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Yanaka T, Nakamura M, Yamanobe K, Ishige Y. Changes in roller skiing economy among Nordic combined athletes leading up to the competition season. Front Sports Act Living 2024; 6:1320698. [PMID: 38500548 PMCID: PMC10944959 DOI: 10.3389/fspor.2024.1320698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 02/21/2024] [Indexed: 03/20/2024] Open
Abstract
The purpose of this study was to compare roller skiing economy during different training phases in Nordic combined (NC) athletes and determine the aerobic and anaerobic factors responsible for changes in skiing economy. Seven elite NC athletes underwent incremental load tests on a large buried treadmill in both spring and autumn using roller skis. Measurements included oxygen uptake, respiratory exchange ratio, and blood lactate concentration. Roller skiing economy was calculated from aerobic and anaerobic energy system contributions, and overall roller skiing economy was determined by combining the two. Comparisons were made between the skiing economies obtained in the two measurement sessions. Physical characteristics and incremental test performance remained consistent between the two measurement sessions. The overall skiing economy at each speed significantly improved toward the competition season (p < 0.05). Similarly, the contribution of anaerobic energy system at each speed showed significant improvement (p < 0.05). In contrast, the contribution of aerobic energy system did not change between the two measurement sessions. This study reveals that NC athletes enhance their skiing economy at the same speed during submaximal efforts in preparation for the competition season. This improvement is predominantly associated with an improvement in the contribution of anaerobic energy system.
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Affiliation(s)
- Takuya Yanaka
- Department of Sports Science and Research, Japan Institute of Sports Sciences, Tokyo, Japan
- Faculty of Commerce, Yokohama College of Commerce, Kanagawa, Japan
| | - Mariko Nakamura
- Department of Sports Science and Research, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Kaoru Yamanobe
- Department of Sports Science and Research, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Yusuke Ishige
- Department of Sports Science and Research, Japan Institute of Sports Sciences, Tokyo, Japan
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Oronowicz J, Seil R, Hörterer H, Moksnes H, Ekas GR, Cabri J, Mouton C, Frenzel G, Tischer T. Anterior cruciate ligament injuries in elite ski jumping reliably allow return to competition but severely affect future top performance. Knee Surg Sports Traumatol Arthrosc 2024; 32:616-622. [PMID: 38363010 DOI: 10.1002/ksa.12076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 01/25/2024] [Indexed: 02/17/2024]
Abstract
PURPOSE In recent years, anterior cruciate ligament (ACL) injuries have been frequently observed in ski jumping. However, available data in this discipline are very scarce. Therefore, the purpose of this study was to investigate whether an ACL injury in elite-level ski jumping limits the performance level after ACL reconstruction (ACLR). METHODS Both male and female elite-level ski jumpers from five national A-teams who suffered an ACL injury were identified retrospectively by searching available media reports and Fédération Internationale de Ski (FIS) database. World Cup (WC) results and time-out-of-competition before ACL injury and after ACLR were compared. Only athletes who suffered the injury during or after the 2009-2010 season and who participated in at least one WC competition before the injury were included in this study. The level of athletes' performance from two full seasons before until three seasons after the injury was compared. RESULTS Eighteen elite-level ski jumpers (11 males/seven females) were eligible for the study. All male and four female athletes returned to professional competition after ACLR. One female athlete ended her career due to prolonged recovery and two have not yet recovered due to a recent injury. The mean return-to-competition (RTC) time was 14.6 months in males and 13.5 months in females. The mean WC placement decreased after the ACL injury: two seasons before injury the mean position was 17.9 ± 11.0 (n = 12), one season before it was 22.4 ± 12.8 (n = 15). After recovery, the mean placement in seasons 1-3 was: 26.4 ± 8.9 (n = 7), 25.7 ± 10.3 (n = 13), 33.6 ± 12.2 (n = 10) (p = 0.008). Among the athletes returning to competition, only six males and three females reached their preinjury level and only one male and one female (compared to seven males and three females preinjury) reached an individual top-3 placement after ACLR, accounting for less than 10% of podiums compared to preinjury. CONCLUSION Only 60% of the professional ski jumpers reached the preinjury level and less than 15% reached a top-3 placement after the ACL injury. These results support the fact that ACL tear during a ski jumping career may be a significant factor limiting high-level performance. In terms of clinical relevance, the findings implicate the need to analyse the reasons of these very low rates of return to elite-level performance, to analyse ACL injury and RTC rates at lower levels of performance and to develop specific prevention strategies in order to reduce the number of ACL injuries in this sport. LEVEL OF EVIDENCE Level IV.
