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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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2
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Bjerke Ø, Lorås H, Pedersen AV. Constituent Year Effects and Performance in Alpine Skiing Junior World Championships. Sports (Basel) 2023; 11:155. [PMID: 37624135 PMCID: PMC10457790 DOI: 10.3390/sports11080155] [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: 02/16/2023] [Revised: 05/08/2023] [Accepted: 08/14/2023] [Indexed: 08/26/2023] Open
Abstract
This study examines constituent year effect (CYE) and race performance among junior alpine skiers in the World Championships. In various junior age cohorts competing together, variation in skiing performance can be expected not only due to practice load and experience but also due to inter-individual differences in physical and psychological maturation. Within a one-year cohort, this effect has been referred to as the birth month effect or the relative age effect (RAE). In cohorts with multiple age bands, the effect is termed the constituent year effect (CYE). The CYE works in principle as the RAE but can function as a magnifying lens of the development within a larger multi-year cohort. The results of the current study indicate that CYEs are present among junior alpine skier performance in the junior World Championships. The magnitude of the constituent year effect is greater in speed events (i.e., downhill and super-G) than in technical events (i.e., slalom and giant slalom), and greater among male skiers compared to female skiers. The findings are discussed in relation to previous research on relative age effects more generally and within the sport context specifically.
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Affiliation(s)
- Øyvind Bjerke
- Department of Teacher Education, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Håvard Lorås
- Department of Teacher Education, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Arve Vorland Pedersen
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, 7030 Trondheim, Norway
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3
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Rizzato A, Verdel N, Paoli A, Supej M, Marcolin G. Sport-specific balance tests account for youth alpine skiers' ranking. Front Physiol 2023; 14:1205347. [PMID: 37546541 PMCID: PMC10398384 DOI: 10.3389/fphys.2023.1205347] [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: 04/13/2023] [Accepted: 07/10/2023] [Indexed: 08/08/2023] Open
Abstract
Objective: Alpine skiing requires complex motor skills and fine adjustments to maintain balance in dynamic and challenging conditions. This study aimed to understand whether the balance ability in unspecific (UST) and sport-specific (SST) tasks could depend on the skiers' ranking level. The balance performance of the dominant and non-dominant limbs in the SST was also investigated. Methods: Twenty-five skiers (14.96 ± 1.61 yrs; 1.69 ± 0.69 m; 59.9 ± 9.52 kg) were divided into high-ranking (position < 50) and low-ranking (position > 50) groups. Subjects performed three balance conditions: static (ST), dynamic UST, and dynamic SST. Subjects stood on an unstable board over a force platform during UST. During SST, subjects wore ski boots, grasped ski poles, and each foot was clipped to an unstable board over two force plates. From the center-of-pressure (CoP) trajectory the area of the 95th percentile ellipse and the CoP mean velocity were calculated. Angular displacements were recorded by a 12-camera system, to calculate the full balance (FB), fine (FiB), and gross (GB) balance in UST and SST. Results: Balance control was higher (p < 0.01) in high-ranking than low-ranking skiers only in the SST. Kinematic parameters (i.e., FB, FiB, and GB) showed a higher (p < 0.001) balance performance in SST than UST independently from the group. Dominant and non-dominant limbs motion was similar (Pearson correlation, r = 0.97) in SST independently from the skiers' ranking. Conclusion: High-ranking skiers showed better balance control and performance than low-ranking skiers only when the task was sport-specific. Therefore, we suggest testing balance under sport-specific conditions to discriminate the youth skiers' abilities.
