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Feuerriegel GC, Marth AA, Fröhlich S, Scherr J, Spörri J, Sutter R. Superolateral Hoffa fat pad edema in adolescent competitive alpine skiers: temporal evolution over 4 years and risk factors. Insights Imaging 2024; 15:52. [PMID: 38365902 PMCID: PMC10873258 DOI: 10.1186/s13244-024-01633-8] [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: 11/14/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024] Open
Abstract
OBJECTIVES To longitudinally assess and correlate the prevalence of superolateral Hoffa fat pad (SHFP) edema with changes in features of the knee extensor mechanism in adolescent competitive alpine skiers over 48 months. METHODS Competitive alpine skiers were prospectively enrolled in 2018 and underwent bilateral knee MRI at baseline and after 48 months. MRI was assessed for the prevalence of SHFP edema. Features of the knee extensor mechanism were assessed by measuring the trochlear sulcus angle and depth, lateral and medial trochlear inclination, trochlear angle, patella tilt, Insall‒Salvati ratio (ISR), and patellar ligament to lateral trochlear facet (PL-T) distance. Separate logistic regression models were used to calculate the odds ratios between each measurement and the presence of SHFP edema at both time points. RESULTS Sixty-three athletes were included in the study (mean age 15.3 ± 1.3 years, 25 women). At baseline, 23 knees had SHFP edema, increasing to 34 knees at the 48-month follow-up. At baseline, knees with measurements in the highest quartile for ISR and lowest quartile for trochlear depth and PL-T were 9.3, 5.1, and 7.7 times more likely to show SHFP edema, respectively. At follow-up, these correlations were confirmed and additionally, knees with measurements in the highest quartile for trochlear sulcus angle and the lowest quartile for lateral trochlear inclination were 4.1 and 3.4 times more likely to show SHFP edema. CONCLUSION An increased prevalence of SHFP edema in competitive alpine skiers during adolescence was associated with persistent high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet. CRITICAL RELEVANCE STATEMENT In clinical routine, assessment of the mechanical properties of the knee extensor mechanism, together with anatomical developments during adolescence, may improve the understanding and management of patellofemoral instability. KEY POINTS • Superolateral Hoffa fat pad (SHFP) edema is a frequent cause of anterolateral knee pain but the role of predisposing factors is still debated. • A higher prevalence of SHFP edema was associated with high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet. • Understanding of the mechanical interaction and the anatomical development of the knee during adolescence provides further insight into the development of SHFP edema.
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Affiliation(s)
- Georg C Feuerriegel
- Department of Radiology, Faculty of Medicine, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
| | - Adrian A Marth
- Department of Radiology, Faculty of Medicine, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Swiss Center for Musculoskeletal Imaging, Balgrist Campus AG, Zurich, Switzerland
| | - Stefan Fröhlich
- 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
| | - Johannes Scherr
- 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
| | - Reto Sutter
- Department of Radiology, Faculty of Medicine, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
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Chollet M, Delhaye C, Samozino P, Bowen M, Morel B, Monjo F, Hintzy F. The "velocity barrier" in giant slalom skiing: An experimental proof of concept. Scand J Med Sci Sports 2024; 34:e14515. [PMID: 37837209 DOI: 10.1111/sms.14515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 09/22/2023] [Accepted: 09/28/2023] [Indexed: 10/15/2023]
Abstract
BACKGROUND Alpine skiing involves the conversion of potential energy into kinetic energy, with the "velocity barrier" (VB) at each moment corresponding to the maximal velocity at which the athlete can ski while staying within the boundaries of the gates and maintaining control. Nevertheless, this concept has never been proven by evidence. The aim of this study was to experimentally test the existence of the VB and clarify its relationship with skier's force production/application capacities. METHODS Fourteen skiers were equipped with ski-mounted force plates and a positional device and ran a 2-turn Giant Slalom section starting from eight different heights on the slope. Three conditions were selected for further analysis: minimal entrance velocity (vmin ); entrance velocity allowing the better section time (VB); maximal entrance velocity (vmax ). Entrance velocity, section time, mean force output, ratio of force application effectiveness, velocity normalized energy dissipation, and path length were compared between the three conditions. Moreover, skier's mechanical energy and velocity curves were compared all along the section between the three conditions using SPM analysis. RESULTS The section time was reduced in VB compared to vmin (p < 0.001) and vmax (p = 0.002). Skiers presented an incapacity to increase force output beyond the VB (p = 0.441) associated with a lower force application effectiveness (p = 0.005). Maximal entrance velocity was associated to higher energy dissipation (p < 0.001) and path length (p = 0.005). CONCLUSION The present study experimentally supports the existence of the VB. The force production/application capacities seem to limit the skiing effectiveness beyond the VB, associated to increased energy dissipations and path length.
