F. Menhorn, Chris Hummel, Andreas Huber, Karlheinz Waibel, H. Bungartz, Peter Spitzenpfeil
We introduce a novel approach for computing gate-to-gate time automatically from audio recordings. In slalom skiing, gate-to-gate timing is a valuable metric for athletes and trainers, capturing the time elapsed between slalom gates. The availability of these measurements immediately after each run allows for prompt feedback. This study specifically concentrates on gate-to-gate timing in alpine slalom skating, serving as a foundational step towards its future application in slalom skiing. While existing methods for measuring gate-to-gate time vary in their feasibility, accuracy, and compliance with regulations, we propose a solution utilizing a convolutional neural network (CNN) to predict gate locations using the audio signals generated upon gate contact. By leveraging these predictions, we achieve fully automated computation of gate-to-gate timings. We conduct a comparative analysis between the CNN’s predictions and data obtained from an inertial measurement unit. Our findings reveal a strong predictive correlation between the two methods, with an R-squared value of 0.94 and a root mean squared error of 0.036. The majority of predictions demonstrate high accuracy, falling within a range of thousandths of a second. However, a few outliers negatively impact the overall performance. Notably, we observe no deterioration in predictive quality based on the distance between the camera and the gate. Finally, we delve into the challenges and limitations associated with our approach and provide a comprehensive discussion. To conclude, we outline potential avenues for future research and extensions of our methodology to the realm of slalom skiing.
{"title":"Automatic gate-to-gate time recognition from audio recordings in slalom skiing using neural networks","authors":"F. Menhorn, Chris Hummel, Andreas Huber, Karlheinz Waibel, H. Bungartz, Peter Spitzenpfeil","doi":"10.36950/2024.3ciss003","DOIUrl":"https://doi.org/10.36950/2024.3ciss003","url":null,"abstract":"We introduce a novel approach for computing gate-to-gate time automatically from audio recordings. In slalom skiing, gate-to-gate timing is a valuable metric for athletes and trainers, capturing the time elapsed between slalom gates. The availability of these measurements immediately after each run allows for prompt feedback. This study specifically concentrates on gate-to-gate timing in alpine slalom skating, serving as a foundational step towards its future application in slalom skiing.\u0000While existing methods for measuring gate-to-gate time vary in their feasibility, accuracy, and compliance with regulations, we propose a solution utilizing a convolutional neural network (CNN) to predict gate locations using the audio signals generated upon gate contact. By leveraging these predictions, we achieve fully automated computation of gate-to-gate timings.\u0000We conduct a comparative analysis between the CNN’s predictions and data obtained from an inertial measurement unit. Our findings reveal a strong predictive correlation between the two methods, with an R-squared value of 0.94 and a root mean squared error of 0.036. The majority of predictions demonstrate high accuracy, falling within a range of thousandths of a second. However, a few outliers negatively impact the overall performance. Notably, we observe no deterioration in predictive quality based on the distance between the camera and the gate.\u0000Finally, we delve into the challenges and limitations associated with our approach and provide a comprehensive discussion. To conclude, we outline potential avenues for future research and extensions of our methodology to the realm of slalom skiing.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141018547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flow field measurements around cross-country skiers (xc skiers) are lacking in the literature to date. The aim was therefore to investigate the possibility of using particle tracking velocimetry for visualization and measurement of the flow field around xc skiers roller skiing on a treadmill in a wind tunnel. The airflow was seeded with neutrally buoyant helium-filled soap bubbles as tracer particles, following the flow without affecting it. As illumination, two different approaches were tested: first, a laser in the cameras’ line of sight (sagittal plane), then an LED unit directed vertically in a narrow slice, clearly limiting the depth of the measurement volume in the cameras’ line of sight. The flow field was studied at various speeds (3-7 m/s) around a single skier as well as around two skiers in line with the streaming airflow. It was found that the experimental approach has the potential to provide detailed insights, both qualitatively and quantitatively, into the flow field dynamics. The main challenges regarding setup, illumination, seeding, and cameras were identified, and possible improvements to streamline the experimental methodology were discussed.