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Affiliation(s)
- Alex Rizzato
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Nina Verdel
- Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
| | - Antonio Paoli
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Matej Supej
- Faculty of Sports, University of Ljubljana, Ljubljana, Slovenia
| | - Giuseppe Marcolin
- Department of Biomedical Sciences, University of Padova, Padua, Italy
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4
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Li B, Li P, Zhang Y, Jia K, Hong P. Effect of ambient wind on the performance of alpine downhill skier. Sci Rep 2023; 13:4906. [PMID: 36966191 PMCID: PMC10039862 DOI: 10.1038/s41598-023-32107-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 03/21/2023] [Indexed: 03/27/2023] Open
Abstract
Alpine skiing, especially alpine downhill, is one of the most extreme winter sports in terms of high-speed and narrow winning margin, and its tracks are always located in mountainous areas with high altitudes and complex ambient wind fields, resulting in a significant impact of ambient wind on the performance and the final ranking of alpine downhill skiers. In the present study, a method based upon the combination of field measurements, wind tunnel tests and kinematic simulations was used to evaluate the effect of ambient wind on the performance of an alpine downhill skier. Considering the effect of ambient wind, a kinematic model of the alpine skier-ski system was established, and the equations of motion for straight gliding and turning were deduced. Then, the Chinese National Alpine Ski Center (CNASC) downhill track was taken as a case study to investigate the effect of ambient wind on the gliding time using the proposed combined evaluation method. Field measurements and wind tunnel tests were performed to identify five critical ambient wind directions of 270°, 292.5°, 315°, 337.5° and 360°. Moreover, the wind speeds and the wind directions for 16 different measurement points of the downhill track were also obtained. The results of the modelling analysis showed that the finish time increased by 19.75% for the ambient wind direction of 270°, whereas the finish time decreased by 1.29% for the ambient wind direction of 360°.
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Affiliation(s)
- Bo Li
- School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China.
- Beijing's Key Laboratory of Structural Wind Engineering and Urban Wind Environment, Beijing, 100044, China.
| | - Peng Li
- School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China
| | - Yuanzhao Zhang
- School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China
| | - Kun Jia
- School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China
| | - Ping Hong
- Beijing Sport University, Beijing, 100084, China.
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Azadi B, Haslgrübler M, Anzengruber-Tanase B, Grünberger S, Ferscha A. Alpine Skiing Activity Recognition Using Smartphone's IMUs. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22155922. [PMID: 35957479 PMCID: PMC9371385 DOI: 10.3390/s22155922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/01/2022] [Accepted: 08/05/2022] [Indexed: 06/12/2023]
Abstract
Many studies on alpine skiing are limited to a few gates or collected data in controlled conditions. In contrast, it is more functional to have a sensor setup and a fast algorithm that can work in any situation, collect data, and distinguish alpine skiing activities for further analysis. This study aims to detect alpine skiing activities via smartphone inertial measurement units (IMU) in an unsupervised manner that is feasible for daily use. Data of full skiing sessions from novice to expert skiers were collected in varied conditions using smartphone IMU. The recorded data is preprocessed and analyzed using unsupervised algorithms to distinguish skiing activities from the other possible activities during a day of skiing. We employed a windowing strategy to extract features from different combinations of window size and sliding rate. To reduce the dimensionality of extracted features, we used Principal Component Analysis. Three unsupervised techniques were examined and compared: KMeans, Ward's methods, and Gaussian Mixture Model. The results show that unsupervised learning can detect alpine skiing activities accurately independent of skiers' skill level in any condition. Among the studied methods and settings, the best model had 99.25% accuracy.
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Affiliation(s)
- Behrooz Azadi
- Pro2Future GmbH, Altenberger Strasse 69, 4040 Linz, Austria
| | | | | | - Stefan Grünberger
- Institute of Pervasive Computing, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| | - Alois Ferscha
- Institute of Pervasive Computing, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
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6
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Alhammoud M, Girard O, Hansen C, Racinais S, Meyer F, Hautier CA, Morel B. Repeated practice runs during on-snow training do not generate any measurable neuromuscular alterations in elite alpine skiers. Front Sports Act Living 2022; 4:829195. [PMID: 35966108 PMCID: PMC9372580 DOI: 10.3389/fspor.2022.829195] [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: 12/05/2021] [Accepted: 06/28/2022] [Indexed: 11/26/2022] Open
Abstract
Background Alpine skiers typically train using repeated practice runs requiring high bursts of muscle activity but there is little field-based evidence characterizing neuromuscular function across successive runs. Purpose To examine the impact of repeated ski runs on electromyographic activity (EMG) of the knee extensors and flexors in elite alpine skiers. Methods Nineteen national team alpine skiers were tested during regular ski training [Slalom (SL), Giant Slalom (GS), Super Giant Slalom and Downhill (Speed)] for a total of 39 training sessions. The surface EMG of the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) and semimembranosus/semitendinosus (SMST) muscles was continuously recorded along with right knee and hip angles. The EMG root mean square signal was normalized to a maximal voluntary contraction (%MVC). The first and fourth runs of the training session were compared. Results There was no meaningful main effect of run on EMG relative activation time or mean power frequency beyond the skier's intrinsic variability. However, EMG activity of the vastii increased from the first to the fourth run in SL [VM, ~+3%MVC for IL and outside leg (OL), p = 0.035)], speed (VL, IL:+6%/OL:+11%, p = 0.015), and GS (VM, IL:0/OL:+7%, p < 0.001); the later with an interaction with leg (p < 0.001) due to a localized increase on the OL. The run time and turn time did not change from the first to the fourth run. There were no meaningful changes in angular velocities, amplitude of movement, or maximal and minimal angles. Conclusion Neuromuscular activity remains highly stable in elite skiers with low variability across four runs.