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Affiliation(s)
- Mickael Chollet
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Clément Delhaye
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Pierre Samozino
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Maximilien Bowen
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Baptiste Morel
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Florian Monjo
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
| | - Frédérique Hintzy
- Inter-University Laboratory of Human Movement Sciences, Université Savoie Mont Blanc, Chambéry, France
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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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Meinke A, Spörri J, Brogli L, Schwab P, Karlen W. Addressing the unresolved challenge of quantifying skiing exposure-A proof of concept using smartphone sensors. Front Sports Act Living 2023; 5:1157987. [PMID: 37229363 PMCID: PMC10203200 DOI: 10.3389/fspor.2023.1157987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 04/21/2023] [Indexed: 05/27/2023] Open
Abstract
In epidemiological studies related to winter sports, especially alpine skiing, an unresolved methodological challenge is the quantification of actual on-snow activity exposure. Such information would be relevant for reporting meaningful measures of injury incidence, which refers to the number of new injuries that occur in a given population and time period. Accordingly, accurate determination of the denominator, i.e., actual "activity exposure time", is critical for injury surveillance and reporting. In this perspective article, we explore the question of whether wearable sensors in combination with mHealth applications are suitable tools to accurately quantify the periods in a ski day when the skier is physically skiing and not resting or using a mechanical means of transport. As a first proof of concept, we present exemplary data from a youth competitive alpine skier who wore his smartphone with embedded sensors on his body on several ski days during one winter season. We compared these data to self-reported estimates of ski exposure, as used in athletes' training diaries. In summary, quantifying on-snow activity exposure in alpine skiing using sensor data from smartphones is technically feasible. For example, the sensors could be used to track ski training sessions, estimate the actual time spent skiing, and even quantify the number of runs and turns made as long as the smartphone is worn. Such data could be very useful in determining actual exposure time in the context of injury surveillance and could prove valuable for effective stress management and injury prevention in athletes.
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Affiliation(s)
- Anita Meinke
- Mobile Health Systems Lab, Institute of Robotics and Intelligent Systems, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - 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
| | - Luzius Brogli
- Mobile Health Systems Lab, Institute of Robotics and Intelligent Systems, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Patrick Schwab
- Mobile Health Systems Lab, Institute of Robotics and Intelligent Systems, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Walter Karlen
- Mobile Health Systems Lab, Institute of Robotics and Intelligent Systems, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Institute of Biomedical Engineering, University of Ulm, Ulm, Germany
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Hanimann J, Ellenberger L, Bernhard T, Franchi MV, Roth R, Faude O, Spörri J. More than just a side effect: Dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers have similar absolute values and asymmetry magnitudes but differ in terms of the direction of laterality. Front Physiol 2023; 14:1129351. [PMID: 36969591 PMCID: PMC10031042 DOI: 10.3389/fphys.2023.1129351] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/21/2023] [Indexed: 03/11/2023] Open
Abstract
From a preventative perspective, leg axis and core stabilization capacities are important for soccer players and alpine skiers; however, due to different sport-specific demands, the role of laterality clearly differs and may result in functional long-term adaptations. The aims of this study are 1) to determine whether there are differences in leg axis and core stability between youth soccer players and alpine skiers and 2) between dominant and non-dominant sides, and 3) to explore the outcomes of applying common sport-specific asymmetry thresholds to these two distinct cohorts. Twenty-one highly trained/national-level soccer players (16.1 years, 95% CI: 15.6, 16.5) and 61 alpine skiers (15.7 years, 95% CI: 15.6, 15.8) participated in this study. Using a marker-based 3D motion capture system, dynamic knee valgus was quantified as the medial knee displacement (MKD) during drop jump landings, and core stability was quantified as the vertical displacement during deadbug bridging exercise (DBBdisplacement). For the analysis of sports and side differences, a repeated-measures multivariate analysis of variance was used. For the interpretation of laterality, coefficients of variation (CV) and common asymmetry thresholds were applied. There were no differences in MKD or DBBdisplacement between soccer players and skiers or between the dominant and non-dominant sides, but there was an interaction effect side*sports for both variables (MKD: p = 0.040, η2p = 0.052; DBBdisplacement: p = 0.025, η2p = 0.061). On average, MKD was larger on the non-dominant side and DBBdisplacement laterality on the dominant side in soccer players, whereas this pattern was reversed in alpine skiers. Despite similar absolute values and asymmetry magnitudes of dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers, the effect on the direction of laterality was opposite even though much less pronounced. This may imply that sport-specific demands and potential laterality advantages should be considered when dealing with asymmetries in athletes.
