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Spörri J, Beck L, Bonell Monsonís O, Alhammoud M, Bahr R, Bekker S, Collins D, Engebretsen L, Harvey J, Hörterer H, Mitterbauer G, Scherr J, Schobersberger W, Seiler J, Valtonen M, Waibel K, Weirather T, Gouttebarge V, Bolling C, Verhagen E. International Ski and Snowboard Federation consensus statement on warm-up and cool-down in competitive alpine and freestyle skiers and snowboarders. BMJ Open Sport Exerc Med 2025; 11:e002351. [PMID: 40226333 PMCID: PMC11987162 DOI: 10.1136/bmjsem-2024-002351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2024] [Accepted: 03/26/2025] [Indexed: 04/15/2025] Open
Abstract
In diverse sports, warm-up (WUP) and cool-down (CD) activities are highly effective at improving performance-relevant factors and reducing the risk of injury when applied systematically; however, scientific evidence is widely lacking in snow sports. Similarly, there is a lack of international harmonisation with current best practices; this especially applies to prevention efforts targeting younger athletes. This International Ski and Snowboard Federation (FIS) consensus statement aims to develop and promote recommendations regarding physical and psychological WUP&CD in competitive alpine and freestyle skiers and snowboarders. The selected panel members represented a group of experts diverse in terms of gender, expertise/background, level of competition and skiing and snowboarding discipline. They included researchers, officials, physicians, physiotherapists, coaches or former athletes with extensive experience in the subject area. However, there was a gender imbalance in the composition of the panel (7 women and 13 men) and certain freestyle disciplines (eg, aerials and moguls) were under-represented. Most importantly, there was a strong over-representation of European members (85%) on the consensus panel. For the consensus process, the RAND-UCLA Appropriateness Method was used. The panellists were asked to rate, discuss and rerate statements derived from the literature or expert/panellist opinions. The process was based on three online consensus sessions with different preparatory and follow-up tasks and three rounds of an online survey to vote on the statements. The final version of the FIS consensus statement was developed and approved after two iterative rounds of manuscript revision by the panel members. It is intended to guide athletes, coaches, medical staff of international and national federations and other entities who can promote and support appropriate WUP&CD practices for competitive alpine and freestyle skiers and snowboarders by providing support, resources or infrastructure.
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Affiliation(s)
- Jörg Spörri
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Lisa Beck
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Oriol Bonell Monsonís
- Amsterdam Collaboration on Health and Safety in Sports, IOC Research Centre for Prevention of Injury and Protection of Athlete Health, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands
| | - Marine Alhammoud
- Inter-University Laboratory of Human Movement Biology, Université Claude Bernard Lyon 1, Lyon, France
| | - Roald Bahr
- Oslo Sports Trauma Research Centre, Department of Sports Medicine, Norwegian School of Sports Sciences, Oslo, Norway
| | - Sheree Bekker
- Centre for Health and Injury and Illness Prevention in Sport and the UK Collaborating Centre on Injury and Illness Prevention in Sport, Department for Health, University of Bath, Bath, UK
| | - Dave Collins
- Human Performance Science Research Group, Institute for Sport, Physical Education and Health Sciences, The University of Edinburgh, Edinburgh, UK
| | - Lars Engebretsen
- Medical and Scientific Department, International Olympic Committee, Lausanne, Switzerland
| | | | - Hubert Hörterer
- Medical Committee, International Ski and Snowboard Federation, Oberhofen, Switzerland
| | - Gerald Mitterbauer
- FIS Athlete Health Unit, International Ski and Snowboard Federation, Oberhofen, Switzerland
| | - Johannes Scherr
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Wolfgang Schobersberger
- Medical Committee, International Ski and Snowboard Federation, Oberhofen, Switzerland
- Institute for Sport Medicine, Alpine Medicine and Health Tourism (ISAG), UMIT TIROL Private University for Health Sciences and Technology GmbH, Hall and University Hospital, Innsbruck, Austria
| | - Jan Seiler
- Department for Elite Sport, Swiss Federal Institute of Sport Magglingen (SFISM), Magglingen, Switzerland
| | - Maarit Valtonen
- Medical Committee, International Ski and Snowboard Federation, Oberhofen, Switzerland
- Finnish Institute of High-Performance Sport KIHU, Jyväskylä, Finland
| | | | - Tina Weirather
- FIS Athlete Health Unit, International Ski and Snowboard Federation, Oberhofen, Switzerland
| | - Vincent Gouttebarge
- Amsterdam UMC location University of Amsterdam, Department of Orthopedic Surgery and Sports Medicine, Amsterdam, The Netherlands
- Section Sports Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Caroline Bolling
- Amsterdam Collaboration on Health and Safety in Sports, IOC Research Centre for Prevention of Injury and Protection of Athlete Health, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands
- Amsterdam UMC location University of Amsterdam, Department of Orthopedic Surgery and Sports Medicine, Amsterdam, The Netherlands
| | - Evert Verhagen
- Amsterdam Collaboration on Health and Safety in Sports, IOC Research Centre for Prevention of Injury and Protection of Athlete Health, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands
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Bonell Monsonís O, Spörri J, Warsen M, Bolling C, Gouttebarge V, Verhagen E. We know a lot about little and little about a lot: A contextualized scoping review on injury prevention in alpine ski racing. Scand J Med Sci Sports 2024; 34:e14533. [PMID: 37955281 DOI: 10.1111/sms.14533] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/19/2023] [Accepted: 10/25/2023] [Indexed: 11/14/2023]
Abstract
BACKGROUND Our goal was to summarize and contextualize the available literature on alpine ski racing injury epidemiology, injury etiology, injury prevention measures, injury prevention context, and implementation issues. MATERIALS AND METHODS We searched four electronic databases using predetermined search terms. We included original studies that assessed injury, injury risk factors, and injury mechanisms, and assessed and reported the effect of an injury prevention measure in alpine ski racing. Two authors independently conducted title-abstract screening, and one performed the full-text review. For data synthesis and categorization, we used the Translating Research into the Injury Prevention Practice framework and a modified and adapted version of the Haddon matrix. RESULTS Of the 157 included studies, most corresponded to injury epidemiology and etiology, whereas few studies encompassed injury prevention measure development, implementation and evaluation. Preventive interventions targeting equipment, rules and regulations, course design and snow preparation were the most prevalent in the literature. Furthermore, various contextual factors in the current literature have been found, including gender, competition level, countries and federations, and time periods within a season. CONCLUSIONS We provided an in-depth and comprehensive overview of the current state-of-the-art in the alpine ski racing context. We know a lot about little and little about a lot across all the areas associated with injury prevention in such context. The limitations in the literature yield a road map for designing future injury prevention studies to address the key gaps identified. A more comprehensive context-driven approach throughout all stages of injury prevention would benefit the ultimate implementation of effective preventive strategies.
