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Article

Kinematic Determination of the Aerial Phase in Ski Jumping

1
Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
2
Norwegian Olympic and Paralympic Committee and Confederation of Sports, 0863 Oslo, Norway
3
Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway
4
Department of Physical Performance, Norwegian School of Sport Sciences, 0863 Oslo, Norway
5
Center of Alpine Sports Biomechanics, Engadin Health and Innovation Foundation, 7503 Samedan, Switzerland
*
Author to whom correspondence should be addressed.
Academic Editors: Darren Stefanyshyn and Christian Clermont
Sensors 2022, 22(2), 540; https://doi.org/10.3390/s22020540
Received: 22 November 2021 / Revised: 5 January 2022 / Accepted: 8 January 2022 / Published: 11 January 2022
(This article belongs to the Special Issue Wearable Sensors for Biomechanical Monitoring in Sport)
The purpose of this study was to find a generic method to determine the aerial phase of ski jumping in which the athlete is in a steady gliding condition, commonly known as the ‘stable flight’ phase. The aerial phase of ski jumping was investigated from a physical point mass, rather than an athlete–action-centered perspective. An extensive data collection using a differential Global Navigation Satellite System (dGNSS) was carried out in four different hill sizes. A total of 93 jumps performed by 19 athletes of performance level, ranging from junior to World Cup, were measured. Based on our analysis, we propose a generic algorithm that identifies the stable flight based on steady glide aerodynamic conditions, independent of hill size and the performance level of the athletes. The steady gliding is defined as the condition in which the rate-of-change in the lift-to-drag-ratio (LD-ratio) varies within a narrow band-width described by a threshold τ. For this study using dGNSS, τ amounted to 0.01s−1, regardless of hill size and performance level. While the absolute value of τ may vary when measuring with other sensors, we argue that the methodology and algorithm proposed to find the start and end of a steady glide (stable flight) could be used in future studies as a generic definition and help clarify the communication of results and enable more precise comparisons between studies. View Full-Text
Keywords: ski jumping; dGNSS; LD-ratio; stable flight; steady glide ski jumping; dGNSS; LD-ratio; stable flight; steady glide
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MDPI and ACS Style

Elfmark, O.; Ettema, G.; Jølstad, P.; Gilgien, M. Kinematic Determination of the Aerial Phase in Ski Jumping. Sensors 2022, 22, 540. https://doi.org/10.3390/s22020540

AMA Style

Elfmark O, Ettema G, Jølstad P, Gilgien M. Kinematic Determination of the Aerial Phase in Ski Jumping. Sensors. 2022; 22(2):540. https://doi.org/10.3390/s22020540

Chicago/Turabian Style

Elfmark, Ola, Gertjan Ettema, Petter Jølstad, and Matthias Gilgien. 2022. "Kinematic Determination of the Aerial Phase in Ski Jumping" Sensors 22, no. 2: 540. https://doi.org/10.3390/s22020540

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