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Affiliation(s)
- Jonas Hanimann
- 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
- *Correspondence: Jonas Hanimann,
| | - Lynn Ellenberger
- 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
- Swiss Council for Accident Prevention BFU, Bern, Switzerland
| | - Thomas Bernhard
- Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland
- FC Basel 1893, Basel, Switzerland
| | - Martino V. Franchi
- Institute of Physiology, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ralf Roth
- Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland
| | - Oliver Faude
- Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland
| | - 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
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Spörri J, Müller E, Kröll J. "When you're down, stay down": A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo. JOURNAL OF SPORT AND HEALTH SCIENCE 2022; 11:14-20. [PMID: 34852295 PMCID: PMC8847912 DOI: 10.1016/j.jshs.2021.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/02/2021] [Accepted: 11/16/2021] [Indexed: 05/31/2023]
Abstract
BACKGROUND During an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective. METHODS Eight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography of 4 relevant muscle groups, inertial measurement units to measure knee and hip angles, and pressure insoles to determine ground reaction forces. RESULTS Due to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL. CONCLUSION Our example emphasizes that ski racers should not get up until they stop sliding. Remember: "When you're down, stay down."
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Affiliation(s)
- Jörg Spörri
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich 8008, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich 8008, Switzerland.
| | - Erich Müller
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Ri 5400, Austria
| | - Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Ri 5400, Austria
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Kiers K, Kröll J, Mitterbauer G, Scherr J, Spörri J. Perceptions of experts on key injury risk factors in alpine ski racing as a function of stakeholder role and associated level of competition. BMJ Open Sport Exerc Med 2021; 7:e001111. [PMID: 34603741 PMCID: PMC8449969 DOI: 10.1136/bmjsem-2021-001111] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2021] [Indexed: 11/04/2022] Open
Abstract
Objectives (1) To update experts' priorities of perceived key injury risk factors in alpine ski racing based on a framework and list derived 10 years ago, (2) to identify additionally emerging risk factors since then and (3) to compile a list with countermeasure suggestions. Methods A sample of 532 expert stakeholders (athletes, coaches, team medical staff, Ski Racing Suppliers (SRS) and International Ski Federation (FIS) representatives) from the World Cup (WC), European Cup (EC) and FIS-race level participated in a cross-sectional online survey. Experts were asked to name those risk factors with the highest believed impact on injury risk and rank them according to their current priority from a predefined list. In addition, experts were encouraged to name additional (not listed) risk factors and to suggest countermeasures. Results Regardless of stakeholder role and competition level, snow-related factors appeared to have the highest perceived priority. However, WC athletes' and coaches' perceptions were also related to equipment, while at the EC and FIS-race level fatigue and physical fitness-related factors were considered important. Athletes' perceptions were largely in agreement with SRS (ie, snow-related and equipment-related factors). At the same time, while coaches, team medical staff and FIS representatives additionally emphasised fatigue and physical fitness-related factors. Conclusion Experts' perceptions on key injury risk factors in alpine ski racing depend on the stakeholder role and differ between the competition levels. Thus, to develop effective prevention measures and to successfully implement them, all relevant stakeholders should be given a voice, and prevention efforts should be targeted to the specific level.