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Affiliation(s)
- Oriol Bonell Monsonís
- Amsterdam Collaboration on Health and Safety in Sports, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC, University Medical Centers - Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Musculoskeletal Health and Sports, Amsterdam, The Netherlands
| | - Jörg Spörri
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Marit Warsen
- Amsterdam Collaboration on Health and Safety in Sports, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC, University Medical Centers - Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Caroline Bolling
- Amsterdam Collaboration on Health and Safety in Sports, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC, University Medical Centers - Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam UMC Location University of Amsterdam, Orthopedic Surgery and Sports Medicine, Amsterdam, The Netherlands
| | - Vincent Gouttebarge
- Amsterdam Movement Sciences, Musculoskeletal Health and Sports, Amsterdam, The Netherlands
- Amsterdam UMC Location University of Amsterdam, Orthopedic Surgery and Sports Medicine, Amsterdam, The Netherlands
- Section Sports Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Evert Verhagen
- Amsterdam Collaboration on Health and Safety in Sports, Department of Public and Occupational Health, Amsterdam Movement Sciences, Amsterdam UMC, University Medical Centers - Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Amsterdam Movement Sciences, Musculoskeletal Health and Sports, Amsterdam, The Netherlands
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Heinrich D, van den Bogert AJ, Mössner M, Nachbauer W. Model-based estimation of muscle and ACL forces during turning maneuvers in alpine skiing. Sci Rep 2023; 13:9026. [PMID: 37270655 DOI: 10.1038/s41598-023-35775-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/23/2023] [Indexed: 06/05/2023] Open
Abstract
In alpine skiing, estimation of the muscle forces and joint loads such as the forces in the ACL of the knee are essential to quantify the loading pattern of the skier during turning maneuvers. Since direct measurement of these forces is generally not feasible, non-invasive methods based on musculoskeletal modeling should be considered. In alpine skiing, however, muscle forces and ACL forces have not been analyzed during turning maneuvers due to the lack of three dimensional musculoskeletal models. In the present study, a three dimensional musculoskeletal skier model was successfully applied to track experimental data of a professional skier. During the turning maneuver, the primary activated muscles groups of the outside leg, bearing the highest loads, were the gluteus maximus, vastus lateralis as well as the medial and lateral hamstrings. The main function of these muscles was to generate the required hip extension and knee extension moments. The gluteus maximus was also the main contributor to the hip abduction moment when the hip was highly flexed. Furthermore, the lateral hamstrings and gluteus maximus contributed to the hip external rotation moment in addition to the quadratus femoris. Peak ACL forces reached 211 N on the outside leg with the main contribution in the frontal plane due to an external knee abduction moment. Sagittal plane contributions were low due to consistently high knee flexion (> 60[Formula: see text]), substantial co-activation of the hamstrings and the ground reaction force pushing the anteriorly inclined tibia backwards with respect to the femur. In conclusion, the present musculoskeletal simulation model provides a detailed insight into the loading of a skier during turning maneuvers that might be used to analyze appropriate training loads or injury risk factors such as the speed or turn radius of the skier, changes of the equipment or neuromuscular control parameters.
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Affiliation(s)
- Dieter Heinrich
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria.
| | | | - Martin Mössner
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Werner Nachbauer
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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Nitschke M, Marzilger R, Leyendecker S, Eskofier BM, Koelewijn AD. Change the direction: 3D optimal control simulation by directly tracking marker and ground reaction force data. PeerJ 2023; 11:e14852. [PMID: 36778146 PMCID: PMC9912948 DOI: 10.7717/peerj.14852] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 01/13/2023] [Indexed: 02/10/2023] Open
Abstract
Optimal control simulations of musculoskeletal models can be used to reconstruct motions measured with optical motion capture to estimate joint and muscle kinematics and kinetics. These simulations are mutually and dynamically consistent, in contrast to traditional inverse methods. Commonly, optimal control simulations are generated by tracking generalized coordinates in combination with ground reaction forces. The generalized coordinates are estimated from marker positions using, for example, inverse kinematics. Hence, inaccuracies in the estimated coordinates are tracked in the simulation. We developed an approach to reconstruct arbitrary motions, such as change of direction motions, using optimal control simulations of 3D full-body musculoskeletal models by directly tracking marker and ground reaction force data. For evaluation, we recorded three trials each of straight running, curved running, and a v-cut for 10 participants. We reconstructed the recordings with marker tracking simulations, coordinate tracking simulations, and inverse kinematics and dynamics. First, we analyzed the convergence of the simulations and found that the wall time increased three to four times when using marker tracking compared to coordinate tracking. Then, we compared the marker trajectories, ground reaction forces, pelvis translations, joint angles, and joint moments between the three reconstruction methods. Root mean squared deviations between measured and estimated marker positions were smallest for inverse kinematics (e.g., 7.6 ± 5.1 mm for v-cut). However, measurement noise and soft tissue artifacts are likely also tracked in inverse kinematics, meaning that this approach does not reflect a gold standard. Marker tracking simulations resulted in slightly higher root mean squared marker deviations (e.g., 9.5 ± 6.2 mm for v-cut) than inverse kinematics. In contrast, coordinate tracking resulted in deviations that were nearly twice as high (e.g., 16.8 ± 10.5 mm for v-cut). Joint angles from coordinate tracking followed the estimated joint angles from inverse kinematics more closely than marker tracking (e.g., root mean squared deviation of 1.4 ± 1.8 deg vs. 3.5 ± 4.0 deg for v-cut). However, we did not have a gold standard measurement of the joint angles, so it is unknown if this larger deviation means the solution is less accurate. In conclusion, we showed that optimal control simulations of change of direction running motions can be created by tracking marker and ground reaction force data. Marker tracking considerably improved marker accuracy compared to coordinate tracking. Therefore, we recommend reconstructing movements by directly tracking marker data in the optimal control simulation when precise marker tracking is required.
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Affiliation(s)
- Marlies Nitschke
- Machine Learning and Data Analytics Lab, Department of Artificial Intelligence in Biomedical Engineering (AIBE), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Robert Marzilger
- Division Positioning and Networks, Fraunhofer IIS, Fraunhofer Institute for Integrated Circuits IIS, Nuremberg, Germany
| | - Sigrid Leyendecker
- Institute of Applied Dynamics, Department of Mechanical Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bjoern M. Eskofier
- Machine Learning and Data Analytics Lab, Department of Artificial Intelligence in Biomedical Engineering (AIBE), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Anne D. Koelewijn
- Machine Learning and Data Analytics Lab, Department of Artificial Intelligence in Biomedical Engineering (AIBE), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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A biomechanical analysis of skiing-related anterior cruciate ligament injuries based on biomedical imaging technology. Med Eng Phys 2022; 110:103907. [PMID: 36307365 DOI: 10.1016/j.medengphy.2022.103907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022]
Abstract
Alpine skiing is an attractive but highly risky sport, and the anterior cruciate ligament (ACL) tear is one of the most common diagnoses of skiing-related injuries. To better prevent such injuries among athletes and recreational skiers, we developed a facile and reliable biomechanical method to analyze the differences between "right" and "wrong" movements during skiing and their impacts on ACL stress loading. Unlike those conventional methods that are very difficult to implement and time-consuming, our method was developed based on inverse dynamics analyses and video capture, which were much easier to implement in the real-world setting. It is shown that, with a harmful skiing action, the knee joint's maximum reaction force significantly increases compared to nonharmful skiing actions. The peak front-and-rear force increased from 1242 N to 3105 N, and the peak axial force increased from 1023 N to 3443 N, which significantly exceeded the maximum tensile loading (2000 N) in the ACL. Our results are proven to be reliable and consistent with findings obtained with other methods. This method may substitute current complex analytical methods and be easier to apply in sports-related injury-prevention applications.