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Affiliation(s)
- Jakub Oronowicz
- Clinic for Orthopaedics and Trauma Surgery, Malteser St. Mary's Hospital, Erlangen, Germany
| | - Romain Seil
- Department of Orthopaedic Surgery, Centre Hospitalier de Luxembourg (CHL)-Clinique d'Eich, Luxembourg City, Luxembourg
- Luxembourg Institute of Research in Orthopaedics, Sports Medicine and Science (LIROMS), Luxemburg City, Luxembourg
- Human Motion, Orthopaedics, Sports Medicine and Digital Methods (HOSD), Luxembourg Institute of Health (LIH), Luxembourg City, Luxembourg
| | - Hubert Hörterer
- Chairman Medical Committee FIS; Member Competition Equipment Committee FIS, Rottach-Egern, Bayern, Germany
| | - Håvard Moksnes
- Oslo Sports Trauma Research Centre, Norwegian School of Sport Sciences, Oslo, Norway
| | - Guri R Ekas
- Oslo Sports Trauma Research Centre, Norwegian School of Sport Sciences, Oslo, Norway
- Orthopaedic Department, Akershus University Hospital, Nordbyhagen, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Team Physician, Ski Jumping, Norwegian Ski Federation, Oslo, Norway
| | - Jan Cabri
- Luxembourg Institute of Research in Orthopaedics, Sports Medicine and Science (LIROMS), Luxemburg City, Luxembourg
- Faculty of Medicine and Pharmacy, GERO, Vrije Universiteit Brussel, Brussels, Belgium
| | - Caroline Mouton
- Department of Orthopaedic Surgery, Centre Hospitalier de Luxembourg (CHL)-Clinique d'Eich, Luxembourg City, Luxembourg
- Luxembourg Institute of Research in Orthopaedics, Sports Medicine and Science (LIROMS), Luxemburg City, Luxembourg
| | | | - Thomas Tischer
- Clinic for Orthopaedics and Trauma Surgery, Malteser St. Mary's Hospital, Erlangen, Germany
- Department of Orthopaedics, University of Rostock, Rostock, Germany
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Huang Y, Jiang L, Chen X, Sun Q, Zhang X, Tan X, Du Y, Zhang F, Wang N, Su R, Qu F, Zhang G, Huo B. Musculoskeletal simulation of professional ski jumpers during take-off considering aerodynamic forces. Front Bioeng Biotechnol 2023; 11:1241135. [PMID: 37720321 PMCID: PMC10501566 DOI: 10.3389/fbioe.2023.1241135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/21/2023] [Indexed: 09/19/2023] Open
Abstract
Introduction: Musculoskeletal simulation has been widely used to analyze athletes' movements in various competitive sports, but never in ski jumping. Aerodynamic forces during ski jumping take-off have been difficult to account for in dynamic simulation. The purpose of this study was to establish an efficient approach of musculoskeletal simulation of ski jumping take-off considering aerodynamic forces and to analyze the muscle function and activity. Methods: Camera-based marker-less motion capture was implemented to measure the take-off kinematics of eight professional jumpers. A suitable full-body musculoskeletal model was constructed for the simulation. A method based on inverse dynamics iteration was developed and validated to estimate the take-off ground reaction force. The aerodynamic forces, which were calculated based on body kinematics and computational fluid dynamics simulations, were exerted on the musculoskeletal model as external forces. The activation and joint torque contributions of lower extremity muscles were calculated through static optimization. Results: The estimated take-off ground reaction forces show similar trend with the results from past studies. Although overall inconsistencies between simulated muscle activation and EMG from previous studies were observed, it is worth noting that the activation of the tibialis anterior, gluteus maximus, and long head of the biceps femoris was similar to specific EMG results. Among lower extremity extensors, soleus, vastus lateralis, biceps femoris long head, gluteus maximus, and semimembranosus showed high levels of activation and joint extension torque contribution. Discussion: Results of this study advanced the understanding of muscle action during ski jumping take-off. The simulation approach we developed may help guide the physical training of jumpers for improved take-off performance and can also be extended to other phases of ski jumping.