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Affiliation(s)
- Kirsten Kiers
- 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
| | - Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria
| | - Gerald Mitterbauer
- Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria
| | - 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
| | - 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
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Ellenberger L, Casutt S, Fröhlich S, Frey WO, Snedeker JG, Spörri J. Thigh muscle activation patterns and dynamic knee valgus at peak ground reaction force during drop jump landings: Reliability, youth competitive alpine skiing-specific reference values and relation to knee overuse complaints. J Sci Med Sport 2021; 24:1230-1234. [PMID: 34238661 DOI: 10.1016/j.jsams.2021.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/19/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVES (1) To evaluate the reliability of quantifying thigh muscle activation patterns and dynamic knee valgus during drop jump landings, (2) to provide reference values for female and male youth alpine skiers, and (3) to study their associations with age, anthropometrics, biological maturation and knee overuse complaints. DESIGN Cross-sectional biomechanical experiment including questionnaires. METHODS One hundred fourteen skiers of the under 16 category (main experiment) and twelve healthy participants (reliability experiment) volunteered. Quadriceps-to-hamstring-activation ratio and medial knee displacementat peak ground reaction force during drop jump landings were measured using marker-based motion analysis, force plates and electromyography. Additionally, age, anthropometrics, biological maturation and knee overuse complaints were assessed. RESULTS There were good test-retest reliabilities and moderate standardized typical errors for both quadriceps-to-hamstring-activation ratio (intraclass correlation coefficient(3,1) = 0.84 [95% confidence interval: 0.69, 0.94]; standardized typical errors = 0.43 [0.35, 0.56]) and medial knee displacement (intraclass correlation coefficient(3,1) = 0.87 [0.74, 0.95]; standardized typical errors = 0.39 [0.32, 0.50]). Male skiers had a significantly higher quadriceps-to-hamstring-activation ratio (3.9 ± 2.0 vs. 2.9 ± 1.4, p = 0.011), whilst medial knee displacement was comparable to females (12 mm ± 11 mm vs. 13 mm ± 9 mm; p = 0.419). In male skiers, medial knee displacement correlated with anthropometrics and maturity offset; in female skiers, quadriceps-to-hamstring-activation ratio and medial knee displacement were associated with knee overuse complaints (p < 0.05). CONCLUSIONS Female and male youth skiers use different thigh muscle activation strategies, but show comparable dynamic knee valgus motions during drop jump landings. In females, a combination of increased relative quadriceps activity and medial knee displacement may favour knee overuse complaints.
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Affiliation(s)
- Lynn Ellenberger
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
| | - Selina Casutt
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
| | - Stefan Fröhlich
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
| | - Walter O Frey
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
| | - Jess G Snedeker
- Biomechanics Laboratory, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; Institute for Biomechanics, ETH Zurich, Switzerland.
| | - Jörg Spörri
- Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland; Motion Analysis Zurich, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Switzerland.
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Injury prevention in Super-G alpine ski racing through course design. Sci Rep 2021; 11:3637. [PMID: 33574431 PMCID: PMC7878813 DOI: 10.1038/s41598-021-83133-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/11/2021] [Indexed: 11/08/2022] Open
Abstract
In Super-G alpine ski racing mean speed is nearly as high as in Downhill. Hence, the energy dissipated in typical impact accidents is similar. However, unlike Downhill, on Super-G courses no training runs are performed. Accordingly, speed control through course design is a challenging but important task to ensure safety in Super-G. In four male World Cup alpine Super-G races, terrain shape, course setting and the mechanics of a high-level athlete skiing the course were measured with differential global navigation satellite systems (dGNSS). The effects of course setting on skier mechanics were analysed using a linear mixed effects model. To reduce speed by 0.5 m/s throughout a turn, the gate offset needs to be increased by + 51%. This change simultaneously leads to a decrease in minimal turn radius (− 19%), an increase in impulse (+ 27%) and an increase in maximal ground reaction force (+ 6%). In contrast, the same reduction in speed can also be achieved by a − 13% change in vertical gate distance, which also leads to a small reduction in minimal turn radius (− 4%) impulse (− 2%), and no change in maximal ground reaction force; i.e. fewer adverse side effects in terms of safety. It appears that shortening the vertical gate distance is a better and safer way to reduce speed in Super-G than increasing the gate offset.
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Xu Y, Yang C, Yang Y, Zhang X, Zhang S, Zhang M, Liu L, Fu W. A Narrative Review of Injury Incidence, Location, and Injury Factor of Elite Athletes in Snowsport Events. Front Physiol 2021; 11:589983. [PMID: 33488394 PMCID: PMC7820716 DOI: 10.3389/fphys.2020.589983] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/10/2020] [Indexed: 11/13/2022] Open
Abstract
Snowsport athletes face a high injury risk both during training and in competitions. Reducing injury incidence is crucial for athletes to achieve breakthroughs. This narrative review aimed to summarize and analyze injury data of elite athletes in snowsports and provide references for injury prevention and health security for these athletes and their coaches. A total of 39 studies that investigated snowsport injury were analyzed in the present study. On the basis of injury data of elite athletes in snowsports events, this narrative review focused on four aspects, namely, injury incidence, severity, location and causes. The findings of this review were as follows. (1) The highest injury incidence was recorded in freestyle skiing, followed by alpine skiing and snowboarding, the majority of which were moderate and severe injuries. (2) The proportion of injury in competitions and during training was similar. However, more injuries occurred in official training during the Winter Olympic Games; by contrast, injury proportion was higher in competitions during World Cup/World Championships. (3) The most commonly and severely injured body parts were the knees (29.9%), head and face (12.1%), shoulders and clavicula (10.5%), and lower back (8.9%). The most common injury types were joint and ligament injury (41.5%), fracture and bone stress (24.4%), concussion (11.1%), and muscle/tendon injury (10.7%). (4) The main causes of snowsport injury were collisions, falls, and non-contact injuries. Snowsport injury was also influenced by the skill level of the athletes, gender, course setup and equipment. Future studies should further explore the influence of event characteristics and intrinsic and extrinsic risk factors on snowsport injury. An injury or trauma reconstruction may be developed to predict athletic injuries and provide effective prevention strategies.