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Heinrich D, Van den Bogert AJ, Nachbauer W. Estimation of Joint Moments During Turning Maneuvers in Alpine Skiing Using a Three Dimensional Musculoskeletal Skier Model and a Forward Dynamics Optimization Framework. Front Bioeng Biotechnol 2022; 10:894568. [PMID: 35814020 PMCID: PMC9269104 DOI: 10.3389/fbioe.2022.894568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 06/02/2022] [Indexed: 11/13/2022] Open
Abstract
In alpine skiing, estimation of the joint moments acting onto the skier is essential to quantify the loading of the skier during turning maneuvers. In the present study, a novel forward dynamics optimization framework is presented to estimate the joint moments acting onto the skier incorporating a three dimensional musculoskeletal model (53 kinematic degrees of freedom, 94 muscles). Kinematic data of a professional skier performing a turning maneuver were captured and used as input data to the optimization framework. In the optimization framework, the musculoskeletal model of the skier was applied to track the experimental data of a skier and to estimate the underlying joint moments of the skier at the hip, knee and ankle joints of the outside and inside leg as well as the lumbar joint. During the turning maneuver the speed of the skier was about 14 m/s with a minimum turn radius of about 16 m. The highest joint moments were observed at the lumbar joint with a maximum of 1.88 Nm/kg for lumbar extension. At the outside leg, the highest joint moments corresponded to the hip extension moment with 1.27 Nm/kg, the knee extension moment with 1.02 Nm/kg and the ankle plantarflexion moment with 0.85 Nm/kg. Compared to the classical inverse dynamics analysis, the present framework has four major advantages. First, using a forward dynamic optimization framework the underlying kinematics of the skier as well as the corresponding ground reaction forces are dynamically consistent. Second, the present framework can cope with incomplete data (i.e., without ground reaction force data). Third, the computation of the joint moments is less sensitive to errors in the measurement data. Fourth, the computed joint moments are constrained to stay within the physiological limits defined by the musculoskeletal model.
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Affiliation(s)
- Dieter Heinrich
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
- *Correspondence: Dieter Heinrich,
| | | | - Werner Nachbauer
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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Waltz RA, Comfort SM, Pierpoint LA, Briggs KK, Philippon MJ. Femoroacetabular Impingement in Elite Skiers and Snowboarders: Return to Sports and Outcomes After Hip Arthroscopy. Am J Sports Med 2022; 50:1564-1570. [PMID: 35384744 DOI: 10.1177/03635465221085663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Hip arthroscopy has been shown to be an effective treatment for femoroacetabular impingement (FAI) in high-level athletes; however, limited outcome and return-to-play data exist for hip arthroscopy in skiers and snowboarders. PURPOSES To determine the return-to-sports rate of elite skiers and snowboarders who have undergone hip arthroscopic surgery for FAI and to assess hip-related outcomes at a minimum 2-year follow-up. STUDY DESIGN Case series; Level of evidence, 4. METHODS Elite skiers and snowboarders who underwent hip arthroscopy for the treatment of FAI between 2005 and 2018 were identified via a retrospective review of prospectively collected data. Data were obtained from fis-ski.org, usskiandsnowboard.org, xgames.com, and wikipedia.org, including information on each player's career length, participation on a national team, and time between surgery and first competition after surgery. Patient-reported outcomes (PROs) were prospectively collected preoperatively and at minimum 2 years postoperatively. RESULTS In total, 26 elite skiers and snowboarders (34 hips) were included. The mean ± standard deviation age at surgery was 24.5 ± 6.7 years (range, 18.7-46.8 years). A total of 85% (22/26) returned to elite-level competition at 8.9 months (range, 2.9-23.7 months) with an average career length of 3.6 ± 2.7 years after surgery. Four athletes (5 hips) required revision arthroscopy, with adhesions being the most frequent indication. At a mean follow-up of 7.7 ± 3.2 years, significant improvement in PROs (P < .05) was demonstrated for the Hip Outcome Score (HOS)-Activities of Daily Living (from 76 ± 20 to 95 ± 6), HOS-Sport Specific Subscale (from 63 ± 28 to 92 ± 14), modified Harris Hip Score (from 70 ± 19 to 89 ± 12), and 12-Item Short Form Health Survey Physical Component Summary (from 45 ± 11 to 54 ± 8). Patient satisfaction had a mean of 8 ± 2 (range, 1-10) and median of 10. CONCLUSION The return-to-competition rate in elite skiers and snowboarders after hip arthroscopy for FAI was 85% at an average of 8.9 months and with a career length of 3.6 years after surgery. Significant improvement in PROs was demonstrated for the HOS-Activities of Daily Living, HOS-Sport Specific Subscale, modified Harris Hip Score, and 12-Item Short Form Health Survey Physical Component Summary, with a median patient satisfaction score of 10. These findings support hip arthroscopy as an effective procedure for the treatment of FAI in elite skiers and snowboarders with symptomatic activity-limiting hip pain, allowing them to return to their previous levels of competition at a high rate.
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Affiliation(s)
- Robert A Waltz
- Steadman Philippon Research Institute, Vail, Colorado, USA.,The Steadman Clinic and US Coalition for the Prevention of Illness and Injury in Sport, Vail, Colorado, USA.,Navy Medical Readiness and Training Unit, United States Naval Academy, Annapolis, Maryland, USA
| | | | | | - Karen K Briggs
- Steadman Philippon Research Institute, Vail, Colorado, USA
| | - Marc J Philippon
- Steadman Philippon Research Institute, Vail, Colorado, USA.,The Steadman Clinic and US Coalition for the Prevention of Illness and Injury in Sport, Vail, Colorado, USA
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Kiers K, Ellenberger L, Jermann J, Oberle F, Frey WO, Spörri J. Prospective Study on Dynamic Postural Stability in Youth Competitive Alpine Skiers: Test-Retest Reliability and Reference Values as a Function of Sex, Age and Biological Maturation. Front Physiol 2022; 13:804165. [PMID: 35480039 PMCID: PMC9035548 DOI: 10.3389/fphys.2022.804165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 03/28/2022] [Indexed: 11/23/2022] Open
Abstract
This study aimed 1) to assess the test-retest reliability of dynamic postural stability index (DPSI) assessments using a ski-specific jump protocol that consists of single-leg landings on a three-dimensional force plate after forward-performed double-leg drop jumps from a box over a hurdle (DJSLLs), 2) to provide reference values for female and male youth competitive alpine skiers; 3) to explore their changes in DPSI over 3 years during adolescence; and 4) to investigate potential associations of DPSI with age and biological maturation. Using three-dimensional force plates, 16 healthy subjects were tested on the same day (test-retest reliability experiment; five test-retest assessments of right leg landings), and 76 youth skiers aged 13–15 years were tested 3 times within 2 years (main experiment; average of two trials per leg each time). The test-retest reliability experiment revealed an ICC(3,1) and 95% CI of 0.86 [0.74, 0.94] for absolute DPSI assessment. The within-subject SEM of absolute DPSI was 16.30 N [13.66 N, 20.65 N], and the standardized typical error was moderate (0.39 [0.33, 0.50]). Both absolute and relative DPSI values were comparable between male and female youth competitive alpine skiers. The mean absolute DPSI in year 1 (195.7 ± 40.9 N), year 2 (196.5 ± 38.9 N) and year 3 (211.5 ± 41.3 N) continuously increased (i.e., worsened) (p < 0.001). Mean relative, i.e. body weight force normalized, DPSI values significantly decreased, i.e., improved, from year 1 to 2 (0.42 ± 0.01 vs. 0.36 ± 0.004; p < 0.001) and year 1 to 3 (0.42 ± 0.01 vs. 0.36 ± 0.01; p < 0.001). Absolute DPSI correlated with age and biological maturation, while no such correlations were found for relative DPSI values. Our findings suggest that DPSI is a reliable and sensitive measure of dynamic postural control during DJSLLs and that relative DPSI improves annually in competitive youth skiers when accounting for body weight. Future work should consider biological maturation testing during the growth spurt, and normalizing to body weight force could be a possible solution.