迄今为止，还没有文献对越野滑雪者（xc 滑雪者）周围的流场进行过测量。因此，我们的目的是研究使用粒子跟踪测速仪对在风洞中跑步机上滚轴滑雪的越野滑雪者周围流场进行可视化测量的可能性。气流中加入了中性浮力的氦气肥皂泡作为示踪粒子，在不影响气流的情况下跟踪气流。在照明方面，测试了两种不同的方法：首先是在相机视线内（矢状面）使用激光，然后是在狭窄切片内垂直照射 LED 装置，这明显限制了相机视线内测量体积的深度。我们以不同的速度（3-7 米/秒）研究了单个滑雪者周围的流场，以及两个滑雪者周围与流动气流一致的流场。研究发现，这种实验方法有可能从定性和定量两个方面详细了解流场动态。研究确定了在设置、照明、播种和相机方面的主要挑战，并讨论了简化实验方法的可能改进措施。
{"title":"Towards flow field measurements around dynamic cross-country skiers","authors":"Sofia Larsson, Henrik Lycksam, M. Ainegren","doi":"10.36950/2024.3ciss006","DOIUrl":"https://doi.org/10.36950/2024.3ciss006","url":null,"abstract":"Flow field measurements around cross-country skiers (xc skiers) are lacking in the literature to date. The aim was therefore to investigate the possibility of using particle tracking velocimetry for visualization and measurement of the flow field around xc skiers roller skiing on a treadmill in a wind tunnel. The airflow was seeded with neutrally buoyant helium-filled soap bubbles as tracer particles, following the flow without affecting it. As illumination, two different approaches were tested: first, a laser in the cameras’ line of sight (sagittal plane), then an LED unit directed vertically in a narrow slice, clearly limiting the depth of the measurement volume in the cameras’ line of sight. The flow field was studied at various speeds (3-7 m/s) around a single skier as well as around two skiers in line with the streaming airflow. It was found that the experimental approach has the potential to provide detailed insights, both qualitatively and quantitatively, into the flow field dynamics. The main challenges regarding setup, illumination, seeding, and cameras were identified, and possible improvements to streamline the experimental methodology were discussed.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"21 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141023157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martine Aalberg, T. Roaas, M. A. Aune, Tore Kristian Aune
The overall purpose of the present study was to investigate similarities and differences in pathways to expertise for freeskiers and cross-country skiers. Specifically, 1) Entrance to the main sport, 2) Amount of training hours and organization of training, and 3) Variability in activities and content in training. Sampling athletes had to be on the highest level in their sport by competing in, e.g., the World Cup, World Championship, Olympic games, freeride World Tour. In total, 18 world-class skiers participated in the study. Eight freeskiers (age range 19-37) and ten cross-country skiers (age range 22-32 years). They answered a digital questionnaire designed to collect retrospective data describing their pathways to expertise. The first section elicits biographical information, age for entering sport and practice. The second section focused on sport-specific training, accumulated hours of training, and the distribution of organized versus self-organized training. The third section recalled the variability of activities they participated in and how they perceived the relevance of the content of different types of training for their sport-specific development. The results showed similarities in athletes’ entrance to the main sport, specialization age and total amount of training. At the same time, differences were observed in their training history regarding the organization of training. In contrast to cross-country skiers, freeskiers seem to be more self-organized and more involved in additional activities besides their main sport. Interestingly, the two groups of world-class athletes representing sports with distinctive demands share several common variables in their paths to expertise, amplified by perceived specificity. Practitioners and academics should substantiate patience in expertise development, driven by a multi-disciplinary understanding of distinct and individual characteristics or conditions that may be beneficial in fulfilling varied future demands. Hence, research should explore the rationale behind and potential learning effects between sports and training content.