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Affiliation(s)
- Yongxin Xu
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Chenhao Yang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Yang Yang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Xini Zhang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Shen Zhang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Mingwen Zhang
- Beijing Institute of Fashion Technology, Beijing, China.,Institute for Frontier Materials, Deakin University, Geelong, VIC, Australia
| | - Li Liu
- Beijing Institute of Fashion Technology, Beijing, China
| | - Weijie Fu
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
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11
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Martínez A, Nakazato K, Scheiber P, Snyder C, Stöggl T. Comparison of the Turn Switch Time Points Measured by Portable Force Platforms and Pressure Insoles. Front Sports Act Living 2020; 2:2. [PMID: 33344997 PMCID: PMC7739759 DOI: 10.3389/fspor.2020.00002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/06/2020] [Indexed: 11/17/2022] Open
Abstract
Several methods to determine turn switch points during alpine skiing using the vertical GRF exist in the literature. Although comparative studies between pressure insoles (PI) and force platforms (FP) have been conducted, there are no reports comparing the detected time points. Yet, these sensors and methods have been used interchangeably. This study aims to compare the turn switch time points with both sensors and various methods. Twenty skiers performed turns with FP and PI for two different ski styles (high and low dynamic turns). Three different assessment methodologies were compared: minima, functional minima, and crossings. Bland Altman and repeated measures ANOVA were used to assess statistical differences. Main effects of sensor and method were observed (p < 0.001). Although there was a low effect size (ηp2 = 0.013) between FP and PI, the 95% CI yielded values representing >30% of the turn duration. A large effect size (η2 = 0.153) was found between the crossing method and the minima and functional minima methods. This indicates that those methods assess different events during the turn switch phase. In conclusion, the sensors and assessment methodologies compared in this study are not interchangeable with the possible exception of the minima and functional minima assessed with FP.
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Affiliation(s)
- Aaron Martínez
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
| | - Kosuke Nakazato
- Faculty of Information Media, Hokkaido Information University, Ebetsu, Japan
| | - Peter Scheiber
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
| | - Cory Snyder
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
| | - Thomas Stöggl
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria
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12
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Petrone N, Vanzetto D, Marcolin G, Bruhin B, Gilgien M. The effect of foot setting on kinematic and kinetic skiing parameters during giant slalom: A single subject study on a Paralympic gold medalist sit skier. J Sci Med Sport 2020; 24:1049-1054. [PMID: 32998849 DOI: 10.1016/j.jsams.2020.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 04/04/2020] [Accepted: 08/26/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Aim was to study the effect of monoski foot adjustment on kinematic and kinetic skiing parameters expressing sit skier's technique. DESIGN Independent variable was skier position with respect to bindings, acting on position of monoski foot sole clamp. Front (F), Mid (M) and Rear (R) settings changed with intervals of 20mm. Course time, skiing speed, Ground Reaction Forces (GRFs) magnitude and point of application and damper stroke were dependent variables. METHOD A Paralympic monoski was equipped with a dynamometric binding plate measuring GRFs, roll and pitch moments. A Paralympic gold medalist (LW10-1) was involved. Skier trajectory and gates location were measured by a differential global navigation satellite system (GNSS) in steep and medium steep slope portions. The athlete performed two giant slalom runs for each foot setting the same day. RESULTS GRFs, center of pressure (COP) and variations with foot settings were measured. Peaks values up to 3.36 times the total weight and damper speed of 675mm/s in compression were found. Fastest runs, highest peak loads and best subjective ratings were recorded with F setting. COP mean values were influenced by foot adjustments. GRFs in left turns were 54% larger than in the right turns with F setting on steep slope. CONCLUSIONS The monoski foot adjustment influenced kinematic and kinetic skiing, with F setting showing best results. A skier asymmetric behavior between right and left turning was discovered. Findings can support the design of monoskis for a wider dissemination of Paralympic alpine sit skiing.