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Affiliation(s)
- Kirsten Kiers
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Lynn Ellenberger
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Julia Jermann
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Felix Oberle
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Walter O. Frey
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Jörg Spörri
- Sports Medical Research Group, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- University Centre for Prevention and Sports Medicine, Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- *Correspondence: Jörg Spörri,
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Heinrich D, van den Bogert AJ, Nachbauer W. Predicting neuromuscular control patterns that minimize ACL forces during injury prone jump landing maneuvers in downhill skiing using a musculoskeletal simulation model. Eur J Sport Sci 2022; 23:703-713. [PMID: 35400304 DOI: 10.1080/17461391.2022.2064770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Competitive skiers encounter a high risk of sustaining an ACL injury during jump-landing in downhill ski racing. Facing an injury-prone landing manoeuvre, there is a lack of knowledge regarding optimum control strategies. So, the purpose of the present study was to investigate possible neuromuscular control patterns to avoid injury during injury-prone jump-landing manoeuvres. A computational approach was used to generate a series of 190 injury-prone jump-landing manoeuvres based on a 25-degree-of-freedom sagittal plane musculoskeletal skier model. Using a dynamic optimization framework, each injury-prone landing manoeuvre was resolved to identify muscle activation patterns of the lower limbs and corresponding kinematic changes that reduce peak ACL force. In the 190 injury-prone jump-landing simulations, ACL forces peaked during the first 50 ms after ground contact. Optimized muscle activation patterns, that reduced peak ACL forces, showed increased activation of the monoarticular hip flexors, ankle dorsi- and plantar flexors as well as hamstrings prior to or during the early impact phase (<50 ms). The corresponding kinematic changes were characterized by increased hip and knee flexion and less backward lean of the skier at initial ground contact and the following impact phase. Injury prevention strategies should focus on increased activation of the monoarticular hip flexors, ankle plantar flexors and rapid and increased activation of the hamstrings in combination with a flexed landing position and decreased backward lean to reduce ACL injury risk during the early impact phase (<50 ms) of jump landing.HighlightsFirst study investigating advantageous control strategies during injury-prone jump-landing manoeuvres in downhill skiing using a musculoskeletal simulation model and dynamic optimization framework.The simulation results predicted high injury risk during the first 50 ms after initial ground contact.Optimized neuromuscular control patterns showed adapted activation patterns (timing and amplitude) of muscles crossing the knee as well as the hip and ankle joints prior to and after initial ground contact, respectively.An optimized control strategy during an injury-prone landing manoeuvre was characterized kinematically by increasing hip and knee flexion and less backward lean of the skier at initial ground contact and the following impact phase.
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Affiliation(s)
- Dieter Heinrich
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria
| | | | - Werner Nachbauer
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria
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Heinrich D, van den Bogert AJ, Csapo R, Nachbauer W. A model-based approach to predict neuromuscular control patterns that minimize ACL forces during jump landing. Comput Methods Biomech Biomed Engin 2020; 24:612-622. [PMID: 33185129 DOI: 10.1080/10255842.2020.1842376] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Jump landing is a common situation leading to knee injuries involving the anterior cruciate ligament (ACL) in sports. Although neuromuscular control is considered as a key injury risk factor, there is a lack of knowledge regarding optimum control strategies that reduce ACL forces during jump landing. In the present study, a musculoskeletal model-based computational approach is presented that allows identifying neuromuscular control patterns that minimize ACL forces during jump landing. The approach is demonstrated for a jump landing maneuver in downhill skiing, which is one out of three main injury mechanisms in competitive skiing.
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Affiliation(s)
- Dieter Heinrich
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | | | - Robert Csapo
- Department of Orthopedic Sports Medicine and Injury Prevention, University for Health Sciences, Medical Informatics and Technology, Hall, Austria
| | - Werner Nachbauer
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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11
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Platzer HP, Barth M, Giger A, Schröcksnadel P, Nachbauer W. Did injury incidence in alpine ski racing change after equipment regulations? An evaluation based on the injury surveillance system of the Austrian Ski Federation. J Sci Med Sport 2020; 24:1044-1048. [PMID: 32807655 DOI: 10.1016/j.jsams.2020.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 06/25/2020] [Accepted: 07/13/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To assess the effects of alpine competition equipment regulations from 2003, 2007 and 2012 on severe injury incidence. DESIGN Case study METHOD: Data originated from records of the injury surveillance system of the Austrian Ski Federation. Injuries from the seasons 2001-2017 were divided in four periods between the equipment regulations. For comparison of consecutive periods, risk ratios (RR = later period / preceding period) with 95% CI were calculated. Total severe injury events, events with severe knee injuries, and events with severe ACL injuries were separately investigated. RESULTS A significant increase of total severe injury incidence was found after the equipment regulation in 2003 (RR1.52, 95% CI 1.00-2.31). None of the other comparisons revealed significance (p<0.05) or statistical trends (p<0.1). Only the minority (40%) of the RR showed a reduction in the injury incidence of the Austrian Ski Team (lowest RR 0.78). 60% of the RR increased after the regulations (highest RR 1.63). CONCLUSIONS Even though statistical uncertainties remain, our findings allow the conclusion, that the implemented equipment regulations did not cause a noticeable reduction of injuries. The three analysed equipment regulations were not appropriate or were counteracted by other factors.
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Affiliation(s)
- Hans-Peter Platzer
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020 Innsbruck, Austria; Research Center Snow, Ski, and Alpine Sport, Fürstenweg 185, 6020 Innsbruck, Austria.
| | - Michael Barth
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020 Innsbruck, Austria
| | - Anton Giger
- Austrian Ski Federation, Olympiastraße 10, 6020 Innsbruck, Austria
| | | | - Werner Nachbauer
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020 Innsbruck, Austria; Research Center Snow, Ski, and Alpine Sport, Fürstenweg 185, 6020 Innsbruck, Austria
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12
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Dorschky E, Nitschke M, Martindale CF, van den Bogert AJ, Koelewijn AD, Eskofier BM. CNN-Based Estimation of Sagittal Plane Walking and Running Biomechanics From Measured and Simulated Inertial Sensor Data. Front Bioeng Biotechnol 2020; 8:604. [PMID: 32671032 PMCID: PMC7333079 DOI: 10.3389/fbioe.2020.00604] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022] Open
Abstract
Machine learning is a promising approach to evaluate human movement based on wearable sensor data. A representative dataset for training data-driven models is crucial to ensure that the model generalizes well to unseen data. However, the acquisition of sufficient data is time-consuming and often infeasible. We present a method to create realistic inertial sensor data with corresponding biomechanical variables by 2D walking and running simulations. We augmented a measured inertial sensor dataset with simulated data for the training of convolutional neural networks to estimate sagittal plane joint angles, joint moments, and ground reaction forces (GRFs) of walking and running. When adding simulated data, the root mean square error (RMSE) of the test set of hip, knee, and ankle joint angles decreased up to 17%, 27% and 23%, the RMSE of knee and ankle joint moments up to 6% and the RMSE of anterior-posterior and vertical GRF up to 2 and 6%. Simulation-aided estimation of joint moments and GRFs was limited by inaccuracies of the biomechanical model. Improving the physics-based model and domain adaptation learning may further increase the benefit of simulated data. Future work can exploit biomechanical simulations to connect different data sources in order to create representative datasets of human movement. In conclusion, machine learning can benefit from available domain knowledge on biomechanical simulations to supplement cumbersome data collections.