{"title":"Development of world class ski performance: Similarities and differences in pathways to expertise for freeskiers and cross-country skiers","authors":"Martine Aalberg, T. Roaas, M. A. Aune, Tore Kristian Aune","doi":"10.36950/2024.3ciss007","DOIUrl":"https://doi.org/10.36950/2024.3ciss007","url":null,"abstract":"The overall purpose of the present study was to investigate similarities and differences in pathways to expertise for freeskiers and cross-country skiers. Specifically, 1) Entrance to the main sport, 2) Amount of training hours and organization of training, and 3) Variability in activities and content in training. Sampling athletes had to be on the highest level in their sport by competing in, e.g., the World Cup, World Championship, Olympic games, freeride World Tour. In total, 18 world-class skiers participated in the study. Eight freeskiers (age range 19-37) and ten cross-country skiers (age range 22-32 years). They answered a digital questionnaire designed to collect retrospective data describing their pathways to expertise. The first section elicits biographical information, age for entering sport and practice. The second section focused on sport-specific training, accumulated hours of training, and the distribution of organized versus self-organized training. The third section recalled the variability of activities they participated in and how they perceived the relevance of the content of different types of training for their sport-specific development. The results showed similarities in athletes’ entrance to the main sport, specialization age and total amount of training. At the same time, differences were observed in their training history regarding the organization of training. In contrast to cross-country skiers, freeskiers seem to be more self-organized and more involved in additional activities besides their main sport. Interestingly, the two groups of world-class athletes representing sports with distinctive demands share several common variables in their paths to expertise, amplified by perceived specificity. Practitioners and academics should substantiate patience in expertise development, driven by a multi-disciplinary understanding of distinct and individual characteristics or conditions that may be beneficial in fulfilling varied future demands. Hence, research should explore the rationale behind and potential learning effects between sports and training content.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"4 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141020997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martin Gallimore, Edouard Koehn, Mario Schlegel, Leon Stillhard, Andreas Vetsch, Björn Peter Bruhin, Martin J. Bünner
Using tracking data we can identify the optimal racing line for top male athletes on the famous S-curved segment (Brueggli-S) of the downhill FIS world cup track “Lauberhorn” in Switzerland. For this, we have measured and analysed training runs, measured on a single day, of 10 world class athletes. Based on curvatures derived from the tracking data, a large variation in racing lines adopted by the athletes was observed. Each of the detected racing lines share a similar pattern: The maximum curvature in the first curve is strongly correlated with the minimum curvature of the second curve. We have found that, for the athletes under investigation, the overall best racing line is characterized by a defined ratio of the maximum curvature of the first to the second curve. We claim that the observed correlation, as well as the optimal ratio of curvatures, is universal for a class of athletes with nearly identical performance levels. If and how this ratio varies for different classes of athletes (i.e. U10, U12 or U16 athletes) is an as yet unanswered question and remains open to further investigation.