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Affiliation(s)
- Yi Huang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Liang Jiang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Xue Chen
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Qing Sun
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Xiao Zhang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Xunan Tan
- Biomechanics Laboratory, Beijing Sport University, Beijing, China
| | - Yan Du
- Biomechanics Laboratory, Beijing Sport University, Beijing, China
| | - Fangtong Zhang
- Biomechanics Laboratory, Beijing Sport University, Beijing, China
| | - Nannan Wang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Rufeng Su
- Institute of Artificial Intelligence in Sports, Capital University of Physical Education and Sports, Beijing, China
| | - Feng Qu
- Biomechanics Laboratory, Beijing Sport University, Beijing, China
| | - Guoqing Zhang
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, China
| | - Bo Huo
- Institute of Artificial Intelligence in Sports, Capital University of Physical Education and Sports, Beijing, China
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Rotllan C, Viscor G. Winter Sports Injuries in Elite Female Athletes: A Narrative Review. Int J Environ Res Public Health 2023; 20:ijerph20105815. [PMID: 37239544 DOI: 10.3390/ijerph20105815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023]
Abstract
There is a lack of reviews covering the topic of the parallel high prevalence of injuries in female winter sport elite athletes. We aimed to review the data on incidence and patterns of injuries in female athletes participating in official competitions of winter sports. We conducted a comprehensive literature search on epidemiological data and etiological information on alpine skiing, snowboarding, ski jumping and cross-country skiing. The most common location of injury was the knee among skiers and ski jumpers and the incidence of severe ACL events was 7.6 per 100 ski racers per season (95% CI 6.6 to 8.9) in female alpine skiers. Snowboarders and cross-country skiers were more affected in the ankle and the foot. The most common cause was contact trauma with stagnant objects. The injury risk factors include training volume, knee pre-injuries, the period of the season and the technical equipment. Females are at greater risk of suffering from overuse injuries during the competitive season, as opposed to male athletes who are more likely to suffer from traumatic injuries. Our findings can be used to inform coaches and athletes and to guide future injury prevention plans.
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Affiliation(s)
- Cristina Rotllan
- Secció de Fisiologia, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Ginés Viscor
- Secció de Fisiologia, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
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Nam Y, Do Y, Kim J, Lee H, Kim DN. A hybrid framework to predict ski jumping forces by combining data-driven pose estimation and model-based force calculation. Eur J Sport Sci 2023; 23:221-230. [PMID: 35001852 DOI: 10.1080/17461391.2022.2028013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this paper is to propose a hybrid framework that combines a data-driven pose estimation with model-based force calculation in order to predict the ski jumping force from a recorded motion video. A skeletal model consisting of five joints (ear, hip, knee, ankle, and toe) and four rigid segments (head/arm/trunk or HAT, thigh, shank, and foot) connecting each joint is developed. The joint forces are calculated from the dynamic equilibrium equations, which requires the time history of joint coordinates. They are estimated from a recorded motion video using a deep neural network for pose estimation trained with human motion data. Joint coordinates can be obtained by the proposed deep neural network directly from images of jumping motion without using any markers. The validity and usefulness of the proposed method are confirmed in lab experiments. Further, our method is practically applicable to the study in a real competition environment because it is not required to attach any sensor or marker to athletes.Highlights A method to predict the ski jumping force from a recorded motion video is proposed.It combines a data-driven pose estimation with a model-based force calculation.The proposed method does not require any markers and sensors to be attached to athletes.In a laboratory environment, the relative error in the maximum jumping force is less than 7%.The method can be easily applied to a field study in a real competition environment.