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Affiliation(s)
- Nicola Petrone
- Department of Industrial Engineering, University of Padova, Italy.
| | - Dario Vanzetto
- Department of Industrial Engineering, University of Padova, Italy
| | | | - Björn Bruhin
- Swiss-Ski, Switzerland; Section for Elite Sport, Swiss Federal Institute of Sport Magglingen, Switzerland
| | - Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, Norway; Center of Alpine Sports Biomechanics, Engadin Health and Innovation Foundation, Switzerland
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13
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Fröhlich S, Peterhans L, Stern C, Frey WO, Sutter R, Spörri J. Remarkably high prevalence of overuse-related knee complaints and MRI abnormalities in youth competitive alpine skiers: a descriptive investigation in 108 athletes aged 13-15 years. BMJ Open Sport Exerc Med 2020; 6:e000738. [PMID: 32537242 PMCID: PMC7264838 DOI: 10.1136/bmjsem-2020-000738] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2020] [Indexed: 12/13/2022] Open
Abstract
Background/aim Competitive alpine skiing is known to be associated with a high risk of traumatic knee injuries. However, little is known about the exact prevalence of knee overuse injuries and their associations with structural changes, particularly in youth skiers. Accordingly, the aim of the present study was to describe the overuse-related knee complaints and MRI abnormalities in a cohort of youth skiers around the growth spurt. Methods 108 youth competitive alpine skiers aged 13–15 years were examined using an MRI of both knees, an interview on existing knee complaints and a physical examination. As a common baseline for these assessments, skiers were prospectively monitored by the use of the Oslo Sports Trauma Research Centre questionnaire on health problems over a period of 12 months preceding the major investigations. Results 88.0% of the youth skiers showed at least one MRI abnormality in the knees. The most frequent findings were distal femoral cortical irregularities (63%), focal periphyseal oedema (FOPE) zones (25.0%) and cartilage lesions (18.5%). 47.2% of all skiers suffered from at least one overuse-related knee complaint during the 12 months preceding the MRI examination, mostly at the distal and proximal patellar tendon. However, despite a certain association with corresponding MRI abnormalities, the sensitivity of an MRI-based detection of such complaints was strongly limited. Conclusion Youth competitive alpine skiers suffer from a remarkably large number of knee overuse injuries. Accordingly, an effective prevention strategy should include a systematic screening of clinical complaints, ideally already starting around the growth spurt.
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Affiliation(s)
- Stefan Fröhlich
- 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
| | - Loris Peterhans
- 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
| | - Christoph Stern
- Department of Radiology, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Walter O Frey
- University Centre for Prevention and Sports Medicine, Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Reto Sutter
- Department of Radiology, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - 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
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14
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Reid RC, Haugen P, Gilgien M, Kipp RW, Smith GA. Alpine Ski Motion Characteristics in Slalom. Front Sports Act Living 2020; 2:25. [PMID: 33345019 PMCID: PMC7739813 DOI: 10.3389/fspor.2020.00025] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/04/2020] [Indexed: 11/13/2022] Open
Abstract
Important insight into ski function, and ultimately skier technique and tactics, can be gained by studying how measured ski trajectories compare to predictions based on theoretical models of ski-snow interaction mechanics. The aim of this investigation was to use a 3D kinematic data set collected on highly-skilled skiers during slalom race simulations to quantify ski motion characteristics and to compare these measures with theoretical predictions based primarily on ski geometrical characteristics. For slalom turns on moderate steepness (19°), ski edging angles reached maximum values of 65.7 ± 1.7° and 71.0 ± 1.9° for 10 and 13 m gate spacings. Turn radii reached minimum values of 3.96 ± 0.23 and 4.94 ± 0.59 m for the 10 and 13 m courses. These values were in good agreement with theoretical predictions by Howe (2001) of turn radius based on edging angle. Other results of the study support recent developments in understanding of the role which the ski shovel plays in groove formation during carving, and also point to the need for further study of how ski geometrical and physical characteristics interact to determine the ski's trajectory, particularly at low edge angles. These results have important implications for understanding the consequences that ski design can have for skier technique and tactics in competitive slalom skiing.