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Affiliation(s)
- Eva Dorschky
- Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Marlies Nitschke
- Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christine F. Martindale
- Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Anne D. Koelewijn
- Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bjoern M. Eskofier
- Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
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Aminoff AS, Agnvall C, Todd C, Jónasson P, Thoreson O, Sansone M, Swärd L, Karlsson J, Baranto A. Young elite Alpine and Mogul skiers have a higher prevalence of cam morphology than non-athletes. Knee Surg Sports Traumatol Arthrosc 2020; 28:1262-1269. [PMID: 30367199 PMCID: PMC7148273 DOI: 10.1007/s00167-018-5236-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 10/17/2018] [Indexed: 11/29/2022]
Abstract
PURPOSE To investigate the prevalence of cam morphology in (1) a group of young elite Mogul and Alpine skiers compared with non-athletes and (2) between the sexes. METHOD The hip joints of 87 subjects [n = 61 young elite skiers (29 females and 32 males) and n = 26 non-athletes (17 females and 9 males)] were examined using MRI, for measurements of the presence of cam morphology (α-angle ≥ 55). RESULTS The skiers had a significantly higher prevalence of cam morphology compared with the non-athletes (49% vs 19%, p = 0.009). A significant difference (p < 0.001) was also found between females and males, where 22% of the females and 61% of the males had cam morphology. Among the skiers, there was also a significant difference (p < 0.001) between the sexes, where 28% of the females and 68% of the males had cam morphology. This difference between the sexes was not found in the non-athletic group. No significant differences were found between Mogul and Alpine skiers. CONCLUSION Young male elite skiers have a higher prevalence of cam morphology of the hips compared with non-athletes. LEVEL OF EVIDENCE II.
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Affiliation(s)
- Anna Swärd Aminoff
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden. .,Åre Hälsocentral, Box 25, 830 14, Åre, Sweden.
| | | | - Carl Todd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | | | - Olof Thoreson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Mikael Sansone
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Leif Swärd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jon Karlsson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Adad Baranto
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden
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Dorschky E, Nitschke M, Seifer AK, van den Bogert AJ, Eskofier BM. Estimation of gait kinematics and kinetics from inertial sensor data using optimal control of musculoskeletal models. J Biomech 2019; 95:109278. [DOI: 10.1016/j.jbiomech.2019.07.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 07/16/2019] [Accepted: 07/18/2019] [Indexed: 11/24/2022]
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Bessone V, Petrat J, Schwirtz A. Ground Reaction Forces and Kinematics of Ski Jump Landing Using Wearable Sensors. SENSORS (BASEL, SWITZERLAND) 2019; 19:E2011. [PMID: 31035683 PMCID: PMC6539877 DOI: 10.3390/s19092011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/15/2019] [Accepted: 04/27/2019] [Indexed: 01/04/2023]
Abstract
In the past, technological issues limited research focused on ski jump landing. Today, thanks to the development of wearable sensors, it is possible to analyze the biomechanics of athletes without interfering with their movements. The aims of this study were twofold. Firstly, the quantification of the kinetic magnitude during landing is performed using wireless force insoles while 22 athletes jumped during summer training on the hill. In the second part, the insoles were combined with inertial motion units (IMUs) to determine the possible correlation between kinematics and kinetics during landing. The maximal normal ground reaction force (GRFmax) ranged between 1.1 and 5.3 body weight per foot independently when landing using the telemark or parallel leg technique. The GRFmax and impulse were correlated with flying time (p < 0.001). The hip flexions/extensions and the knee and hip rotations of the telemark front leg correlated with GRFmax (r = 0.689, p = 0.040; r = -0.670, p = 0.048; r = 0.820, p = 0.007; respectively). The force insoles and their combination with IMUs resulted in promising setups to analyze landing biomechanics and to provide in-field feedback to the athletes, being quick to place and light, without limiting movement.
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Affiliation(s)
- Veronica Bessone
- Department of Biomechanics in Sports, Faculty of Sport and Health Sciences, Technical University of Munich, 80992 Munich, Germany.
| | - Johannes Petrat
- Department of Biomechanics in Sports, Faculty of Sport and Health Sciences, Technical University of Munich, 80992 Munich, Germany.
- Olympic Training Center of Bavaria, 80809 Munich, Germany.
| | - Ansgar Schwirtz
- Department of Biomechanics in Sports, Faculty of Sport and Health Sciences, Technical University of Munich, 80992 Munich, Germany.
- Olympic Training Center of Bavaria, 80809 Munich, Germany.
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16
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Eberle R, Heinrich D, van den Bogert AJ, Oberguggenberger M, Nachbauer W. An approach to generate noncontact ACL-injury prone situations on a computer using kinematic data of non-injury situations and Monte Carlo simulation. Comput Methods Biomech Biomed Engin 2018; 22:3-10. [DOI: 10.1080/10255842.2018.1522534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- R. Eberle
- Unit for Engineering Mathematics, Department of Engineering Science, University of Innsbruck, Innsbruck, Austria
| | - D. Heinrich
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - A. J. van den Bogert
- Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, USA
| | - M. Oberguggenberger
- Unit for Engineering Mathematics, Department of Engineering Science, University of Innsbruck, Innsbruck, Austria
| | - W. Nachbauer
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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Swärd Aminoff A, Agnvall C, Todd C, Jónasson P, Sansone M, Thoreson O, Swärd L, Karlsson J, Baranto A. The effect of pelvic tilt and cam on hip range of motion in young elite skiers and nonathletes. Open Access J Sports Med 2018; 9:147-156. [PMID: 30123011 PMCID: PMC6084081 DOI: 10.2147/oajsm.s162675] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background Current knowledge of the effect of changes in posture and the way cam morphology of the hip joint may affect hip range of motion (ROM) is limited. Purpose To determine the effect of changes in pelvic tilt (PT) on hip ROM and with/without the presence of cam. Study design This was a cross-sectional study. Materials and methods The hip ROM of 87 subjects (n=61 young elite skiers, n=26 nonathletes) was examined using a goniometer, in three different seated postures (flexed, neutral, and extended). The hips of the subjects were further subgrouped into cam and no-cam morphology, based on the magnetic resonance imaging findings in the hips. Results There was a significant correlation between the hip ROM and the seated posture in both extended and flexed postures compared with the neutral posture. There was a significant decrease in internal hip rotation when the subjects sat with an extended posture with maximum anterior PT (p<0.0001). There was a significant increase in internal hip rotation when the subjects sat with a flexed posture with maximum posterior PT (p<0.001). External rotation was significantly decreased in an extended posture with maximum anterior PT (p<0.0001), but there was no difference in flexed posture with maximum posterior PT. The hips with cam morphology had reduced internal hip rotation in all three positions, but they responded to the changes in position in a similar manner to hips without cam morphology. Conclusion Dynamic changes in PT significantly influence hip ROM in young people, independent of cam or no-cam morphology.