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Affiliation(s)
- Yunhyoung Nam
- Department of Mechanical Engineering, Seoul National University, Seoul, Korea
| | - Youngkyung Do
- Department of Mechanical Engineering, Seoul National University, Seoul, Korea
| | - Jaehoon Kim
- Department of Mechanical Engineering, Seoul National University, Seoul, Korea
| | - Heonyong Lee
- Department of Mechanical Engineering, Seoul National University, Seoul, Korea
| | - Do-Nyun Kim
- Department of Mechanical Engineering, Seoul National University, Seoul, Korea.,Institute of Advanced Machines and Design, Seoul National University, Seoul, Korea.,Institute of Engineering Research, Seoul National University, Seoul, Korea
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Yamamoto K, Nishino T, Bale R, Shimada T, Miyamoto N, Tsubokura M. Numerical study of transient aerodynamic forces acting on a ski jumper considering dynamic posture change from takeoff to landing. Sports Biomech 2022:1-15. [PMID: 36510445 DOI: 10.1080/14763141.2022.2154256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022]
Abstract
This study was designed to develop a computational fluid dynamics (CFD) method for unsteady analysis of a series of ski jump movements with attitude changes, and to analyse the aerodynamic characteristics of an expert jumper over the entire ski jump movement. Two ski jumpers participated in this study. A sensor-based motion capture suit was used to capture the jumper's posture during the actual ski jump. A three-dimensional computer graphics animation was created by superimposing the joint angles obtained from the motion measurements of the 3D shape of the athlete. The unsteady aerodynamic forces acting on the ski jumper, from the takeoff to the landing, were then calculated using CFD. A time-varying spatially uniform flow was specified as the inflow boundary condition of the computational domain. The results indicated that both the lift and drag forces of the expert jumper increase rapidly during the initial flight when the jumper's posture changes drastically. Thereafter, drag force decreased considerably, but the decrease in the lift force was less drastic. Later in the flight phase, the lift force acting on the expert jumper increased, and throughout the flight phase, the lift-drag ratio of the expert jumper remained higher than that of the unskilled jumper.
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Affiliation(s)
- Keizo Yamamoto
- School of Lifelong Sport, Hokusho University, Ebetsu, Japan
| | - Takahiro Nishino
- Graduate School of System Informatics, Kobe University, Kobe, Japan
| | - Rahul Bale
- Complex Phenomena Unified Simulation Research Team, RIKEN Advanced Institute for Computational Science, Kobe, Japan
| | - Tokimasa Shimada
- Graduate School of System Informatics, Kobe University, Kobe, Japan
| | - Naoto Miyamoto
- New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan
| | - Makoto Tsubokura
- Graduate School of System Informatics, Kobe University, Kobe, Japan
- Complex Phenomena Unified Simulation Research Team, RIKEN Advanced Institute for Computational Science, Kobe, Japan
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Elfmark O, Ettema G, Jølstad P, Gilgien M. Kinematic Determination of the Aerial Phase in Ski Jumping. Sensors (Basel) 2022; 22:540. [PMID: 35062498 DOI: 10.3390/s22020540] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/05/2022] [Accepted: 01/08/2022] [Indexed: 12/04/2022]
Abstract
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.
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Prieske O, Chaabene H, Kullmann N, Granacher U. Effects of Individualized Versus Traditional Power Training on Strength, Power, Jump Performances, and Body Composition in Young Male Nordic Athletes. Int J Sports Physiol Perform 2022;:1-8. [PMID: 34983022 DOI: 10.1123/ijspp.2021-0074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 07/22/2021] [Accepted: 08/16/2021] [Indexed: 11/18/2022]
Abstract
PURPOSE This study aimed to examine the effects of individualized-load power training (IPT) versus traditional moderate-load power training (TPT) on strength, power, jump performance, and body composition in elite young Nordic athletes. METHODS In a randomized crossover design, 10 young male athletes (ski jumpers, Nordic combined athletes) age 17.5 (0.6) years (biological maturity status: +3.5 y postpeak height velocity) who competed on a national or international level performed 5 weeks of IPT (4 × 5 repetitions at 49%-72% 1-repetiton maximum [RM]) and TPT (5 × 5 repetitions at 50%-60% 1-RM) in addition to their regular training. Testing before, between, and after both training blocks comprised the assessment of muscle strength (loaded back squat 3-RM), power (maximal loaded back squat power), jump performance (eg, drop-jump height, reactive strength index), and body composition (eg, skeletal muscle mass). RESULTS Significant, large-size main effects for time were found for muscle strength (P < .01; g = 2.7), reactive strength index (P = .03; g = 1.6), and drop-jump height (P = .02; g = 1.9) irrespective of the training condition (IPT, TPT). No significant time-by-condition interactions were observed. For measures of body composition, no significant main effects of condition and time or time-by-condition interactions were found. CONCLUSIONS Our findings demonstrate that short-term IPT and TPT at moderate loads in addition to regular training were equally effective in improving measures of muscle strength (loaded back squat 3-RM) and vertical-jump performance (reactive strength index, drop jump, and height) in young Nordic athletes.