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Affiliation(s)
- Marine Alhammoud
- Aspetar–Orthopaedic and Sports Medicine Hospital, Doha, Qatar
- French Ski Federation, Annecy, France
- *Correspondence: Marine Alhammoud
| | - Olivier Girard
- School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, WA, Australia
| | - Clint Hansen
- Department of Neurology, Christian-Albrechts-Universität zu Kiel Medizinische Fakultat, Kiel, Germany
| | | | - Frédéric Meyer
- Digital Signal Processing Group, Department of Informatics, University of Oslo, Oslo, Norway
| | - Christophe André Hautier
- Inter-University Laboratory of Human Movement Biology, University Claude Bernard Lyon 1, Lyon, France
| | - Baptiste Morel
- Inter-University Laboratory of Human Movement Biology (EA 7424), Savoie Mont Blanc University, Chambéry, France
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7
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Application of Experimental Measurements in a Wind Tunnel to the Development of a Model for Aerodynamic Drag on Elite Slalom and Giant Slalom Alpine Skiers. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aerodynamic drag is a major cause of energy losses during alpine ski racing. Here we developed two models for monitoring the aerodynamic drag on elite alpine skiers in the technical disciplines. While 10 skiers assumed standard positions (high, middle, tuck) with exposure to different wind speeds (40, 60, and 80 km/h) in a wind tunnel, aerodynamic drag was assessed with a force plate, shoulder height with video-based kinematics, and cross-sectional area with interactive image segmentation. The two regression models developed had 3.9–7.7% coefficients of variation and 4.5–16.5% relative limits of agreement. The first was based on the product of the coefficient of aerodynamic drag and cross-sectional area (Cd∙S) and the second on the coefficient of aerodynamic drag Cd and normalized cross-sectional area of the skier Sn, both expressed as a function of normalized shoulder height (hn). In addition, normative values for Cd (0.75 ± 0.09–1.17 ± 0.09), Sn (0.51 ± 0.03–0.99 ± 0.05), hn (0.48 ± 0.03–0.79 ± 0.02), and Cd∙S (0.23 ± 0.03–0.66 ± 0.09 m2) were determined for the three different positions and wind speeds. Since the uncertainty in the determination of energy losses due to aerodynamic drag relative to total energy loss with these models is expected to be <2.5%, they provide a valuable tool for analysis of skiing performance.
