Assessment of the steady glide phase in ski jumping

Elfmark, Ola; Ettema, Gertjan; Gilgien, Matthias

doi:10.1016/j.jbiomech.2022.111139

Cited by 7 publications

(20 citation statements)

References 17 publications

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“…In contrast, ski jumping research on men dates back to 1926 ( 5 ) and has been a relatively popular scientific topic. The consensus in previous research is to split a ski jump into different phases (inrun, take-off, glide preparation, steady glide, landing preparation and landing phase) where the take-off phase is considered to be most important for performance ( 6 , 7 ). However, larger hill sizes, higher competition speeds and longer aerial times have made manipulation of aerodynamic forces more important and extensively investigated in previous years ( 6 – 12 ).…”

Section: Introductionmentioning

confidence: 99%

“…The consensus in previous research is to split a ski jump into different phases (inrun, take-off, glide preparation, steady glide, landing preparation and landing phase) where the take-off phase is considered to be most important for performance ( 6 , 7 ). However, larger hill sizes, higher competition speeds and longer aerial times have made manipulation of aerodynamic forces more important and extensively investigated in previous years ( 6 – 12 ). The aerodynamic forces are deemed to be particularly influential in SF, which is a competition form rarely mentioned in the scientific literature ( 13 , 14 ).…”

Section: Introductionmentioning

confidence: 99%

“…Hill size influences the key features associated with ski jumping performance which may also affect male and female ski jumpers differently. Elfmark et al ( 6 ) found that clear differences exist between the NH and LH regarding the influence of key variables in the aerial phase. In the NH, performance was found to be largely determined by the take-off and glide preparation, while the steady glide (especially having a high ratio between aerodynamic lift and aerodynamic drag) was found to be as important as the take-off in the LH.…”

Section: Introductionmentioning

confidence: 99%

“…In the NH, performance was found to be largely determined by the take-off and glide preparation, while the steady glide (especially having a high ratio between aerodynamic lift and aerodynamic drag) was found to be as important as the take-off in the LH. The factors of importance in a LH are assumed to be of even higher importance in a SF, where the aerial time is around 8 s compared to 4 s in a LH ( 6 ). Women mainly compete in NH (61–77% of competitions in the two previous seasons) while men almost exclusively (>90% of competitions) compete in LH and SF.…”

Section: Introductionmentioning

confidence: 99%

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Performance and jump-to-jump development in the first female ski flying competition in history

Elfmark,

Sandbakk,

Brevig

et al. 2024

Front. Sports Act. Living

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Performance and jump-to-jump development in the first female ski flying competition in history

Elfmark,

Sandbakk,

Brevig

et al. 2024

Front. Sports Act. Living

Self Cite

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“…Elfmark et al [ 20 ] use a differential Global Navigation Satellite System (dGNSS) and video-based pose estimation for performance analysis in ski jumping. They also use the data collected with the dGNSS to determine the aerial phase in ski jumping [ 21 ] and assess the steady glide phase [ 22 ]. Camera-based tracking was also widely used in ski jumping studies to analyze the take-off [ 23 , 24 ], flight styles [ 25 ], ski jumping phases [ 26 , 27 , 28 ], dynamics [ 29 ], and aerodynamic forces [ 30 ].…”

Section: Introductionmentioning

confidence: 99%

xLength: Predicting Expected Ski Jump Length Shortly after Take-Off Using Deep Learning

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Schwinn²,

Pulsmeyer³

et al. 2022

Sensors

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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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Investigation of individual strategies in the aerial phase in ski jumping

Jølstad,

Gilgien,

Elfmark

2023

Sci Rep

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The purpose of this investigation was to examine the performance strategy of three ski jumpers during the steady glide phase and explain how different strategical solutions can lead to jumps of roughly the same length. In this study, a total of 24 jumps performed by two World Cup (WC) athletes and one Continental Cup (COC) athlete were measured with a differential Global Navigation Satellite System (dGNSS) on a large ski jumping hill. For each athlete, the continuous position data, velocity, aerodynamic forces and lift-to-drag ratio (LD-ratio) were averaged and compared for the steady glide phase to examine individual jump strategies. The dGNSS yielded accurate measurements of trajectory, velocity and aerodynamic forces, revealing clear differences between the athletes. The largest differences were found between the WC athletes and the COC athlete. The WC athletes focused on maximizing horizontal velocity while the COC athlete minimized vertical velocity. This difference may be explained by the different hill sizes the athletes normally compete on. One of the WC athletes consistently increased their horizontal velocity during the end of the steady glide phase by maintaining a high LD-ratio, which highlights the effect of aerodynamics on the resulting velocity, trajectory and jump length.

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Assessment of the steady glide phase in ski jumping

Cited by 7 publications

References 17 publications

Performance and jump-to-jump development in the first female ski flying competition in history

Performance and jump-to-jump development in the first female ski flying competition in history

xLength: Predicting Expected Ski Jump Length Shortly after Take-Off Using Deep Learning

Investigation of individual strategies in the aerial phase in ski jumping

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