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Link J, Guillaume S, Eskofier BM. Experimental Validation of Real-Time Ski Jumping Tracking System Based on Wearable Sensors. Sensors (Basel) 2021; 21:7780. [PMID: 34883784 DOI: 10.3390/s21237780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/15/2021] [Accepted: 11/19/2021] [Indexed: 11/24/2022]
Abstract
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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Elfmark O, Ettema G, Groos D, Ihlen EAF, Velta R, Haugen P, Braaten S, Gilgien M. Performance Analysis in Ski Jumping with a Differential Global Navigation Satellite System and Video-Based Pose Estimation. Sensors (Basel) 2021; 21:5318. [PMID: 34450758 PMCID: PMC8399095 DOI: 10.3390/s21165318] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 11/16/2022]
Abstract
This study investigated the explanatory power of a sensor fusion of two complementary methods to explain performance and its underlying mechanisms in ski jumping. A differential Global Navigation Satellite System (dGNSS) and a markerless video-based pose estimation system (PosEst) were used to measure the kinematics and kinetics from the start of the in-run to the landing. The study had two aims; firstly, the agreement between the two methods was assessed using 16 jumps by athletes of national level from 5 m before the take-off to 20 m after, where the methods had spatial overlap. The comparison revealed a good agreement from 5 m after the take-off, within the uncertainty of the dGNSS (±0.05m). The second part of the study served as a proof of concept of the sensor fusion application, by showcasing the type of performance analysis the systems allows. Two ski jumps by the same ski jumper, with comparable external conditions, were chosen for the case study. The dGNSS was used to analyse the in-run and flight phase, while the PosEst system was used to analyse the take-off and the early flight phase. The proof-of-concept study showed that the methods are suitable to track the kinematic and kinetic characteristics that determine performance in ski jumping and their usability in both research and practice.
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Affiliation(s)
- Ola Elfmark
- Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
- Norwegian Olympic and Paralympic Committee and Confederation of Sports, 5000 Oslo, Norway;
| | - Gertjan Ettema
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway; (G.E.); (D.G.); (E.A.F.I.)
| | - Daniel Groos
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway; (G.E.); (D.G.); (E.A.F.I.)
| | - Espen A. F. Ihlen
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, 7491 Trondheim, Norway; (G.E.); (D.G.); (E.A.F.I.)
| | - Rune Velta
- Department of Physical Performance, Norwegian School of Sport Sciences, 4014 Oslo, Norway; (R.V.); (P.H.); (M.G.)
| | - Per Haugen
- Department of Physical Performance, Norwegian School of Sport Sciences, 4014 Oslo, Norway; (R.V.); (P.H.); (M.G.)
| | - Steinar Braaten
- Norwegian Olympic and Paralympic Committee and Confederation of Sports, 5000 Oslo, Norway;
| | - Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, 4014 Oslo, Norway; (R.V.); (P.H.); (M.G.)
- Center of Alpine Sports Biomechanics, Engadin Health and Innovation Foundation, 7503 Samedan, Switzerland
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Ketterer J, Gollhofer A, Lauber B. Biomechanical agreement between different imitation jumps and hill jumps in ski jumping. Scand J Med Sci Sports 2020; 31:115-123. [PMID: 32969534 DOI: 10.1111/sms.13834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/21/2020] [Accepted: 09/11/2020] [Indexed: 11/27/2022]
Abstract
Even though the take-off in ski jumping is decisive, athletes only have a very limited number of training trials on the actual ski jump to practice under real ski jump conditions. Hence, various imitation jumps aiming to mimic the hill jump are performed during daily training. These imitation jumps should therefore mimic the kinematic pattern of hill jumps appropriately. This study aimed to identify imitation jumps that resemble hill jumps regarding four performance-related biomechanical criteria: maximal vertical take-off velocity, maximal knee extension velocity, maximal forward-directed angular momentum and anterior shift of the center of mass. Therefore, a three-dimensional analysis of the take-off during six different modalities of imitation jumps as well as hill jumps for validation was carried out in nine professional ski jumpers. Imitation jumps from a rolling platform show better agreement than stationary jumps and three out of the four parameters were best resembled via an imitation jump that included ski jumping boots. Thus, non-hill take-off training should be performed with complex imitation jumps to mimic the actual ski jump. Except for the vertical take-off velocity, we could identify one imitation jump type that is not statistically different to the hill. Consequently, the individual deficiencies of the athletes can be addressed and specifically trained using the appropriate imitation jump. These information about the similarity between imitation jumps and real hill jumps are highly relevant for trainers and athletes in order to effectively design their training programs.