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8
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Bortolan L, Savoldelli A, Pellegrini B, Modena R, Sacchi M, Holmberg HC, Supej M. Ski Mountaineering: Perspectives on a Novel Sport to Be Introduced at the 2026 Winter Olympic Games. Front Physiol 2021; 12:737249. [PMID: 34744777 PMCID: PMC8566874 DOI: 10.3389/fphys.2021.737249] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/20/2021] [Indexed: 11/13/2022] Open
Abstract
Ski mountaineering is a rapidly growing winter sport that involves alternately climbing and descending slopes and various racing formats that differ in length and total vertical gain, as well as their distribution of downhill and uphill sections. In recent years, both participation in and media coverage of this sport have increased dramatically, contributing, at least in part, to its inclusion in the 2026 Winter Olympics in Milano-Cortina. Here, our aim has been to briefly describe the major characteristics of ski mountaineering, its physiological and biomechanical demands, equipment, and training/testing, as well as to provide some future perspectives. Despite its popularity, research on this discipline is scarce, but some general characteristics are already emerging. Pronounced aerobic capacity is an important requirement for success, as demonstrated by positive correlations between racing time and maximal oxygen uptake and oxygen uptake at the second ventilatory threshold. Moreover, due to the considerable mechanical work against gravity on demanding uphill terrain, the combined weight of the athlete and equipment is inversely correlated with performance, prompting the development of both lighter and better equipment in recent decades. In ski mountaineering, velocity uphill is achieved primarily by more frequent (rather than longer) strides due primarily to high resistive forces. The use of wearable technologies, designed specifically for analysis in the field (including at elevated altitudes and cold temperatures) and more extensive collaboration between researchers, industrial actors, and coaches/athletes, could further improve the development of this sport.
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Affiliation(s)
- Lorenzo Bortolan
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Aldo Savoldelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Barbara Pellegrini
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Roberto Modena
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.,CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | | | | | - Matej Supej
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
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Pérez-Chirinos Buxadé C, Fernández-Valdés B, Morral-Yepes M, Tuyà Viñas S, Padullés Riu JM, Moras Feliu G. Validity of a Magnet-Based Timing System Using the Magnetometer Built into an IMU. SENSORS 2021; 21:s21175773. [PMID: 34502664 PMCID: PMC8433996 DOI: 10.3390/s21175773] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/16/2022]
Abstract
Inertial measurement units (IMUs) represent a technology that is booming in sports right now. The aim of this study was to evaluate the validity of a new application on the use of these wearable sensors, specifically to evaluate a magnet-based timing system (M-BTS) for timing short-duration sports actions using the magnetometer built into an IMU in different sporting contexts. Forty-eight athletes (22.7 ± 3.3 years, 72.2 ± 10.3 kg, 176.9 ± 8.5 cm) and eight skiers (17.4 ± 0.8 years, 176.4 ± 4.9 cm, 67.7 ± 2.0 kg) performed a 60-m linear sprint running test and a ski slalom, respectively. The M-BTS consisted of placing several magnets along the course in both contexts. The magnetometer built into the IMU detected the peak-shaped magnetic field when passing near the magnets at a certain speed. The time between peaks was calculated. The system was validated with photocells. The 95% error intervals for the total times were less than 0.077 s for the running test and 0.050 s for the ski slalom. With the M-BTS, future studies could select and cut the signals belonging to the other sensors that are integrated in the IMU, such as the accelerometer and the gyroscope.
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Affiliation(s)
- Carla Pérez-Chirinos Buxadé
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
| | - Bruno Fernández-Valdés
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
- School of Health Sciences, TecnoCampus, Pompeu Fabra University, 08302 Barcelona, Spain
| | - Mónica Morral-Yepes
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
| | - Sílvia Tuyà Viñas
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
| | - Josep Maria Padullés Riu
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
| | - Gerard Moras Feliu
- National Institute of Physical Education of Catalonia (INEFC), University of Barcelona (UB), 08038 Barcelona, Spain; (C.P.-C.B.); (B.F.-V.); (M.M.-Y.); (S.T.V.); (J.M.P.R.)
