The purpose of the paper is to determine the differences in the technique of body inrun position at the beginning of take-off in junior ski jumpers of different qualifications (athletic ...preparedness).
Materials and methods. The study participants were 22 junior ski jumpers aged 14-15 (a group of junior ski jumpers) during the Ukrainian Ski Jumping Championship (October 9, 2010, Vorokhta, Ukraine) and 33 ski jumpers aged 16-17 (a group of senior ski jumpers) who took part in the international competitions “Lotos Cup” in January 2010. The study analyzed the videos of take-offs of 22 athletes aged 14-15 and 33 athletes aged 16-17. The parameters of ski jumping technique and sports results were processed on the basis of video materials of the first competition series.
Results. There are significant differences (p < 0.001) in the mean values of corresponding parameters of the body position at the beginning of take-off. The data point to a tighter tuck of the body of the athletes aged 16-17. The structure coefficients of the first canonical discriminant function indicate that the function is most significantly related to the values of angles 10 (ν); 8 (ζ); 6 (θ): the inclination angle of the segment of the straight line passing through the axes of the hip and ankle joints (ν) towards the direction of the skier’s movement; the inclination angle of the segment of the straight line passing through the general center of body weight and the axis of the ankle joint (ζ) towards the direction of the skier’s movement; the inclination angle of the head towards the trunk (θ). The athletes aged 16-17 differ from the athletes aged 14-15 by the parameters characterizing the body’s tuck in the starting position – the position at the beginning of take-off.
Conclusions. The unstandardized canonical discriminant function coefficients can be used to classify the levels of proficiency in the body’s tuck in the starting position – the position at the beginning of take-off in athletes aged 14-17.
The assumption that events can have positive economic impacts has increased interest in their hosting by many destinations worldwide. Although attendees are a constitutive part of events, scarce ...research has empirically analyzed their behavior from an economic standpoint. In particular,
further exploratory research is required on (1) how much money event attendees spend at events, and (2) the extent to which event attendee expenditures positively affect the host region. A better understanding of these two aspects is crucial for any kind of economic impact assessment. This
study examines three World Cup ski-jumping events in Norway during the winter of 2012-2013. Altogether, 870 spectators were interviewed at the venues in Vikersund, Trondheim, and Oslo. Prior research has estimated that the proportion of spectators contributing to a positive economic
impact is between 10% and 60%. The current study shows that the share of this spectator group at the World Cup ski-jumping events in Norway lies in the lower part of the range. Furthermore, the study shows that though the total number of spectators was significant (137,000), the primary economic
impact on the host region was modest, amounting to less than NOK 9 million.
With tracking systems becoming more widespread in sports research and regular training and competitions, more data are available for sports analytics and performance prediction. We analyzed 2523 ski ...jumps from 205 athletes on five venues. For every jump, the dataset includes the 3D trajectory, 3D velocity, skis’ orientation, and metadata such as wind, starting gate, and ski jumping hill data. Using this dataset, we aimed to predict the expected jump length (xLength) inspired by the expected goals metric in soccer (xG). We evaluate the performance of a fully connected neural network, a convolutional neural network (CNN), a long short-term memory (LSTM), and a ResNet architecture to estimate the xLength. For the prediction of the jump length one second after take-off, we achieve a mean absolute error (MAE) of 5.3 m for the generalization to new athletes and an MAE of 5.9 m for the generalization to new ski jumping hills using ResNet architectures. Additionally, we investigated the influence of the input time after the take-off on the predictions’ accuracy. As expected, the MAE becomes smaller with longer inputs. Due to the real-time transmission of the sensor’s data, xLength can be updated during the flight phase and used in live TV broadcasting. xLength could also be used as an analysis tool for experts to quantify the quality of the take-off and flight phases.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This paper deals with the development of a robust optimal control framework for a previously developed multi-body ski jumper simulation model by the authors. This framework is used to model ...uncertainties acting on the jumper during his jump, e.g., wind or mass, to enhance the performance, but also to increase the fairness and safety of the competition. For the uncertainty modeling the method of generalized polynomial chaos together with the discrete expansion by stochastic collocation is applied: This methodology offers a very flexible framework to model multiple uncertainties using a small number of required optimizations to calculate an uncertain trajectory. The results are then compared to the results of the Latin-Hypercube sampling method to show the correctness of the applied methods. Finally, the results are examined with respect to two major metrics: First, the influence of the uncertainties on the jumper, his positioning with respect to the air, and his maximal achievable flight distance are examined. Then, the results are used in a further step to quantify the safety of the jumper.