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Affiliation(s)
- Robert C Reid
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Alpine Skiing, Norwegian Ski Federation, Oslo, Norway
| | - Per Haugen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Alpine Skiing, Norwegian Ski Federation, Oslo, Norway
| | - Ronald W Kipp
- Independent Researcher, Squaw Valley, CA, United States
| | - Gerald Allen Smith
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Colorado Mesa University, Grand Junction, CO, United States
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15
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Supej M, Holmberg HC. Recent Kinematic and Kinetic Advances in Olympic Alpine Skiing: Pyeongchang and Beyond. Front Physiol 2019; 10:111. [PMID: 30842740 PMCID: PMC6391578 DOI: 10.3389/fphys.2019.00111] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 01/30/2019] [Indexed: 11/13/2022] Open
Abstract
Alpine skiing has been an Olympic event since the first Winter Games in 1936. Nowadays, skiers compete in four main events: slalom, giant slalom, super-G and downhill. Here, we present an update on the biomechanics of alpine ski racers and their equipment. The technical and tactical ability of today’s world-class skiers have adapted substantially to changes in equipment, snow conditions and courses. The wide variety of terrain, slopes, gate setups and snow conditions involved in alpine skiing requires skiers to continuously adapt, alternating between the carving and skidding turning techniques. The technical complexity places a premium on minimizing energy dissipation, employing strategies and ski equipment that minimize ski-snow friction and aerodynamic drag. Access to multiple split times along the racing course, in combination with analysis of the trajectory and speed provide information that can be utilized to enhance performance. Peak ground reaction forces, which can be as high as five times body weight, serve as a measure of the external load on the skier and equipment. Although the biomechanics of alpine skiing have significantly improved, several questions concerning optimization of skiers’ performance remain to be investigated. Recent advances in sensor technology that allow kinematics and kinetics to be monitored can provide detailed information about the biomechanical factors related to success in competitions. Moreover, collection of data during training and actual competitions will enhance the quality of guidelines for training future Olympic champions. At the same time, the need to individualize training and skiing equipment for each unique skier will motivate innovative scientific research for years to come.
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Affiliation(s)
- Matej Supej
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
| | - H-C Holmberg
- The Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden.,School of Sport Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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16
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Tarka MC, Davey A, Lonza GC, O'Brien CM, Delaney JP, Endres NK. Alpine Ski Racing Injuries. Sports Health 2019; 11:265-271. [PMID: 30689522 DOI: 10.1177/1941738119825842] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
CONTEXT This article reviews the epidemiology of alpine ski racing-related injuries, risk factors, mechanisms of injury, and injury prevention strategies. EVIDENCE ACQUISITION Pertinent literature from peer-reviewed publications from 1976 through 2018. STUDY DESIGN Clinical review. LEVEL OF EVIDENCE Level 5. RESULTS The rate of injury in alpine ski racing is high. In general, knee injuries are the most common, with anterior cruciate ligament (ACL) disruptions being the most significant in terms of time loss from sport. Three specific mechanisms of ACL injury in alpine ski racers have recently been described (slip-catch, dynamic snowplow, and landing back-weighted). In contrast to other sports, female ski racers are not clearly at greater risk for ACL injury, especially at the highest level of competition. A high percentage of ski racers are able to return to their previous level of competition after ACL injury. Risk factors for injury and methods of injury prevention have been proposed; however, the rate of injury, particularly ACL injuries, has not decreased significantly. CONCLUSION Alpine ski racing has a high injury rate. ACL injuries in particular remain problematic. Further study is needed to identify modifiable risk factors and implementation of injury prevention strategies.
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Affiliation(s)
- Mitchell C Tarka
- Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont
| | - Annabelle Davey
- Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Geordie C Lonza
- Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Casey M O'Brien
- Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts
| | - John P Delaney
- Cleveland Clinic Orthopaedic and Rheumatologic Institute, Cleveland, Ohio
| | - Nathan K Endres
- Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont
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17
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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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18
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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: 5.5] [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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19
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Spörri J, Kröll J, Fasel B, Aminian K, Müller E. Standing Height as a Prevention Measure for Overuse Injuries of the Back in Alpine Ski Racing: A Kinematic and Kinetic Study of Giant Slalom. Orthop J Sports Med 2018; 6:2325967117747843. [PMID: 29344540 PMCID: PMC5761919 DOI: 10.1177/2325967117747843] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background In alpine ski racing, typical loading patterns of the back include a combined occurrence of spinal bending, torsion, and high peak loads. These factors are known to be associated with high spinal disc loading and have been suggested to be attributable to different types of spine deterioration. However, little is known about the effect of standing height (ie, the distance between the bottom of the running surface of the ski and the ski boot sole) on the aforementioned back loading patterns. Purpose To investigate the effect of reduced standing height on the skier's overall trunk kinematics and the acting ground-reaction forces in giant slalom (GS) from an overuse injury prevention perspective. Study Design Controlled laboratory study. Methods Seven European Cup-level athletes skied a total of 224 GS turns with 2 different pairs of skis varying in standing height. Their overall trunk movement (frontal bending, lateral bending, and torsion angles) was measured based on 2 inertial measurement units located at the sacrum and sternum. Pressure insoles were used to determine the total ground-reaction force. Results During the turn phase in which the greatest spinal disc loading is expected to occur, significantly lower total ground-reaction forces were observed for skis with a decreased standing height. Simultaneously, the skier's overall trunk movement (ie, frontal bending, lateral bending, and torsion angles) remained unwaveringly high. Conclusion Standing height is a reasonable measure to reduce the skier's overall back loading in GS. Yet, when compared with the effects achievable by increased gate offsets in slalom, for instance, the preventative benefits of decreased standing height seem to be rather small. Clinical Relevance To reduce the magnitude of overall back loading in GS and to prevent overuse injuries of the back, decreasing standing height might be an efficient approach. Nevertheless, the clinical relevance of the current findings, as well as the effectiveness of the measure "reduced standing height," must be verified by epidemiological studies before its preventative potential can be judged as conclusive.