- Correspondence:
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Ogrin J, Šarabon N, Madsen MK, Kersting U, Holmberg HC, Supej M. Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength. Front Physiol 2021; 12:577698. [PMID: 33859567 PMCID: PMC8042208 DOI: 10.3389/fphys.2021.577698] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 03/12/2021] [Indexed: 12/24/2022] Open
Abstract
The ground reaction forces (GRF) associated with competitive alpine skiing, which are relatively large, might be asymmetric during left and right turns due to asymmetries in the strength of the legs and torso and the present investigation was designed to evaluate this possibility. While skiing a symmetrical, 20-gate slalom course, the asymmetries of 9 elite alpine skiers were calculated on the basis of measurements provided by inertial motion units (IMU), a Global Navigation Satellite System and pressure insoles. In addition, specialized dynamometers were utilized to assess potential asymmetry in the strength of their legs and torso in the laboratory. In total, seven variables related to GRF were assessed on-snow and eight related to strength of the legs and torso in the laboratory. The asymmetries in these parameters between left and right turns on snow were expressed in terms of the symmetry (SI) and Jaccard indices (JI), while the asymmetries between the left and right sides of the body in the case of the laboratory measurements were expressed as the SIs. The three hypotheses to be tested were examined using multivariable regression models. Our findings resulted in rejection of all three hypotheses: The asymmetries in total GRF (H1), as well as in the GRF acting on the inside and outside legs (H2) and on the rear- and forefeet GRF (H3) during left and right turns were not associated with asymmetries in parameters related to muscular strength. Nevertheless, this group of elite slalom skiers exhibited significant asymmetry between their right and left legs with respect to MVC during ankle flexion (0.53 ± 0.06 versus 0.60 ± 0.07 Nm/kg, respectively) and hip extension (2.68 ± 0.39 versus 2.17 ± 0.26 Nm/kg), as well as with respect to the GRFs on the inside leg while skiing (66.8 ± 7.39 versus 76.0 ± 10.0 %BW). As indicated by the JI values, there were also large asymmetries related to GRF as measured by pressure insoles (range: 42.7–56.0%). In conclusion, inter-limb asymmetries in GRFs during elite alpine skiing are not related to corresponding asymmetries in muscular strength. Although our elite athletes exhibited relatively small inter-limb asymmetries in strength, their asymmetries in GRF on-snow were relatively large.
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Affiliation(s)
- Jan Ogrin
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
| | - Nejc Šarabon
- Faculty of Health Sciences, University of Primorska, Izola, Slovenia.,S2P, Science to Practice, Ltd., Laboratory for Motor Control and Motor Behavior, Ljubljana, Slovenia
| | - Mads Kjær Madsen
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark
| | - Uwe Kersting
- Department of Health Science and Technology, Sport Sciences - Performance and Technology, Aalborg University, Aalborg, Denmark.,Institute of Biomechanics and Orthopedics, German Sport University Cologne, Cologne, Germany
| | - Hans-Christer Holmberg
- Department of Physiology and Pharmacology, Biomedicum C5, Karolinska Institute, Stockholm, Sweden.,China Institute of Sport and Health Science, Beijing Sport University, Beijing, China
| | - Matej Supej
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.,Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
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11
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Performance Parameters in Competitive Alpine Skiing Disciplines of Slalom, Giant Slalom and Super-Giant Slalom. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18052628. [PMID: 33807931 PMCID: PMC7967377 DOI: 10.3390/ijerph18052628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/23/2021] [Accepted: 03/02/2021] [Indexed: 11/21/2022]
Abstract
The objective of this study was to describe the kinematic patterns and impacts in male and female skiers in the super-giant slalom, giant slalom and slalom disciplines of an international alpine skiing competition using a portable Global Navigation Satellite Systems (GNSS) technology device. Fifteen skiers (males, n = 9, females, n = 6) volunteered to participate in this study. Data acquisition was carried out using a wireless inertial measurement device (WIMUTM PRO: hybrid location system GNSS at 18 Hz with a precision locator UltraWideband UWD (<10 cm) and 3D accelerometers 1000 Hz) where distances covered in different speed and acceleration thresholds and impacts above 5g were recorded in each of the disciplines. Male and female alpine skiers showed different physical parameters and impacts even though they competed in the same courses in the disciplines of slalom, giant slalom and super-giant slalom (total impacts: p < 0.001; impacts > 7 g: p = 0.013; impacts 6.1–7 g: p = 0.002; impacts 5.1–6 g: p = 0.006). In male skiers, the distances traveled at different speed thresholds have a direct relation to the ranking of skiers, but this ideal threshold decreased as the technicality of the discipline increased. In the case of female skiers, although no relation was seen with the speed thresholds, greater distances covered at medium accelerations improved skiing performance. The external load in alpine skiing varied based on sex and discipline. This information could be essential to develop sex-specific and discipline-specific training programs in alpine skiing.