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Affiliation(s)
- Anna Swärd Aminoff
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | - Cecilia Agnvall
- Sports Medicine Åre, Åre, Sweden.,Åre Ski Academy, Åre, Sweden
| | - Carl Todd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | | | - Mikael Sansone
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | - Olof Thoreson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | - Leif Swärd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | - Jon Karlsson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
| | - Adad Baranto
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, and Sahlgrenska University Hospital, Gothenburg, Sweden,
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18
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Todd C, Aminoff AS, Agnvall C, Thoreson O, Swärd L, Karlsson J, Baranto A. No difference in prevalence of spine and hip pain in young Elite skiers. Knee Surg Sports Traumatol Arthrosc 2018; 26:1959-1965. [PMID: 29204863 PMCID: PMC6061433 DOI: 10.1007/s00167-017-4733-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/25/2017] [Indexed: 02/07/2023]
Abstract
PURPOSE To investigate the prevalence between back and hip pain in young Elite skiers. METHODS Sample group (n = 102), consisted of young Elite skiers (n = 75) and age-matched non-athletes (n = 27), all completed a three-part back and hip pain questionnaire, Oswestry Disability Index and EuroQoL to evaluate general health, activity level, back and hip pain prevalence. RESULTS No significant differences were shown for lifetime prevalence of back pain in the skiers (50%) compared with controls (44%) (n.s.). Duration of back pain for the skiers showed (30%) > 1 year, whilst (46%) > 5 years. A significant difference was shown with increased Visual Analogue Scale back pain levels for skiers 5.3 (SD 3.1) compared with controls 2.4 (SD 1.9, p = 0.025). No significant differences were shown for lifetime prevalence of hip pain in skiers (21%) compared with controls (8%) (n.s.). CONCLUSION Young Elite skiers are shown not to have increased lifetime prevalence for back and hip pain compared with a non-athletic control group. LEVEL OF EVIDENCE II.
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Affiliation(s)
- Carl Todd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden.
- The Carl Todd Clinic, 5 Pickwick Park, Park Lane, Corsham, SN13 0HN, UK.
| | - Anna Swärd Aminoff
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden
| | - Cecilia Agnvall
- Sportsmedicine Åre and Åre Ski High School, Göthenburg, Sweden
| | - Olof Thoreson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden
| | - Leif Swärd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden
| | - Jon Karlsson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden
| | - Adad Baranto
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Göthenburg, Sweden
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Heinrich D, van den Bogert AJ, Nachbauer W. Peak ACL force during jump landing in downhill skiing is less sensitive to landing height than landing position. Br J Sports Med 2018; 52:1086-1090. [DOI: 10.1136/bjsports-2017-098964] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2018] [Indexed: 11/03/2022]
Abstract
BackgroundCompetitive skiers face a high risk of sustaining an ACL injury during jump landing in downhill skiing. There is a lack of knowledge on how landing height affects this risk.ObjectivesTo evaluate the effect of varied landing height on peak ACL force during jump landing and to compare the effect of the landing height with the effect of the landing position varied by the trunk lean of the skier.MethodsA 25-degree-of-freedom sagittal plane musculoskeletal model of an alpine skier, accompanied by a dynamic optimisation framework, was used to simulate jump landing manoeuvres in downhill skiing. First, a reference simulation was computed tracking experimental data of competitive downhill skier performing a jump landing manoeuvre. Second, sensitivity studies were performed computing 441 landing manoeuvres with perturbed landing height and trunk lean of the skier, and the corresponding effects on peak ACL force were determined.ResultsThe sensitivity studies revealed that peak ACL force increased with jump height and backward lean of the skier as expected. However, peak ACL was about eight times more sensitive to the trunk lean of the skier compared with landing height. The decreased sensitivity of the landing height was based on the lower effects on the knee muscle forces and the shear component of the knee joint reaction force.ConclusionPreventive measures are suggested to focus primarily on avoiding trunk backward lean of the skier, and consequently on proper jump preparation and technique, and secondarily on strategies to reduce landing height during jumps.
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Färber S, Heinrich D, Werner I, Federolf P. Is it possible to voluntarily increase hamstring muscle activation during landing from a snow jump in alpine skiing? - a pilot study. J Sports Sci 2018; 37:180-187. [PMID: 29912617 DOI: 10.1080/02640414.2018.1488423] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Activation of the hamstrings has been discussed as a measure for reducing strain on the ACL during jump landings in alpine skiing. The current study tested the hypothesis that hamstring and quadriceps activation can be voluntarily increased by the athlete. Specifically, two different instructions - to increase hamstring activation or to increase upper-leg co-contraction - were compared to normal landings. Eight members of the German national and junior national squad in freestyle skiing (age 19.6 ± 3.8 years; weight 66.1 ± 13.2 kg; height 172.2 ± 7.7 cm) performed 12 jump landings on a prepared run, 4 with no specific instruction, 4 with the instruction to generally activate the thigh muscles, and 4 with the instruction to specifically activate the hamstrings. Electromyographic (EMG) signals were recorded on the biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM). EMG activation levels were integrated over three landing phases and analysed with a repeated measures ANOVA. The instruction produced a significant main effect in ST (p = .026), VM (p = .032) and RF (p = .001). Contrary to previous research, the current study suggests that hamstring muscle activation levels can be voluntarily increased during jump landing, particularly in co-activation with its antagonists.
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Affiliation(s)
- Sebastian Färber
- a Department of Sport Science , University of Innsbruck , Innsbruck , Austria, Europe
| | - Dieter Heinrich
- a Department of Sport Science , University of Innsbruck , Innsbruck , Austria, Europe
| | - Inge Werner
- a Department of Sport Science , University of Innsbruck , Innsbruck , Austria, Europe
| | - Peter Federolf
- a Department of Sport Science , University of Innsbruck , Innsbruck , Austria, Europe
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Abstract
Alpine ski racing is known to be a sport with a high risk of injury and a high proportion of time-loss injuries. In recent years, substantial research efforts with regard to injury epidemiology, injury etiology, potential prevention measures, and measures’ evaluation have been undertaken. Therefore, the aims of this review of the literature were (i) to provide a comprehensive overview of what is known about the aforementioned four steps of injury prevention research in the context of alpine ski racing; and (ii) to derive potential perspectives for future research. In total, 38 injury risk factors were previously reported in literature; however, a direct relation to injury risk was proven for only five factors: insufficient core strength/core strength imbalance, sex (depending on type of injury), high skill level, unfavorable genetic predisposition, and the combination of highly shaped, short and wide skis. Moreover, only one prevention measure (i.e. the combination of less-shaped and longer skis with reduced profile width) has demonstrated a positive impact on injury risk. Thus, current knowledge deficits are mainly related to verifying the evidence of widely discussed injury risk factors and assessing the effectiveness of reasonable prevention ideas. Nevertheless, the existing knowledge should be proactively communicated and systematically implemented by sport federations and sport practitioners.
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Gilgien M, Kröll J, Spörri J, Crivelli P, Müller E. Application of dGNSS in Alpine Ski Racing: Basis for Evaluating Physical Demands and Safety. Front Physiol 2018; 9:145. [PMID: 29559918 PMCID: PMC5845727 DOI: 10.3389/fphys.2018.00145] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 02/13/2018] [Indexed: 12/05/2022] Open
Abstract
External forces, such as ground reaction force or air drag acting on athletes' bodies in sports, determine the sport-specific demands on athletes' physical fitness. In order to establish appropriate physical conditioning regimes, which adequately prepare athletes for the loads and physical demands occurring in their sports and help reduce the risk of injury, sport-and/or discipline-specific knowledge of the external forces is needed. However, due to methodological shortcomings in biomechanical research, data comprehensively describing the external forces that occur in alpine super-G (SG) and downhill (DH) are so far lacking. Therefore, this study applied new and accurate wearable sensor-based technology to determine the external forces acting on skiers during World Cup (WC) alpine skiing competitions in the disciplines of SG and DH and to compare these with those occurring in giant slalom (GS), for which previous research knowledge exists. External forces were determined using WC forerunners carrying a differential global navigation satellite system (dGNSS). Combining the dGNSS data with a digital terrain model of the snow surface and an air drag model, the magnitudes of ground reaction forces were computed. It was found that the applied methodology may not only be used to track physical demands and loads on athletes, but also to simultaneously investigate safety aspects, such as the effectiveness of speed control through increased air drag and ski-snow friction forces in the respective disciplines. Therefore, the component of the ground reaction force in the direction of travel (ski-snow friction) and air drag force were computed. This study showed that (1) the validity of high-end dGNSS systems allows meaningful investigations such as characterization of physical demands and effectiveness of safety measures in highly dynamic sports; (2) physical demands were substantially different between GS, SG, and DH; and (3) safety-related reduction of skiing speed might be most effectively achieved by increasing the ski-snow friction force in GS and SG. For DH an increase in the ski-snow friction force might be equally as effective as an increase in air drag force.