{"title":"Identification of the optimal racing line for top male athletes on a segment of a World Cup downhill alpine ski slope using tracking data","authors":"Martin Gallimore, Edouard Koehn, Mario Schlegel, Leon Stillhard, Andreas Vetsch, Björn Peter Bruhin, Martin J. Bünner","doi":"10.36950/2024.3ciss002","DOIUrl":"https://doi.org/10.36950/2024.3ciss002","url":null,"abstract":"Using tracking data we can identify the optimal racing line for top male athletes on the famous S-curved segment (Brueggli-S) of the downhill FIS world cup track “Lauberhorn” in Switzerland. For this, we have measured and analysed training runs, measured on a single day, of 10 world class athletes. Based on curvatures derived from the tracking data, a large variation in racing lines adopted by the athletes was observed. Each of the detected racing lines share a similar pattern: The maximum curvature in the first curve is strongly correlated with the minimum curvature of the second curve. We have found that, for the athletes under investigation, the overall best racing line is characterized by a defined ratio of the maximum curvature of the first to the second curve. We claim that the observed correlation, as well as the optimal ratio of curvatures, is universal for a class of athletes with nearly identical performance levels. If and how this ratio varies for different classes of athletes (i.e. U10, U12 or U16 athletes) is an as yet unanswered question and remains open to further investigation.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"97 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141019098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Stöggl, Hans-Peter Wiesinger, Hermann Schwameder
Winter sports play a crucial role across individuals of all age groups, athletes or recreational enthusiasts with considerable health, economic and touristic importance. Besides these benefits challenges arise as equipment safety, athlete preparation to perform on highest level and prevent from injury, rehabilitation, sustainability, equipment etc. In this context, the International Congress on Science and Skiing (ICSS) has been a regular pivotal gathering for over 20 years. ICSS was hosted first time in 1996 in St. Christoph am Arlberg and celebrated in 2023 the 9th conference in Saalbach/Hinterglemm. The ICSS gathers winter sports experts around the world with up to 250 participants from more than 15 nations. Selected contributions were critically reviewed to be published Current Issues of Sport Science. The special issue demonstrates the broad spectrum of contributions in all fields and disciplines in winter sports.
{"title":"Proceedings of the Ninth International Congress on Science and Skiing (ICSS) – Saalbach/Hinterglemm March 2023","authors":"T. Stöggl, Hans-Peter Wiesinger, Hermann Schwameder","doi":"10.36950/2024.3ciss001","DOIUrl":"https://doi.org/10.36950/2024.3ciss001","url":null,"abstract":"Winter sports play a crucial role across individuals of all age groups, athletes or recreational enthusiasts with considerable health, economic and touristic importance. Besides these benefits challenges arise as equipment safety, athlete preparation to perform on highest level and prevent from injury, rehabilitation, sustainability, equipment etc. In this context, the International Congress on Science and Skiing (ICSS) has been a regular pivotal gathering for over 20 years. ICSS was hosted first time in 1996 in St. Christoph am Arlberg and celebrated in 2023 the 9th conference in Saalbach/Hinterglemm. The ICSS gathers winter sports experts around the world with up to 250 participants from more than 15 nations. Selected contributions were critically reviewed to be published Current Issues of Sport Science. The special issue demonstrates the broad spectrum of contributions in all fields and disciplines in winter sports.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"67 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141018048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Claudio R. Nigg, T. Stöggl, Hermann Schwameder, Hans-Peter Wiesinger, Daniel Turczyn, David Graham, Michael Lasshofer, John Seifert
Introduction The ski binding plays an important role in ski mountaineering. When traveling uphill, the binding has an adjustable heel height known as the riser. Previous laboratory research reported joint kinematics and kinetics are influenced by riser height, however little is known about changes to muscle activity associated with differing joint motion. The purpose of this work was to assess riser height influence on kinematics and muscle activity at different slopes during on-snow skiing. Methods Three female and nine male recreational ski mountaineers (19-26 y) were tested on 5o and 16o gradients using no riser (0 cm) and riser (5.3 cm) at a submaximal 80% HRmax. Each subject used Backland 85 UL skis and Backland Bindings (Atomic Skis, Altenmarkt, Austria). Subjects skied for 6 min at each binding setting with the last 10 gait-cycles evaluating lower limb joint motion gathered from 2D-sagittal plane motion capture. Electromyography (EMG) collected unilaterally on the rectus femoris, biceps femoris, medial gastrocnemius and triceps brachii also. Results 5o slope: hip range of motion (ROM) decreased (p = .003), ankle ROM decreased (p = .005), stride length decreased (p = .004), rating of perceived exertion (RPE) increased (p = .02) for riser compared to no riser. At 16o slope: hip ROM decreased (p = .001), and RPE decreased (p = .004) for riser compared to no riser. HR, glide distance, velocity, EMG, and net mechanical efficiency were not different between riser heights on either slope. Discussion/Conclusion Lower body joint kinematics, step length and RPE varied significantly with riser height. Kinematic differences did not impact velocity or muscle activity when controlling pace. These results agree with previous findings showing minimal differences in EMG and HR while lower body kinematics and RPE changed with riser height.