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Affiliation(s)
- Jakob Ketterer
- Department of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Albert Gollhofer
- Department of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Benedikt Lauber
- Department of Sport and Sport Science, University of Freiburg, Freiburg, Germany.,Department of Neurosciences and Movement Sciences, University of Fribourg, Fribourg, Switzerland
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Stenseth OMR, Barli SF, Martin RK, Engebretsen L. Injuries in elite women's ski jumping: surveillance through the 2017-18 FIS World Cup season. Br J Sports Med 2019; 54:44-48. [PMID: 31527043 PMCID: PMC6923946 DOI: 10.1136/bjsports-2019-100799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2019] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To describe the incidence, type, aetiology and severity of injuries sustained by the International Ski Federation World Cup level female ski jumpers during the 2017-18 season. DESIGN Prospective cohort study. METHODS Sixty-seven female ski jump athletes from 16 countries were followed throughout the 17-week winter season. Preseason baseline demographic data and injury history were recorded via questionnaire. Prospective biweekly reports and retrospective end-of-season interviews provided data on all injuries requiring medical attention. RESULTS Seventeen injuries were recorded, corresponding to an incidence of 25.4 injuries/100 athletes/season. The incidence of time-loss and severe injuries were found to be 17.9 and 4.5, respectively. The knee was the most common site of injury (4/17; 23.5%). Fourteen injuries occurred on the ski jump hill and crash-landing was the most common mechanism of injury (10/14; 71%). Eighty-five per cent of all moderate and severe injuries occurred in snow or windy conditions. Length of jumps resulting in injury averaged 83.7% (95% CI 72.9% to 94.4%) of hill size. Moderate injuries causing 8-28 days absence from training activities were most common (7/17; 41%) and there were three severe injuries necessitating >4 weeks absence. CONCLUSION Injuries among elite female ski jumpers are common and the majority are acute, resulting in time loss from training and competition. The knee was the most common site of injury and poor weather conditions may be a risk factor. Future studies are needed to identify risk factors for injury and to guide injury prevention initiatives.
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Affiliation(s)
- Oleane Marthea Rebne Stenseth
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway .,Oslo Sports Trauma Research Center, The Norwegian School of Sports Sciences, Oslo, Norway
| | - Sindre Fløtlien Barli
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Oslo Sports Trauma Research Center, The Norwegian School of Sports Sciences, Oslo, Norway
| | - Richard Kyle Martin
- Department of Orthopedic Surgery and Sports Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Lars Engebretsen
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Oslo Sports Trauma Research Center, The Norwegian School of Sports Sciences, Oslo, Norway.,Orthopaedic Clinic, Oslo University Hospital and University of Oslo, Oslo, Norway
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Nardello F, Ferrari C, Spinelli L, Zamparo P. A kinematic analysis of water ski jumping in male and female elite athletes. Sports Biomech 2019; 20:985-1000. [PMID: 31223061 DOI: 10.1080/14763141.2019.1624813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of this study was to perform a kinematic analysis of the in-run, take-off and early flight phases in water ski jumping and to analyse the differences in linear/angular parameters between males and females. Forty-two elite skiers participated in this study (27 males; 15 females); their jumps were video recorded during competitions: the time course of absolute (trunk, thigh, ski) and relative (hip, knee, ankle) angles was calculated, as well as the (trochanter) resultant speed. Males were able to reach faster in-run speeds than females (25.4 ± 1.9 and 21.8 ± 1.2 m/s, respectively) and jumped further (56.2 ± 8.6 and 40.4 ± 6.3 m). Longer jumps were correlated with faster speeds in all phases (r range: 0.87-0.91, p < 0.001, n = 42). From take-off to early flight skiers extend their hip (86-109°) and knee (136-171°) angles, lean their trunk forward (49-41°) and raise their skis (20-51°); no major sex differences were observed in the body position (or ski incline) in these phases and none of the angular parameters was correlated with jump distance. Our results suggest that skiers should focus on achieving a larger in-run speed to maximise performance in this discipline.
