such as the physical factor and the human factor, but also the strategic/tactical factor which is crucial in curling. Bradley (2009) points out the strategic/tactical factor as the most important at top level. As an example of a research aimed at supporting such strengthening of the strategic/tactical factor, Masui et al. (2016) proposed the concept of Curling Informatics. They built an environment for strategic/tactical support which makes use of ICT by allowing digitally collect and analyze game informations in real time. Specifically, as the first step of implementation they developed a digital scorebook $iCE$ as a method for digital collection of game information for further analysis. In this research we analyzed game information collected with $iCE$ to establish the effective analysis for tactical support and verify the knowledge which can be obtained empirically and what kind of new knowledge can be obtained from it. We report on the new knowledge we obtained regarding the relationship between shot accuracy and difference in game scores, and difference in correlation for each level in 93 games collected during the 2013-2014 season.
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Paper Nr: 27
Title:

Differential GNSS for Outdoor Sports - Testing of Applicability for Alpine Sports
Authors:

Johan Samuelsson, Magnus Karlsteen and Christian Finnsgård
Abstract: The purpose of this paper is to evaluate a differential GNSS (global navigation satellite system) tracking technology and whether it can be applied in alpine sports. Wearable technology is a technology undergoing extensive development. Wearable technology is an umbrella term for technology that can be worn, providing the user with different kinds of information. In sports, this is often related to performance of athletes. This paper is evaluating a tracking technology and whether it can be applied in an alpine environment, tracking both cross country skiers as well as down hill skiers. The technology applied in the product is a DGNSS, a differential Global Navigation Satellite System, a high accuracy positioning technology. The GNSS is using several satellite systems, providing coverage at all times. The differential part comes from the use of an accurately surveyed reference station, providing the rover with correction signals and thereby give a higher accuracy on tracking data. The technology shows promising results in accuracy in the measurement method used, but needs further evaluation using continuous measurements.
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Paper Nr: 46
Title:

Detection of Players on a Soccer Team based on Informed Filters using Only Color Features
Authors:

Takuro Oki and Ryusuke Miyamoto
Abstract: Recently, semantic analysis of sports videos has become an active research topic. In particular, player detection on the field is an important technique for various applications, such as calculations of distance covered by a player during a soccer game that are essential for semantic event detection and tactical analysis. Tracab is one of the most famous systems that can visualize the statistics of players’ performance during the game. However, the current detection and tracking systems used for Tracab are very large and expensive, therefore they are only found at large stadiums. This system is also required by many major teams in order to play a match. To solve this problem, we tackled this task by using a simple monocular camera and proposed an high accurate soccer player detection method with only color features in (Miyamoto and Oki, 2016). This method is based on a simple sliding window algorithm, however it does not use background subtraction and inter-frame difference. This is because they are not appropriate for moving cameras, though we require our system to operate properly for aerial photographs taken by drones. In (Miyamoto and Oki, 2016), we tried to found all humans on the field including coaches and referees. However, for team tactics and player activity analysis, it is more useful to detect only players that belong to a certain team. Therefore, in this paper, we improve (Miyamoto and Oki, 2016) method and try to enable accurate detection of soccer players based on their belonging teams.
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Paper Nr: 48
Title:

Makin Every Second Count - Implementation of the Smart Rings Jury Tool to Evaluate Hold Time during the Men’s Artistic Gymnastics European Championships 2016
Authors:

M. J. J. J. Aarts, L. A. J. Wolfs and A. H. M. Pluk
Abstract: Within competitive gymnastics, a still rings routine consists of swing, strength and hold elements. The difficulty and execution of these elements is evaluated by a panel of judges. Although the human eye can distinguish quite accurately between different elements and whether an element is correctly executed, internal research by the European Gymnastics Union (UEG) has shown that the timing of the strength and hold elements is less accurate. Consistent and precise timing of these elements is crucial, because a deduction of 0.3 point must be given when the Hold Time (HT) is less than 2.0 seconds. This deduction could make a big difference as can be seen in small gaps of the scores of the still rings final at the EC in 2014 and 2015: 0.200 point between first and fifth place and 0.333 point between second and last place respectively. A digital support tool, Smart Rings Jury Tool, was developed to support the evaluation of HT. The aim of this study was to implement and evaluate this tool during the Men’s Artistic Gymnastics (MAG) European Championships 2016
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Paper Nr: 23
Title:

A Fuzzy-based Software Tool Used to Predict 110m Hurdles Results During the Annual Training Cycle
Authors:

Krzysztof Przednowek, Krzysztof Wiktorowicz, Tomasz Krzeszowski and Janusz Iskra
Abstract: This paper describes a fuzzy-based software tool for predicting results in the 110m hurdles. The predictive models were built on using 40 annual training cycles completed by 18 athletes. These models include: ordinary least squares regression, ridge regression, LASSO regression, elastic net regression and nonlinear fuzzy correction of least squares regression. In order to compare them, and choose the best model, leave-one-out cross-validation was used. This showed that the fuzzy corrector proposed in this paper has the lowest prediction error. The developed software can support a coach in planning an athlete's annual training cycle. It allows the athlete's results to be predicted, and in this way, for the best training loads to be selected. The tool is a web-based interactive application that can be run from a computer or a mobile device. The whole system was implemented using the R programming language with additional packages.
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Area 2 - Health, Sports Performance and Support Technology

Full Papers
Paper Nr: 21
Title:

3D Interactive Environment Applied to Fencing Training
Authors:

Carla Patricia Guimaraes, Vitor Balbio, Gloria Lopez Cid, Maria Isabel Orselli, Ana Paula Xavier, Augusto Siqueira neto and Sonia Cavalcanti Corrêa
Abstract: The purpose of this study was to present a 3D interactive environment - a Digital Platform to help in fencing training. The first fencing motion described and analysed at the 3D platform was lunge in epee fencing. The platform was able to show kinematic variables of upper and lower limbs and the center of mass that characterized a good performance in epee fencing. The platform also incorporates a digital database of eye track motions of the fencers. An OptiTrack motion capture system was used to capture the lunge motion of five skilled amateur fencing athletes in the presence or not of a static opponent and an Eye Track System Tobbi II was used to track the eye movements of the fencers when performing a lunge attack with a target. The 3D platform was developed using Unity3D and can present some interesting results to improve available information to coaches. That highlights the importance of visualization biomechanical results based on coach criteria in a more understandable way to help athletic training.
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Paper Nr: 29
Title:

A Study on the Improvement of Public Bicycle Services - Focused on South Korean Cases
Authors:

Yong-Wook Kim and Tea-Seong Lim
Abstract: This study analyzes public bicycle service trends in Korea. First, several cases of small Korean cities with the highest number of public bicycles were researched. The research results showed that bicycles were used 2,152 times a day with an average of 69 min spent on using the vehicle. Second, the public bicycle service in Daejeon, a metropolitan in Korea, was analyzed. Factors considered in the utilization rate of bicycles were neighboring schools, subway stations, and parks. When calculating the expected utilization rate, ten stations with low usage were assumed to be relocated. In this case, it was confirmed that the utilization rate increased by 34.00%.
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Paper Nr: 40
Title:

Possibility of Modern Humidity Sensor Application in the Studies of Moisture Transport through the Sports and Outdoor Garments
Authors:

Andrey Koptyug, Mats Ainegren, Mikael Bäckström, Erika Schieber and Jonas Persson
Abstract: Sensor nodes containing pairs of temperature and humidity sensors were assessed as a mean of garment performance and comfort studies. Modern sensors are small, low weight and produce minimal disturbance when placed under the garments and in the footwear. Four sensor nodes were used to provide dynamic information about heat and humidity transfer properties of garments during the tests in realistic conditions. Pilot studies were carried out for the few models of cross country skiing garments and waders. Main studies were carried out in the wind tunnel at Mid Sweden University having pivoted treadmill, temperature control and rain capacity. Additional experiments with the waders were carried out in a large water tank. Studies of the temperature and humidity dynamics under the garments containing microporous membranes illustrate the importance of recognizing main features of such materials. In particular, such membranes can only transport moisture from the side where humidity is higher. It means that garments and footwear containing such membranes will potentially behave differently when ambient air humidity changes. In particular, modern garments with incorporated microporous membranes being superior at low ambient air humidity can be dramatically less effective for moisture transfer from the body in the rain.
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Paper Nr: 47
Title:

Stress Level Monitoring in Car Racing - Examples of Measurements during Races
Authors:

Joachim Taelman, Pieter Joosen, Jean-Marie Aerts, Vasileios Exadaktylos and Daniel Berckmans
Abstract: Car racing at a high level is a physically and mentally intensive sport. Despite the fact that a large number of variables are measured on the car during racing, nothing is measured on the driver. It is well known that to achieve peak performance in competitive sports it is important that the athlete is at their peak both physically and mentally. The objective of this work is to monitor the mental state of the driver in real-time and provide this information to the pit crew. A number of interesting cases are presented that show the potential of real-time stress monitoring in race car driving as a means for driver performance optimisation and as a means to reduce accidents.
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Paper Nr: 55
Title:

Validity and Reliability of the 3D Motion Analyzer in Comparison with the Vicon Device for Biomechanical Pedalling Analysis
Authors:

Anthony Bouillod, Antony Costes, Georges Soto-Romero, Emmanuel Brunet and Frédéric Grappe
Abstract: The present work aimed to assess the validity and reliability of the 3D motion analyzer (Shimano Dynamics Lab, Sittard, Netherland) during laboratory cycling tests in comparison with the Vicon device (Vicon Motion Systems Ltd. Oxford, UK). Three cyclists were required to complete one laboratory cycling test at three different pedalling cadence and at a constant power output. Kinematic measurements were collected simultaneously from 3D motion analyzer and Vicon devices and performed five times for each pedalling cadence. The two systems showed a high reliability with excellent intraclass correlation coefficients for most kinematic variables. Moreover, this system was considered as valid by considering the error due to the initial markers placement. Experts and scientists should use the Vicon system for the purpose of research whereas the 3D motion analyzer could be used for bike fitting.
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Paper Nr: 60
Title:

Preliminary Study: A New Method to Assess the Effective Frontal Area of Cyclists
Authors:

Anthony Bouillod, Luca Oggiano, Georges Soto-Romero, Emmanuel Brunet and Frederic Grappe
Abstract: The present work aimed to assess the effective frontal area (ACd, m2) of a cyclist using both 3D scanning and Computational Fluid Dynamics (CFD) simulation and compare the results with wind tunnel and field measurements. One elite cyclist was recruited to complete a 3D scanning, a wind tunnel test and a field test. The 3D scanning was analyzed using CFD simulation to determine the ACd of the cyclist. The CFD ACd was compared to those measured in both wind tunnel and field tests. The 3D scanning method provides useful data for cycling science and TT position or equipment optimization, by using iterative approach. Indeed, the ACd obtained after CFD simulation was in accordance with those obtained in both wind tunnel and field testing sessions. Resolution, scanning time and post processing are compatible with an extensive use in real conditions and with a larger number of cyclists.
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Short Papers
Paper Nr: 20
Title:

Training Simulation with Nothing but Training Data - Simulating Performance based on Training Data Without the Help of Performance Diagnostics in a Laboratory
Authors:

Melanie Ludwig, David Schaefer and Alexander Asteroth
Abstract: Analyzing training performance in sport is usually based on standardized test protocols and needs laboratory equipment, e.g., for measuring blood lactate concentration or other physiological body parameters. Avoiding special equipment and standardized test protocols, we show that it is possible to reach a quality of performance simulation comparable to the results of laboratory studies using training models with nothing but training data. For this purpose, we introduce a fitting concept for a performance model that takes the peculiarities of using training data for the task of performance diagnostics into account. With a specific way of data preprocessing, accuracy of laboratory studies can be achieved for about 50% of the tested subjects, while lower correlation of the other 50% can be explained.
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Paper Nr: 26
Title:

Effects of Dimple on Soccer Ball Aerodynamics
Authors:

Sungchan Hong and Takeshi Asai
Abstract: Typically, soccer balls are constructed with 32 pentagonal and hexagonal panels. More recently Teamgeist and Jabulani balls have 14 and 8 panels, respectively, with dramatically different panel shapes and designs from conventional balls. The latest model called Beau Jeu, made with 6 panels, has been adopted by many soccer leagues. However, there are few studies on the aerodynamic characteristics of these balls. This study examined the trajectory and aerodynamic characteristics of soccer balls constructed with different numbers and shapes of panels. Results of wind tunnel tests indicated that the aerodynamic forces varied significantly according to the surface forms. The results showed that the ball trajectory changes according to surface form, suggesting that surface form has significant effects on the flight of the balls.
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Paper Nr: 32
Title:

The Effects of Thermal-isolation Pads Placed over Working Muscles on Endurance Performance
Authors:

S. Wenger, R. Csapo and W. Nachbauer
Abstract: The aim of this study was to test the effects of thermal insulation of working muscles on parameters reflecting physical stress provoked by a moderately intense endurance task in a cold environment.
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Paper Nr: 33
Title:

Isokinetic Knee Muscle Strength Profile in Brazilian Male Soccer, Futsal and Beach Soccer Players
Authors:

Claudio de Lira, Naryana Mascarin, Valentine Vargas, Rodrigo Vancini and Marilia Andrade
Abstract: The main objective of this study was to investigate isokinetic knee muscle strength, hamstring to quadriceps (H/Q) strength ratio, and bilateral strength deficit in professional futsal, soccer and beach soccer players. We hypothesized that athletes of different soccer modalities have a specific isokinetic profile due to physiological, playing surface and biomechanical demands and specificities.
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Paper Nr: 41
Title:

Detection of Single Ball Contacts using a Radio-based Tracking System - A Basis for Technical Performance Analysis
Authors:

Nicolas Witt, Matthias Völker and Björn M. Eskofier
Abstract: The usage of tracking technology in sports became standard in most major team sports like soccer, basketball or American football. Official tracking in soccer is done by video tracking and is currently limited to physical assessments of the players. New high rate tracking technologies for players and balls could also enable a detailed technical assessment of athletes. This work investigates the detection of single ball contacts, distinguishing left and right foot, using a radio based real-time tracking system. Ball tracking is done at 2000 Hz and player tracking at 200 Hz. Miniaturized transmitters were attached to the shins, enabling the distinction between left and right contacts with the ball. Data acquisition was done in an indoor environment. Six small sided games (749 contacts) and 25 repetitions of training exercises (195 contacts) were recorded. The ground truth of 941 single ball contacts was assessed by video annotation. Detection in the training scenario shows a precision of 97-100 % and a recall of 87-100 %. For the game scenario, precision is 89 % and recall reaches 93 %. Detection errors mainly affect non crucial contacts during longer dribblings, which are not the main interest of many analyses. The high precision and recall rates indicate a solid base for higher level technical assessments in automatic match (statistics) and training analysis (skill evaluation).
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Paper Nr: 61
Title:

Comparison of Pedobarographic Profile in Young Males with Left and Right Scoliotic Posture
Authors:

Igor Gruić, Karlo Cebović and Vladimir Medved
Abstract: Background: Scoliosis alters both posture and gait. Pedobarography is a biomechanical method for assessing gait that has been rarely used in scoliosis-specific gait research. Objective: To determine differences between left and right scoliotic posture in plantar pressure and force gait profile among young males. Methods: Twenty-one young, trained males assigned to one of two groups: left scoliotic posture (LSP; N=12) and right scoliotic posture (RSP; N=9) group. Subjects were assigned to a group based on forward-bending test and controlled for age, height, weight, body mass index (BMI), right and left leg length. All subjects were blinded for group they were assigned and study outcomes. Examiners were blinded for study outcomes. Subjects walked at self-selected speed along the 9,5-meter-long walkway for 2 minutes. Plantar pressures and forces were measured using pedobarographic device Zebris medical FDM 1.5. Measured outcomes during gait included: Maximum force right foot (N), Maximum force left foot (N), Maximum force at first contact right foot (N), Maximum force at first contact left foot (N), Maximum force at take-off right foot (N), Maximum force at take-off left foot (N), Maximum forefoot force right foot (N), Maximum forefoot force left foot (N), Maximum midfoot force right foot (N), Maximum midfoot force left foot (N), Maximum heel force right foot (N), Maximum heel force left foot (N), Maximum forefoot pressure right foot (N/cm2), Maximum forefoot pressure left foot (N/cm2), Maximum midfoot pressure right foot (N/cm2), Maximum midfoot pressure left foot (N/cm2), Maximum heel pressure right foot (N/cm2), Maximum heel pressure left foot (N/cm2). Results: There were no significant differences in any observed foot pressure or force gait parameter between left and right scoliotic posture group (p<0,05). Conclusion: Plantar pressure and force gait parameters seems to have no diagnostic value in determining scoliosis-specific gait. Focus should be shifted to other pedobarographic gait parameters (e.g. center of pressure, time-force parameters, etc.). Future research should investigate relationships between biomechanical movement compensation and neuromuscular, musculo-skeletal and genetic factors that may initiate scoliosis.
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Paper Nr: 15
Title:

Evaluation of a Roller Skating Performance Test
Authors:

Ivan Radman, Domagoj Primuzak, Viktoria Padovan, Vjekoslav Cigrovski, Đurđica Ivankovic and Lana Ruzic
Abstract: The study aimed to evaluate recently developed roller skating performance test. Groups of recreational and competitive skaters first self-assessed their roller skating skill and then repeated the test in four separate occasions. No significant changes in performance time were evident between any of four trials. The test had low mean within-individual variation and high inter-sessions correlation. In addition, it discriminated skating performances of competitive and recreational skaters. Besides, moderate correlations were recorded between skater’s self-rating and achieved test results. Finally, results suggest that evaluated test is reliable, valid and sufficiently sensitive to be applied in amateur roller skating practice.
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Paper Nr: 30
Title:

Relationship of Step Width with Sprinting Performance and Ground Reaction Forces
Authors:

Ryu Nagahara, Mirai Mizutani and Akifumi Matsuo
Abstract: The purpose of this study was to clarify the relationship of step width with sprinting performance and ground reaction forces in order to understand the sprinting mechanism and its relation to better sprinting performance.
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Paper Nr: 43
Title:

Technologies of Effective Training Control in Amateur Triathlon - Non-Invasive Hemodynamic Measurements and Exercise Testing for Accurate Training Prescription
Authors:

Anna Zakharova and Kamiliia Mekhdieva
Abstract: Although issues of training in professional triathlon are well highlighted and studied, the approach to supply, including medical-pedagogical aspects, still remains under debates in amateur triathlon. The intensity and volume of exercise loads in amateur triathlon tend to those in professional sports, whereas there is no consensus on efficient training strategy for active individuals engaged in amateur endurance sports. The objective of the study was to define the role of cardiovascular testing in training program design in amateur triathlon. Twenty-four healthy active male amateur triathletes aged 26-43 years participated in the study. Four trials of testing (hemodynamics and gas-exchange monitoring) were conducted to justify the amendments to training schedule. Based on significant differences of initial hemodynamic parameters (SV, SI, EDV, EDI) subjects were divided into 2 groups. Determining of the weak aspects of their functional state enabled to develop an efficient training schedule at the ongoing experiment stages. The obtained results of the final testing showed significant increase in VO2max, maximal power (Pmax) in cycling stress-test and LV volume characteristics in amateur triathletes.
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Area 3 - Signal Processing and Motor Behavior

Full Papers
Paper Nr: 37
Title:

Objective Classification of Dynamic Balance Using a Single Wearable Sensor
Authors:

William Johnston, Martin O'Reilly, Kara Dolan, Niamh Reid, Garrett F. Coughlan and Brian Caulfield
Abstract: The Y Balance Test (YBT) is one of the most commonly used dynamic balance assessments in clinical and research settings. This study sought to investigate the ability of a single lumbar inertial measurement unit (IMU) to discriminate between the three YBT reach directions, and between pre and post-fatigue balance performance during the YBT. Fifteen subjects (age: 23±4, weight: 67.5±8, height: 175±8, BMI: 22±2) were fitted with a lumbar IMU. Three YBTs were performed on the dominant leg at 0, 10 and 20 minutes. A modified Wingate fatiguing intervention was conducted to introduce a balance deficit. This was followed immediately by three post-fatigue YBTs. Features were extracted from the IMU, and used to train and evaluate the random-forest classifiers. Reach direction classification achieved an accuracy of 97.80%, sensitivity of 97.86±0.89% and specificity of 98.90±0.56%. “Normal” and “abnormal” balance performance, as influenced by fatigue, was classified with an accuracy of 61.90%-71.43%, sensitivity of 61.90%-69.04% and specificity of 61.90%-78.57% depending on which reach direction was chosen. These results demonstrate that a single lumbar IMU is capable of accurately distinguishing between the different YBT reach directions and can classify between pre and post-fatigue balance with moderate levels of accuracy.
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Short Papers
Paper Nr: 49
Title:

Hitting Kinematics for Precise Ball-Bat Contact in Collegiate Baseball Hitters
Authors:

Jun Misaki, Takatoshi Higuchi, Ryo Tsuchikane, Hiromichi Saeki and Tadao Isaka
Abstract: In baseball, higher bat velocity and the bat control are required for the successful hitting. Although kinematical factors related bat velocity have been studied, the knowledge about hitting kinematics related ball-bat contact precision is limited. The aim of this study was to examine the hitting kinematics for precise ball-bat contact in collegiate baseball hitters. Ten collegiate baseball field players completed 20 swings at a ball on the baseball tee, and their joint angles were calculated. The results indicate that hitters with lower precision in ball-bat contact might have excessive variability in joint angles in trail arm.
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Paper Nr: 31
Title:

Motor and Neural Adaptation during an Eight-Week Writing Training with the Non-Preferred Hand
Authors:

Manuel Bange, Gaëtan André and Diana Henz
Abstract: The ability to adapt to a dynamic environment plays a crucial role in the success of human development. By applying an exploratory longitudinal single case study design to the task of learning to write with the non-preferred hand, we hoped to gather new insights about individual motor and neural adaptation. Previous studies showed that graphomotor skills are governed by nonlinear dynamic coupling of two (nearly) orthogonal oscillators, measured as relative phase (RP). We investigated the development of RP, velocity, and the number of velocity inversions (NIV) of the letter “e” during eight weeks of training. We found individual differences in the time courses of velocity and NIV, suggesting that subjects use different strategies (e.g. different feedback), evaluate constraints differently, and learn with a different pace. All participants exhibited decreasing standard deviation of RP, pointing towards the formation of increasingly stable attractors. This supports the idea that writing can be modelled by updating relative phase, amplitude and frequency on a piecewise manner. Spectral EEG mapping showed increased gamma activity on the whole cortex which indicates the engagement of a wide-spread network during graphomotor learning. Decreased frontal theta activity after the intervention supports the idea that subjects need less attention with higher task familiarity.
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Paper Nr: 45
Title:

The Foot Feature Measurement System and Its Application to Postural Stability of Healthy Subjects
Authors:

Kyung-Ryoul Mun, Sungkuk Chun, Hyungan Oh, Yunjung Kang, Junggi Hong and Jinwook Kim
Abstract: In this study we aimed to develop a foot feature measurement system (FFMS) being able to simultaneously extract foot feature parameters in both static and dynamic condition. In addition, we investigated how these foot features are associated to the postural stability through human experiments as this is one of the most important requirements for natural and aesthetic gait pattern. From all thirteen subjects participated in this study, this foot arch mechanism were clearly observed. It indicates that observation of LLA and area of MLA curves is important to investigate postural stability in accordance with the different type of foot arches. For the conclusion, foot anatomical characteristics such as height and the area of each arch curves can be observed in both static and dynamic condition using the FFMS. In addition, it can be concluded that the FFMS can provide more precise and various foot information by considering the LLA during both static and dynamic condition.
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Area 4 - Sports Medicine and Support Technology

Short Papers
Paper Nr: 1
Title:

Analysis of a Mobile System to Register the Kinematic Parameters in Ankle, Knee, and Hip based in Inertial Sensors
Authors:

Víctor H. Flores-Morales, Byron G. Contreras-Bermeo, Freddy L. Bueno-Palomeque and Luis J. Serpa-Andrade
Abstract: Understanding the lower-extremity kinematic during daily and sport activities provides important information in order to detect abnormalities in human gait or analyse the execution of different sport techniques. Following this approach, this paper presents a kinematic data collection system of human gait in the lower extremities using six inertial sensors MPU 6050 and a microcontroller ATMEGA328P-PU. Six tests were performed and the angular variation was recorded during the execution. The curves obtained during the tests showed a maximum error of ± 4, ± 1, and -4 degrees at the Yaw, Pitch, and Roll angles respectively. This study proposes a mobile and inexpensive system for detecting the angular variation in reduced speed movements, ideal for goniometric measurement or analyse the techniques in certain sports.
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