{"title":"Heel riser height influence on kinematics and muscle activity of ski mountaineering – A field based study","authors":"Claudio R. Nigg, T. Stöggl, Hermann Schwameder, Hans-Peter Wiesinger, Daniel Turczyn, David Graham, Michael Lasshofer, John Seifert","doi":"10.36950/2024.3ciss005","DOIUrl":"https://doi.org/10.36950/2024.3ciss005","url":null,"abstract":"Introduction\u0000The ski binding plays an important role in ski mountaineering. When traveling uphill, the binding has an adjustable heel height known as the riser. Previous laboratory research reported joint kinematics and kinetics are influenced by riser height, however little is known about changes to muscle activity associated with differing joint motion. The purpose of this work was to assess riser height influence on kinematics and muscle activity at different slopes during on-snow skiing.\u0000Methods\u0000Three female and nine male recreational ski mountaineers (19-26 y) were tested on 5o and 16o gradients using no riser (0 cm) and riser (5.3 cm) at a submaximal 80% HRmax. Each subject used Backland 85 UL skis and Backland Bindings (Atomic Skis, Altenmarkt, Austria). Subjects skied for 6 min at each binding setting with the last 10 gait-cycles evaluating lower limb joint motion gathered from 2D-sagittal plane motion capture. Electromyography (EMG) collected unilaterally on the rectus femoris, biceps femoris, medial gastrocnemius and triceps brachii also.\u0000Results\u00005o slope: hip range of motion (ROM) decreased (p = .003), ankle ROM decreased (p = .005), stride length decreased (p = .004), rating of perceived exertion (RPE) increased (p = .02) for riser compared to no riser. At 16o slope: hip ROM decreased (p = .001), and RPE decreased (p = .004) for riser compared to no riser. HR, glide distance, velocity, EMG, and net mechanical efficiency were not different between riser heights on either slope.\u0000Discussion/Conclusion\u0000Lower body joint kinematics, step length and RPE varied significantly with riser height. Kinematic differences did not impact velocity or muscle activity when controlling pace. These results agree with previous findings showing minimal differences in EMG and HR while lower body kinematics and RPE changed with riser height.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"17 52","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141020214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ski-snow interaction is the essential component of alpine skiing. To understand how a skier manipulates his ski to turn, we need to develop methods to measure the orientation of the ski throughout a complete run. Recent studies tried to use IMUs to estimate edge angle (EA) during skiing. We introduce and validate a method on how to calibrate and employ IMUs to precisely and accurately measure roll angles (RA) as a matter of changing orientation of the ski around its longitudinal axis in 3D space during skiing. Static orientation measurements on an inclined plane perfectly correlate (r2 = 1) with 3D motion capturing: RMSE = 0.18° and 0.24° respectively. Bland Altman showed a mean bias of 0.23° (95% CI: -0.16°, 0.63°) and 0.21° (95% CI: -0.3°, 0.73°). Accuracy and drift tests against constant standardised rotational velocities showed no drift behaviour over time, but RA estimation accuracy is reduced with increasing angular velocities (SD @ ±300°/s: 0.57°, max. difference from average at ±300°/s: 2.7°). During skiing on a ski ergometer the comparison of maximum RA against Vicon showed a mean bias of 0.13° (95% CI: -0.86° to 1.1°). Even though ski ergometer skiing has a similar frequency and angular velocity profile like outdoor skiing, there are more rotational degrees of freedom in outdoor skiing. The foundation is provided in this paper. To understand how a skier manipulates the ski on snow and to understand RA and EA progression during a turn in detail, further research should validate the method in the field and additionally look into RA progression within individual turns.