For sports scientists and coaches, its crucial to have reliable tracking systems to improve athletes. Therefore, this study aimed to examine the validity of a wearable real-time tracking system ...(WRRTS) for the quantification of ski jumping. The tracking system consists of wearable trackers attached to the ski bindings of the athletes and fixed antennas next to the jumping hill. To determine the accuracy and precision of the WRRTS, four athletes of the German A or B National Team performed 35 measured ski jumps. The WRRTS was used to measure the 3D positions and ski angles during the jump. The measurements are compared with camera measurements for the in-flight parameters and the official video distance for the jumping distance to assess their accuracy. We statistically evaluated the different methods using Bland–Altman plots. We thereby find a mean absolute error of 0.46 m for the jumping distance, 0.12 m for the in-flight positions, and 0.8°, and 3.4° for the camera projected pitch and V-style opening angle, respectively. We show the validity of the presented WRRTS to measure the investigated parameters. Thus, the system can be used as a tracking system during training and competitions for coaches and sports scientists. The real-time feature of the tracking system enables usage during live TV broadcasting.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Ski jumping is a highly competitive sport, where the distance jumped is greatly dependent on the aerodynamic effects of the athlete’s posture. In the current paper a wind tunnel experiment was ...conducted to generate a parametric database of the effects of posture on aerodynamics and to compute the aerodynamic force coefficients. The parameters considered were varied over ranges representative of modern ski jumping and included the ski incidence angle, the ski V-angle, the leg-to-ski angle, and the hip angle. Measured force data were then used to simulate ski jumping flightpaths via a numerical model, allowing for the effects of posture on jump distance to be investigated. The model was able to simulate single and multi-posture flights to suggest both static and dynamic optimums. It was found that the ski jumping system generated lift in previously unreported, non-linear methods, enabling the flow to stay attached at much larger incidences than traditional wings. When optimizing posture for distance, it was found that neither lift nor efficiency (lift-to-drag ratio) should be maximized, due to the reliance on both qualities for a successful jump. However, when considering multi-posture flight, it was found that the lift-to-drag ratio should be maximized immediately after take-off, to maintain horizontal velocity. Lift should be maximized as the athlete approaches landing, due to the highly curved flightpath reducing the negative impact of drag. Realistic recommendations have been made on the postures that athletes should utilize to improve their performance. This includes a single position optimum, a “safe” optimum which allows some variation in an athlete’s ability to hold posture, and a further optimum should the athlete be skillful enough to dynamically alter posture as the jump progresses.
Wind conditions are well-known to affect results of ski jumping competitions. To alleviate effects of different head or tail winds and differences in inrun length due to jury or coaches' decisions, ...the FIS (F#233;deration Internationale de Ski) has adopted a wind and gate compensation system since January 2010. However, the accuracy and fairness of the resulting compensation points are often questioned by athletes, spectators, and media commentators alike but have not yet been thoroughly investigated. In the present meta-analysis, we present evidence for systematic negative associations of wind points but positive associations of gate points with round scores across all World Cup and World Championship competitions of men in the ski jumping seasons 2016/2017 and 2017/2018 (k = 35 and 30, respectively). Moreover, our results indicate that absolute correlations between wind points and round scores increased in presence of larger wind point variability, thus indicating lower accuracy of compensation systems when conditions are more variable. Additionally, there was a trend for larger wind point malcompensations on larger jumping hills. Our results suggest that the current wind point compensation formula as well as gate factors should be reevaluated to prevent systematically biased point awards within and across competitions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nordic ski athletes are at increased risk of developing hip pain and dysfunction secondary to femoroacetabular impingement syndrome (FAIS), but it is unclear whether hip symptomatology differs ...between ski jumping (SJ) and Nordic combined (NC) athletes. The purpose of this study was to compare patient-reported hip pain and dysfunction between elite Nordic ski athletes participating in SJ versus NC.
A cross-sectional study was conducted involving SJ and NC athletes who competed at the international and U.S. national levels during the 2021–2022 season. Subjects were excluded if they had hip surgery within two years prior to enrollment. Subjects were asked to undergo diagnostic workups for FAIS, including physical examination and plain radiographic imaging. Subjects were asked to complete a survey that collected information on athletic and training history and to complete the hip disability and osteoarthritis outcome score (HOOS). Demographics, athletic/training history, and HOOS sub-scores were compared between the SJ and NC groups using the Student's t-test, Wilcoxon rank-sum test, or Fisher's exact test, as appropriate. p-values < 0.05 were considered significant.
Twenty-four athletes (13 SJ, 11 NC) were included in the study. There were no statistically significant differences in age, sex, BMI, or age of menarche between the two groups (all p > 0.05). There were also no statistically significant differences in the number of prior sports participated in, total hours of participation in prior sports, or total hours of training in Nordic specialization (all p > 0.05). Among the 18 athletes who underwent physical examination (9 SJ, 9 NC), there were no statistically significant inter-group differences in hip range of motion or incidence of positive impingement tests (all p > 0.05). Among the 19 athletes who underwent imaging (9 SJ, 10 NC), there were no statistically significant inter-group differences in the incidence of cam or pincer morphology in at least one hip (all p > 0.05). SJ athletes had statistically significantly worse HOOS sub-scores for hip symptoms and stiffness, hip function in sports/recreational activities, and hip-related quality of life compared to NC athletes (all p < 0.05).
Elite SJ athletes have worse self-reported hip function compared to elite NC athletes, despite comparable demographics, athletic history, and duration of ski training.
IV.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In 2023, for the first time in history, the international ski and snowboard federation (FIS) arranged an official ski flying competition where the 15 highest ranked women were allowed to participate. ...This study investigated jump-to-jump performance development in female ski flying, with men's results used as reference data. Official FIS data from all six jumps of women were evaluated together with the eight jumps by men. Performance was evaluated by a score, where the distance points compensated by wind were divided by take-off speed, enabling performance to be evaluated across jumps and sexes. Women improved performance by 96% from the first to the sixth jump, with two major leaps; from the first to the second jump and from the first to the second day. In contrast, men mainly improved from training to competition. The best women had performance scores equivalent to the 10-20 best ranked men and the sex-difference between the top 3 athletes was 26.2%. This difference was thereafter compared to similar results in the normal and large hill World championship in Planica 2023, in which sex-differences between the top 3 were 8.6% and 14.6% in normal and large hill. This historical competition showed the importance of gaining practical experience with ski flying on performance, exemplified by the large improvement of female athletes. This, together with the enlarge sex-differences in large compared to normal hills, indicates that female ski jumpers have a particularly large improvement-potential in ski flying and must gain specific experience on this through traning and competitions.
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