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Affiliation(s)
- Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
- St. Moritz Health and Innovation Foundation, Center of Alpine Sports Biomechanics, St. Moritz, Switzerland
| | - Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein, Austria
| | - Jörg Spörri
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein, Austria
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Philip Crivelli
- Group for Snowsports, WSL - Institute for Snow and Avalanche Research SLF, Davos, Switzerland
| | - Erich Müller
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein, Austria
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Vu V, Walker A, Ball N, Spratford W. Ankle restrictive firefighting boots alter the lumbar biomechanics during landing tasks. APPLIED ERGONOMICS 2017; 65:123-129. [PMID: 28802431 DOI: 10.1016/j.apergo.2017.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 06/04/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
Firefighters incur high incidences of lower back and body injuries. Firefighting boots, with specific design requirements, have been shown to reduce ankle range of motion. This reduction has been associated with impaired force dissipation and lower body kinematic alterations. Thus, the aim of this study was to determine the relationship between firefighting boots, lumbar biomechanics and load carriage during landing. Our data indicates that when wearing firefighting boots, lumbar forces increased and kinematics changed in frontal and transverse planes. These changes may be occurring due to the restrictive shaft of the firefighting boot reducing ankle range of motion. Comparisons between unloaded and loaded conditions also showed increased changes in lumbar biomechanics, independent of footwear worn. Therefore, wearing firefighting boots, in addition to operational loading, may be placing firefighters at greater risk of lumbar injuries. Future research investigating firefighting boots and additional load carriage on lower body biomechanics during landing is recommended.
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Affiliation(s)
- Vy Vu
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, Australia
| | - Anthony Walker
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, Australia; Australian Capital Territory Fire and Rescue, Canberra, Australia.
| | - Nick Ball
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, Australia; University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, Australia
| | - Wayne Spratford
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, Australia; University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, Australia
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Spratford W, Vu V, Ball N, Walker A. Protective firefighting boots and their impact on the lower body and injury: A narrative review. ACTA ACUST UNITED AC 2017. [DOI: 10.3233/oer-170246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Wayne Spratford
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| | - Vy Vu
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| | - Nick Ball
- Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, Canberra, ACT, Australia
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| | - Anthony Walker
- University of Canberra Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
- Australian Capital Territory Fire and Rescue, Canberra, ACT, Australia
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Jordan MJ, Aagaard P, Herzog W. Anterior cruciate ligament injury/reinjury in alpine ski racing: a narrative review. Open Access J Sports Med 2017; 8:71-83. [PMID: 28435336 PMCID: PMC5386612 DOI: 10.2147/oajsm.s106699] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The purpose of the present review was to: 1) provide an overview of the current understanding on the epidemiology, etiology, risk factors, and prevention methods for anterior cruciate ligament (ACL) injury in alpine ski racing; and 2) provide an overview of what is known pertaining to ACL reinjury and return to sport after ACL injury in alpine ski racing. Given that most of the scientific studies on ACL injuries in alpine ski racing have been descriptive, and that very few studies contributed higher level scientific evidence, a nonsystematic narrative review was employed. Three scholarly databases were searched for articles on ACL injury or knee injury in alpine ski racing. Studies were classified according to their relevance in relation to epidemiology, etiology, risk factors, and return to sport/reinjury prevention. Alpine ski racers (skiers) were found to be at high risk for knee injuries, and ACL tears were the most frequent diagnosis. Three primary ACL injury mechanism were identified that involved tibial internal rotation and anteriorly directed shear forces from ski equipment and the environment. While trunk muscle strength imbalance and genetics were found to be predictive of ACL injuries in development-level skiers, there was limited scientific data on ACL injury risk factors among elite skiers. Based on expert opinion, research on injury risk factors should focus on equipment design, course settings/speed, and athlete factors (eg, fitness). While skiers seem to make a successful recovery following ACL injury, there may be persistent neuromuscular deficits. Future research efforts should be directed toward prospective studies on ACL injury/reinjury prevention in both male and female skiers and toward the effects of knee injury on long-term health outcomes, such as the early development of osteoarthritis. International collaborations may be necessary to generate sufficient statistical power for ACL injury/reinjury prevention research in alpine ski racing.
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Affiliation(s)
- Matthew J Jordan
- Human Performance Laboratory, The University of Calgary, Calgary, AB, Canada
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense M, Denmark
| | - Walter Herzog
- Human Performance Laboratory, The University of Calgary, Calgary, AB, Canada
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Oberhofer K, Hosseini Nasab SH, Schütz P, Postolka B, Snedeker JG, Taylor WR, List R. The influence of muscle-tendon forces on ACL loading during jump landing: a systematic review. Muscles Ligaments Tendons J 2017; 7:125-135. [PMID: 28717620 PMCID: PMC5505580 DOI: 10.11138/mltj/2017.7.1.125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The goal of this review is to summarise and discuss the reported influence of muscle-tendon forces on anterior cruciate ligament (ACL) loading during the jump-landing task by means of biomechanical analyses of the healthy knee. METHODS A systematic review of the literature was conducted using different combinations of the terms "knee", "ligament", "load", "tension ", "length", "strain", "elongation" and "lengthening". 26 original articles (n=16 in vitro studies; n=10 in situ studies) were identified which complied with all inclusion/exclusion criteria. RESULTS No apparent trend was found between ACL loading and the ratio between hamstrings and quadriceps muscle-tendon forces prior to or during landing. Four in vitro studies reported reduced peak ACL strain if the quadriceps force was increased; while one in vitro study and one in situ study reported reduced ACL loading if the hamstrings force was increased. A meta-analysis of the reported results was not possible because of the heterogeneity of the confounding factors. CONCLUSION The reported results suggest that increased hip flexion during landing may help in reducing ACL strain by lengthening the hamstrings, and thus increasing its passive resistance to stretch. Furthermore, it appears that increased tensile stiffness of the quadriceps may help in stabilising the knee joint during landing, and thus protecting the passive soft-tissue structures from overloading. LEVEL OF EVIDENCE Ib.