滑雪板与雪的相互作用是高山滑雪的重要组成部分。为了了解滑雪者如何操纵滑雪板转弯，我们需要开发出测量滑雪板在整个滑行过程中方向的方法。我们介绍并验证了如何校准和使用 IMU 来精确测量滚动角（RA）的方法，这是滑雪过程中滑雪板围绕其纵轴在三维空间中改变方向的问题：RMSE = 0.18°和 0.24°。Bland Altman 显示平均偏差为 0.23°（95% CI：-0.16°, 0.63°）和 0.21°（95% CI：-0.3°, 0.73°）。针对恒定标准化旋转速度进行的精度和漂移测试表明，随着时间的推移没有漂移行为，但 RA 估计精度会随着角速度的增加而降低（±300°/秒时的 SD：0.57°，±300°/秒时与平均值的最大差异：2.7°）。在滑雪测力计上滑雪时，最大 RA 与 Vicon 的比较显示平均偏差为 0.13°（95% CI：-0.86° 至 1.1°）。本文提供了相关基础。要想了解滑雪者如何在雪地上操控滑雪板，并详细了解转弯过程中的 RA 和 EA 进展，进一步的研究应在现场对该方法进行验证，并对单个转弯过程中的 RA 进展进行研究。
{"title":"Estimating ski orientation using IMUs in alpine skiing","authors":"Chris Hummel, Andreas Huber, Peter Spitzenpfeil","doi":"10.36950/2024.3ciss004","DOIUrl":"https://doi.org/10.36950/2024.3ciss004","url":null,"abstract":"Ski-snow interaction is the essential component of alpine skiing. To understand how a skier manipulates his ski to turn, we need to develop methods to measure the orientation of the ski throughout a complete run. Recent studies tried to use IMUs to estimate edge angle (EA) during skiing.\u0000We introduce and validate a method on how to calibrate and employ IMUs to precisely and accurately measure roll angles (RA) as a matter of changing orientation of the ski around its longitudinal axis in 3D space during skiing.\u0000Static orientation measurements on an inclined plane perfectly correlate (r2 = 1) with 3D motion capturing: RMSE = 0.18° and 0.24° respectively. Bland Altman showed a mean bias of 0.23° (95% CI: -0.16°, 0.63°) and 0.21° (95% CI: -0.3°, 0.73°). Accuracy and drift tests against constant standardised rotational velocities showed no drift behaviour over time, but RA estimation accuracy is reduced with increasing angular velocities (SD @ ±300°/s: 0.57°, max. difference from average at ±300°/s: 2.7°). During skiing on a ski ergometer the comparison of maximum RA against Vicon showed a mean bias of 0.13° (95% CI: -0.86° to 1.1°).\u0000Even though ski ergometer skiing has a similar frequency and angular velocity profile like outdoor skiing, there are more rotational degrees of freedom in outdoor skiing. The foundation is provided in this paper. To understand how a skier manipulates the ski on snow and to understand RA and EA progression during a turn in detail, further research should validate the method in the field and additionally look into RA progression within individual turns.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"81 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141021310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kelly Lockwood, Tzu-Ting Hsu, Colin Dunne, John-Allan Ellingson
Laces have traditionally been used to secure the foot, limit slippage, enhance fit, and prevent injury across different types of footwear. Quantitatively assessing the merits and effectiveness of laces is technically challenging due to the lack of portable instrumentation that can measure lace tension reliably. Therefore, the purpose of the study was to design and build a portable apparatus to quantify lace tension to be used on footwear in both laboratory and real-world environments. The apparatus was designed to meet three major design criteria: (i) portable, (ii) able to accommodate different types of footwear, lace materials, and lacing patterns, and (iii) able to measure lace tension while the footwear is secured on the foot. As a result of the design process, the apparatus consisted of a base, fabricated from High Density Polyethylene (HDPE), and a frame, made from aluminum and 3D printed Acrylonitrile Butadiene Styrene (ABS). A measurement system was affixed to the frame and consisted of a lever, a non-deformable cable with a hook, a load cell, a caliper, and a microcontroller to measure the force and change in length of laces when a force was applied. The total height and weight of the apparatus was 25.5 cm and 6.35 kg, respectively. A reliability analysis was conducted using three different types of laces (waxed, non-waxed, and carbon fiber blend) and revealed a high internal consistency within lace types with alpha values of 0.95, 0.81, 0.91, respectively. The interclass reliability coefficient across lace types revealed an alpha value of 0.84. As a result of the design, build, and reliability analysis, the apparatus was able to provide reliable measurements of lace tension while satisfying the design criteria. It is envisioned that the apparatus can be used for ongoing investigations across different types of footwear and different types of laces.