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Affiliation(s)
- Jörg Spörri
- Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.,Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria
| | - Benedikt Fasel
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Kamiar Aminian
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Erich Müller
- Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria
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20
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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: 32] [Impact Index Per Article: 4.6] [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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21
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Fasel B, Sporri J, Chardonnens J, Kroll J, Muller E, Aminian K. Joint Inertial Sensor Orientation Drift Reduction for Highly Dynamic Movements. IEEE J Biomed Health Inform 2017; 22:77-86. [PMID: 28141537 DOI: 10.1109/jbhi.2017.2659758] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Inertial sensor drift is usually corrected on a single-sensor unit level. When multiple sensor units are used, mutual information from different units can be exploited for drift correction. This study introduces a method for a drift-reduced estimation of three dimensional (3-D) segment orientations and joint angles for motion capture of highly dynamic movements as present in many sports. 3-D acceleration measured on two adjacent segments is mapped to the connecting joint. Drift is estimated and reduced based on the mapped accelerations' vector orientation differences in the global frame. Algorithm validity is assessed on the example of alpine ski racing. Shank, thigh, and trunk inclination as well as knee and hip flexion were compared to a multicamera-based reference system. For specific leg angles and trunk segment inclination mean accuracy and precision were below 3.9° and 6.0°, respectively. The errors were similar to errors reported in other studies for lower dynamic movements. Drift increased axis misalignment and mainly affected joint and segment angles of highly flexed joints such as the knee or hip during a ski turn.
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22
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Kröll J, Spörri J, Gilgien M, Schwameder H, Müller E. Sidecut radius and kinetic energy: equipment designed to reduce risk of severe traumatic knee injuries in alpine giant slalom ski racing. Br J Sports Med 2016; 50:26-31. [PMID: 26702015 PMCID: PMC4717412 DOI: 10.1136/bjsports-2015-095463] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background Kinetic energy (Ekin) increases with speed by the power of 2 and is considered a major risk factor for injuries in alpine ski racing. There is no empirical knowledge about the effect of ski geometry on Ekin. Consequently, the aim of this study was to investigate the influence of sidecut radius on the progress of Ekin while skiing through a multigate section in giant slalom (GS). Methods 5 European-Cup level athletes skied on three different pairs of GS skis varying in sidecut radii (30, 35 and 40 m). Each athlete's position over time within a six gate section (including flat and steep terrain) was captured by the use of a differential Global Navigational Satellite System. Ekin, speed, time and path length were analysed for each pair of skis used. Results When using skis with greater sidecut radius, average Ekin was significantly lower over the entire six gate section, but not locally at every turn cycle. Particular decreases of Ekin were observed for both turns on the flat terrain, as well as for the turn at the terrain transition and the first turn on the steep terrain. The observed decreases in Ekin were found to be primarily explainable by increases in turn time. Conclusions With respect to typical sport mechanisms that cause severe knee injuries, using skis with greater sidecut radius potentially provides additional injury preventative gain, particularly in specific areas within a run. However, this injury preventative gain during falls in GS should not be overestimated.
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Affiliation(s)
- Josef Kröll
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
| | - Jörg Spörri
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
| | - Matthias Gilgien
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Hermann Schwameder
- 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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23
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Müller E, Spörri J, Kröll J, Hörterer H. Equipment designed to reduce risk of severe traumatic injuries in alpine ski racing: constructive collaboration between the International Ski Federation, industry and science. Br J Sports Med 2016; 50:1-2. [PMID: 26702012 DOI: 10.1136/bjsports-2015-095689] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Erich Müller
- Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria
| | - 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
| | - Hubert Hörterer
- Medical Committee, International Ski Federation (FIS), Oberhofen, Switzerland
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24
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Three-Dimensional Body and Centre of Mass Kinematics in Alpine Ski Racing Using Differential GNSS and Inertial Sensors. REMOTE SENSING 2016. [DOI: 10.3390/rs8080671] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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