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Affiliation(s)
| | | | | | | | - Jess G. Snedeker
- Institute for Biomechanics, ETH Zürich, Switzerland
- University Hospital Balgrist, Zürich, Switzerland
| | | | - Renate List
- Institute for Biomechanics, ETH Zürich, Switzerland
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Abstract
BACKGROUND As the most viable method for investigating in vivo anterior cruciate ligament (ACL) rupture, video analysis is critical for understanding ACL injury mechanisms and advancing preventative training programs. Despite the limited number of published studies involving video analysis, much has been gained through evaluating actual injury scenarios. METHODS Studies meeting criteria for this systematic review were collected by performing a broad search of the ACL literature with use of variations and combinations of video recordings and ACL injuries. Both descriptive and analytical studies were included. RESULTS Descriptive studies have identified specific conditions that increase the likelihood of an ACL injury. These conditions include close proximity to opposing players or other perturbations, high shoe-surface friction, and landing on the heel or the flat portion of the foot. Analytical studies have identified high-risk joint angles on landing, such as a combination of decreased ankle plantar flexion, decreased knee flexion, and increased hip flexion. CONCLUSIONS The high-risk landing position appears to influence the likelihood of ACL injury to a much greater extent than inherent risk factors. As such, on the basis of the results of video analysis, preventative training should be applied broadly. Kinematic data from video analysis have provided insights into the dominant forces that are responsible for the injury (i.e., axial compression with potential contributions from quadriceps contraction and valgus loading). With the advances in video technology currently underway, video analysis will likely lead to enhanced understanding of non-contact ACL injury.
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Affiliation(s)
- Victor R. Carlson
- Functional and Applied Biomechanics, National Institutes of Health, Bethesda, Maryland
| | - Frances T. Sheehan
- Functional and Applied Biomechanics, National Institutes of Health, Bethesda, Maryland
| | - Barry P. Boden
- The Orthopaedic Center, a Division of CAO, Rockville, Maryland
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28
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Gilgien M, Spörri J, Kröll J, Müller E. Effect of ski geometry and standing height on kinetic energy: equipment designed to reduce risk of severe traumatic injuries in alpine downhill ski racing. Br J Sports Med 2016; 50:8-13. [PMID: 26702013 PMCID: PMC4717407 DOI: 10.1136/bjsports-2015-095465] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background Injuries in downhill (DH) are often related to high speed and, therefore, to high energy and forces which are involved in injury situations. Yet to date, no study has investigated the effect of ski geometry and standing height on kinetic energy (EKIN) in DH. This knowledge would be essential to define appropriate equipment rules that have the potential to protect the athletes’ health. Methods During a field experiment on an official World Cup DH course, 2 recently retired world class skiers skied on 5 different pairs of skis varying in width, length and standing height. Course characteristics, terrain and the skiers’ centre of mass position were captured by a differential Global Navigational Satellite System-based methodology. EKIN, speed, ski–snow friction force (FF), ground reaction force (FGRF) and ski–snow friction coefficient (CoeffF) were calculated and analysed in dependency of the used skis. Results In the steep terrain, longer skis with reduced width and standing height significantly decreased average EKIN by ∼3%. Locally, even larger reductions of EKIN were observed (up to 7%). These local decreases in EKIN were mainly explainable by higher FF. Moreover, CoeffF differences seem of greater importance for explaining local FF differences than the differences in FGRF. Conclusions Knowing that increased speed and EKIN likely lead to increased forces in fall/crash situations, the observed equipment-induced reduction in EKIN can be considered a reasonable measure to improve athlete safety, even though the achieved preventative gains are rather small and limited to steep terrain.
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Affiliation(s)
- Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Jörg Spörri
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
| | - Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
| | - Erich Müller
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
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29
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Thoreson O, Kovac P, Swärd A, Agnvall C, Todd C, Baranto A. Back pain and MRI changes in the thoraco-lumbar spine of young elite Mogul skiers. Scand J Med Sci Sports 2016; 27:983-989. [PMID: 27367529 DOI: 10.1111/sms.12710] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2016] [Indexed: 11/30/2022]
Abstract
Athletes have a higher prevalence of LBP and spinal abnormalities on Magnetic Resonance Imaging (MRI) compared to non-athletes. The objective of this study was to investigate the amount of spinal MRI abnormalities and the lifetime prevalence of low back pain (LBP) in 16 young elite Mogul skiers compared to 28 non-athletes in the corresponding age in a cross-sectional design. LBP was assessed by a questionnaire consisting of a part regarding previous or present back pain, the Oswestry disability index, and the EuroQol questionnaire. MRI examinations from Th5 to sacrum were conducted to evaluate spinal pathologies. The Mogul skiers had significantly more MRI abnormalities (like disc degeneration) in mean (7.25 vs 3.78, P < 0.023) compared to the controls. No significant difference was seen regarding the lifetime LBP prevalence between the groups (50% vs 42%, P = 0.555). No correlation could be found between disc degeneration and back pain in this study. Young elite Mogul skiers, compared to an age-matched control group of non-athletes, have an increased risk of developing spinal abnormalities potentially due to the different high loads that they are subjected to in their sport. Future relationship between the MRI abnormalities and LBP cannot be verified by this study design.
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Affiliation(s)
- O Thoreson
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - P Kovac
- Radiology, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - A Swärd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden.,Sportsmedicine Åre and Åre Ski High School, Åre, Sweden
| | - C Agnvall
- Sportsmedicine Åre and Åre Ski High School, Åre, Sweden
| | - C Todd
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden.,The Carl Todd Clinic, Corsham, UK
| | - A Baranto
- Department of Orthopaedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
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Gilgien M, Crivelli P, Spörri J, Kröll J, Müller E. Characterization of course and terrain and their effect on skier speed in World Cup alpine ski racing. PLoS One 2015; 10:e0118119. [PMID: 25760039 PMCID: PMC4356573 DOI: 10.1371/journal.pone.0118119] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 01/08/2015] [Indexed: 11/18/2022] Open
Abstract
World Cup (WC) alpine ski racing consists of four main competition disciplines (slalom, giant slalom, super-G and downhill), each with specific course and terrain characteristics. The International Ski Federation (FIS) has regulated course length, altitude drop from start to finish and course setting in order to specify the characteristics of the respective competition disciplines and to control performance and injury-related aspects. However to date, no detailed data on course setting and its adaptation to terrain is available. It is also unknown how course and terrain characteristics influence skier speed. Therefore, the aim of the study was to characterize course setting, terrain geomorphology and their relationship to speed in male WC giant slalom, super-G and downhill. The study revealed that terrain was flatter in downhill compared to the other disciplines. In all disciplines, variability in horizontal gate distance (gate offset) was larger than in gate distance (linear distance from gate to gate). In giant slalom the horizontal gate distance increased with terrain inclination, while super-G and downhill did not show such a connection. In giant slalom and super-G, there was a slight trend towards shorter gate distances as the steepness of the terrain increased. Gates were usually set close to terrain transitions in all three disciplines. Downhill had a larger proportion of extreme terrain inclination changes along the skier trajectory per unit time skiing than the other disciplines. Skier speed decreased with increasing steepness of terrain in all disciplines except for downhill. In steep terrain, speed was found to be controllable by increased horizontal gate distances in giant slalom and by shorter gate distances in giant slalom and super-G. Across the disciplines skier speed was largely explained by course setting and terrain inclination in a multiple linear model.
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Affiliation(s)
- Matthias Gilgien
- Norwegian School of Sport Sciences, Department of Physical Performance, Oslo, Norway
| | - Philip Crivelli
- WSL—Institute for Snow and Avalanche Research SLF, Group for Snowsports, Davos, Switzerland
| | - Jörg Spörri
- University of Salzburg, Department of Sport Science and Kinesiology, Hallein-Rif, Austria
| | - Josef Kröll
- University of Salzburg, Department of Sport Science and Kinesiology, Hallein-Rif, Austria
| | - Erich Müller
- University of Salzburg, Department of Sport Science and Kinesiology, Hallein-Rif, Austria
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