{"title":"Design and build of a portable apparatus for measuring lace tension","authors":"Kelly Lockwood, Tzu-Ting Hsu, Colin Dunne, John-Allan Ellingson","doi":"10.36950/2024.3ciss009","DOIUrl":"https://doi.org/10.36950/2024.3ciss009","url":null,"abstract":"Laces have traditionally been used to secure the foot, limit slippage, enhance fit, and prevent injury across different types of footwear. Quantitatively assessing the merits and effectiveness of laces is technically challenging due to the lack of portable instrumentation that can measure lace tension reliably. Therefore, the purpose of the study was to design and build a portable apparatus to quantify lace tension to be used on footwear in both laboratory and real-world environments. The apparatus was designed to meet three major design criteria: (i) portable, (ii) able to accommodate different types of footwear, lace materials, and lacing patterns, and (iii) able to measure lace tension while the footwear is secured on the foot. As a result of the design process, the apparatus consisted of a base, fabricated from High Density Polyethylene (HDPE), and a frame, made from aluminum and 3D printed Acrylonitrile Butadiene Styrene (ABS). A measurement system was affixed to the frame and consisted of a lever, a non-deformable cable with a hook, a load cell, a caliper, and a microcontroller to measure the force and change in length of laces when a force was applied. The total height and weight of the apparatus was 25.5 cm and 6.35 kg, respectively. A reliability analysis was conducted using three different types of laces (waxed, non-waxed, and carbon fiber blend) and revealed a high internal consistency within lace types with alpha values of 0.95, 0.81, 0.91, respectively. The interclass reliability coefficient across lace types revealed an alpha value of 0.84. As a result of the design, build, and reliability analysis, the apparatus was able to provide reliable measurements of lace tension while satisfying the design criteria. It is envisioned that the apparatus can be used for ongoing investigations across different types of footwear and different types of laces.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"27 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141022535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elite winter sports have become increasingly professionalized and commercialized, often accompanied by congested competition schedules. This has brought the topic of load management, i.e., planning, monitoring, and adaptation, enormous attention in the scientific community. In this review, we summarize the general knowledge from various sports about training load and its effects on injuries and illnesses. After outlining the fundamentals of load monitoring, we present common monitoring tools, i.e., neuromuscular performance tests, heart rate measures, blood-based biomarkers, and questionnaires and discuss their potentials and pitfalls in application. Studies have identified training load-related variables, but also other factors such as travelling, previous injuries, or age contributing to the occurrence of illness and injury. Based on our findings, the use of monitoring tools must be context-specific and long-term, considering statistical aspects as well. Promising study designs and future perspectives are finally highlighted, with the general conclusion that there is still a clear need for research on this topic in general and in the field of winter sports in particular.