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Affiliation(s)
- Francesca Nardello
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Chiara Ferrari
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Luca Spinelli
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Paola Zamparo
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Sklett VH, Lorås HW, Sigmundsson H. Self-Efficacy, Flow, Affect, Worry and Performance in Elite World Cup Ski Jumping. Front Psychol 2018; 9:1215. [PMID: 30065687 PMCID: PMC6057433 DOI: 10.3389/fpsyg.2018.01215] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/26/2018] [Indexed: 11/17/2022] Open
Abstract
The present study investigated the relationship between self-efficacy, flow, positive- and negative affect, worry and ski jumping performance, as well as the degree of influence these psychological factors have on ski jumping performance in specific competitions and overall World Cup ranking. World Cup ski jumpers (N = 40) responded to four questionnaires in the middle of the World Cup season, reporting their subjective experience during a competitive setting over a period of three consecutive days. Social Cognitive Theory (SCT) and Flow Theory was used as main conceptual frameworks. Self-efficacy was moderately related to ski jumping performance, both overall World Cup ranking (r = -0.37) and the results from the first out of three individual ski flying competitions (r = -0.36) and explained approximately 14% of the variance in the overall World Cup. Flow was moderately related to ski jumping performance, both overall World Cup ranking (Flow-Focus) (r = -0.34), and individual ski flying results from the first competition (Flow-Arousal) (r = -0.36). The Flow-Arousal explained approximately 13% of the variance in ski flying results. Worry was highly related to ski jumping performance in the second (r = 0.60) and third (r = 0.52) competition, indicating that approximately 36 and 27% of the variance in ski flying results could be accounted for by levels of worry, respectively. Negative affect was moderately related to ski flying performance (r = 0.34). These results show that psychological factors that regulate emotional states may be of importance for World Cup ski jumping performance, and that appropriate coping strategies, constructive mindset and motivation, appears to be essential in this regard. To our knowledge, this is the first study on the relationship between these psychological factors and ski jumping performance among World Cup athletes. The study adds important information about some of the dynamic features of emotional and psychological mechanisms involved during elite ski jumping performance.
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Affiliation(s)
- Vegard H. Sklett
- Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Håvard W. Lorås
- Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Hermundur Sigmundsson
- Department of Psychology, Faculty of Social and Educational Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Sport Science and Physical Education, Reykjavik University, Reykjavik, Iceland
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Abstract
The concept of kinematic chains has been systematically applied to biological systems since the 1950s. The course of a ski jump can be characterized as a change between closed and open kinematic chains. The purpose of this study was to determine a relationship between adjacent segments within the ski jumper’s body’s kinematic chain during the in-run phase of the ski jump. The in-run positions of 267 elite male ski jumpers who participated in the FIS World Cup events in Innsbruck, Austria, between 1992 and 2001 were analyzed (656 jumps). Two-dimensional (2-D) kinematic data were collected from the bodies of the subjects. Relationships between adjacent segments of the kinematic chain in the ski jumper’s body at the in-run position are greater nearer the chain’s ground contact. The coefficient of determination between the ankle and knee joint angles is 0.67. Changes in the segments’ positions in the kinematic chain of the ski jumper’s body are stable during longitudinal assessment. Changes in shank and thigh positions, in the sense of increase or decrease, are the same.
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Abstract
The purpose of our research was to establish the variability of correlation between the length of the jumps and selected multi-item kinematic variables (n=9) in the early flight phase technique of ski jumping. This study was conducted on a sample of elite Slovenian ski jumpers (N=29) who participated in the experiment on a jumping hill in Hinterzarten, Germany (HS95m) on the 20(th) of August, 2008. The highest and most significant correlations (p=0.01) with the length of the ski jump were found in the multi-item variable height of flying, which was also expressed with the highest level of stability of the explained total variance (TV) on the first factor (TV=69.13%). The most important characteristic of the aerodynamic aspect of early flight was the variable angle between the body chord and the horizontal axis with significantly high correlations (p<0.05). The stability of that aerodynamic factor was very high (TV=65.04%). The results were essentially similar for the multi-item variable angle between left leg and the horizontal axis (TV=61.88%). The rest of the multi-item kinematic variables did not have significant correlations with the multi-item variable length of jump. Only two more variables, the angle between the upper body and the horizontal plane (TV=53.69%), and the angle between left ski and left leg (TV=50.13%), had an explained common variance on the first factor greater than 50% of total variance. The results indicated that some kinematic parameters of ski jumping early flight technique were more important for success considering the length of the jump.
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Affiliation(s)
| | - Milan Čoh
- University of Ljubljana, Faculty of Sport, Slovenia
| | - Bojan Jošt
- University of Ljubljana, Faculty of Sport, Slovenia
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