{"title":"The puzzle of monitoring training load in winter sports - A hard nut to crack?","authors":"Nils Haller, Tilmann Strepp, T. Stöggl","doi":"10.36950/2024.3ciss008","DOIUrl":"https://doi.org/10.36950/2024.3ciss008","url":null,"abstract":"Elite winter sports have become increasingly professionalized and commercialized, often accompanied by congested competition schedules. This has brought the topic of load management, i.e., planning, monitoring, and adaptation, enormous attention in the scientific community. In this review, we summarize the general knowledge from various sports about training load and its effects on injuries and illnesses. After outlining the fundamentals of load monitoring, we present common monitoring tools, i.e., neuromuscular performance tests, heart rate measures, blood-based biomarkers, and questionnaires and discuss their potentials and pitfalls in application. Studies have identified training load-related variables, but also other factors such as travelling, previous injuries, or age contributing to the occurrence of illness and injury. Based on our findings, the use of monitoring tools must be context-specific and long-term, considering statistical aspects as well. Promising study designs and future perspectives are finally highlighted, with the general conclusion that there is still a clear need for research on this topic in general and in the field of winter sports in particular.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141022110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mediatization of communicative action is a process that centrally moderates social change. Changes in communication (e.g., through new kinds of media) thus have momentous consequences for social forms and processes. As essential cultural signs, social bodies, their medial representation, and areas of society in which bodies play a role are interrelated with changes in communication. Currently, physical self-representations in digital media play a key role and hold strong possibilities of influence on the culture of sports and movement. The aim of this study was to identify the effects of visual self-representations in social media on this culture. Following an integrative review methodology, we systematically organised the current state of empirical evidence and identified the implications that digital self-representations in social media (esp., Instagram, Facebook) have on sports and movement culture and therefore possibly on physical education (PE). Six electronic databases, reference lists, and citations of full-text articles were searched for English and German language peer-reviewed articles. The search string combined different terms relating to social media and sports culture. Two independent reviewers screened all identified studies for eligibility and assessed the methodological quality of the included studies. The results point to direct changes in some sports and movement cultures such as the prosumtion (consumption and production) of videos in skateboarding or the perpetuation of body ideals in the fitness culture. Other sports and movement cultures are changed indirectly via different new use cases for the athletes, as they can use social media to either build communities or gain visibility. As the practice of prosuming bodily self-representations is a growing part of the lifeworld of adolescents, such practices could become content within PE. Therewith, students could acquire competencies that allow them to intellectually relate to these practices, which could help them in understanding, changing or transcending their existing realities.
{"title":"#picturesofchange: Physical self-representations in social media as a sign of change in sports- and movement culture","authors":"Fabian Muhsal, David Jaitner, Jannika John","doi":"10.36950/2023.3ciss006","DOIUrl":"https://doi.org/10.36950/2023.3ciss006","url":null,"abstract":"The mediatization of communicative action is a process that centrally moderates social change. Changes in communication (e.g., through new kinds of media) thus have momentous consequences for social forms and processes. As essential cultural signs, social bodies, their medial representation, and areas of society in which bodies play a role are interrelated with changes in communication. Currently, physical self-representations in digital media play a key role and hold strong possibilities of influence on the culture of sports and movement. The aim of this study was to identify the effects of visual self-representations in social media on this culture. Following an integrative review methodology, we systematically organised the current state of empirical evidence and identified the implications that digital self-representations in social media (esp., Instagram, Facebook) have on sports and movement culture and therefore possibly on physical education (PE). Six electronic databases, reference lists, and citations of full-text articles were searched for English and German language peer-reviewed articles. The search string combined different terms relating to social media and sports culture. Two independent reviewers screened all identified studies for eligibility and assessed the methodological quality of the included studies. The results point to direct changes in some sports and movement cultures such as the prosumtion (consumption and production) of videos in skateboarding or the perpetuation of body ideals in the fitness culture. Other sports and movement cultures are changed indirectly via different new use cases for the athletes, as they can use social media to either build communities or gain visibility. As the practice of prosuming bodily self-representations is a growing part of the lifeworld of adolescents, such practices could become content within PE. Therewith, students could acquire competencies that allow them to intellectually relate to these practices, which could help them in understanding, changing or transcending their existing realities.","PeriodicalId":508861,"journal":{"name":"Current Issues in Sport Science (CISS)","volume":"13 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139525658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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