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Cross MR, Delhaye C, Morin JB, Bowen M, Coulmy N, Hintzy F, Samozino P. Force output in giant-slalom skiing: A practical model of force application effectiveness. PLoS One 2021; 16:e0244698. [PMID: 33444398 PMCID: PMC7808649 DOI: 10.1371/journal.pone.0244698] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 12/14/2020] [Indexed: 01/30/2023] Open
Abstract
Alpine ski racers require diverse physical capabilities. While enhanced force production is considered key to high-level skiing, its relevance is convoluted. The aims of this study were to i) clarify the association between performance path length and velocity, ii) test the importance of radial force, and iii) explore the contribution of force magnitude and orientation to turn performance. Ski athletes (N = 15) were equipped with ski-mounted force plates and a global navigation satellite system to compute the following variables over 14 turns: path length (L), velocity normalized energy dissipation [Δemech/vin], radial force [Fr], total force (both limbs [Ftot], the outside limb, and the difference between limbs), and a ratio of force application (RF = Fr/Ftot). Data were course-averaged or separated into sectional turn groupings, averaged, and entered into stepped correlation and regression models. Our results support Δemech/vin as a discriminative performance factor (R2 = 0.50-0.74, p < .003), except in flat sections. Lower course times and better Δemech/vin were associated with greater Fr (R2 = 0.34-0.69 and 0.31-0.52, respectively, p < .032), which was related to both Ftot and RF (β = 0.92-1.00 and 0.63-0.81, respectively, p < .001) which varied in predictive order throughout the sections. Ftot was associated with increased outside limb force and a more balanced contribution of each limb (β = 1.04-1.18 and -0.65- -0.92, respectively, p < .001). Fr can be improved by either increasing total force output or by increasing technical effectiveness (i.e., proportionally more force radially) which should increase the trajectories available to the skier on the ski course.
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Affiliation(s)
- Matt R. Cross
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
- Département Scientifique et Sportif, Fédération Française de Ski, Annecy, France
| | - Clément Delhaye
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
| | - Jean-Benoit Morin
- Inter-University Laboratory of Human Movement Biology, Univ Lyon, UJM-Saint-Etienne, Saint-Étienne, France
| | - Maximilien Bowen
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
| | - Nicolas Coulmy
- Département Scientifique et Sportif, Fédération Française de Ski, Annecy, France
| | - Frédérique Hintzy
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
| | - Pierre Samozino
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Chambéry, France
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Cross MR, Rivière JR, Coulmy N, Morin JB, Samozino P. Lower limb force-production capacities in alpine skiing disciplines. Scand J Med Sci Sports 2020; 31:848-860. [PMID: 33259106 DOI: 10.1111/sms.13897] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/20/2020] [Accepted: 11/27/2020] [Indexed: 11/29/2022]
Abstract
Specific force capacities might be a limiting factor for alpine skiing performance, yet there is little consensus on the capabilities in question, and whether they differ between disciplines. We aimed to test discipline (speed and technical) and performance (event-specific world standing) effects on lower limb force-production qualities. National-level skiers (N = 31) performed loaded squat jumps and isometric mid-thigh pulls to detect dynamic force output at extremely low and high velocities and maximum isometric force and rate of force development, respectively. Discipline differences were assessed via a general linear model including performance and allowing for interaction effects, with performance associations further characterized via distinct Pearson's correlations. Jump height did not differentiate disciplines, with absolute power slightly higher in speed athletes (F(1,27) = 4.42, P = .045, ω2 = 0.10), and neither variables were related to performance. Speed athletes possessed greater dynamic force at low velocities (F0 ; F(1,27) = 13.8, P < .001, ω2 = 0.17), and greater relative and absolute maximum isometric force (F(1,25) = 11.19-20.70, ω2 = 0.16-0.22, P < .003). Overall, higher ranked athletes possessed more force-dominant profiles (F(1,27) = 16.28, ω2 = 0.34; r = 0.60 to 0.67, P < .001) and increased rate of force development characteristics (average and maximum, r = -0.50 to -0.82, P < .048). Very robust associations existed between maximum isometric force and speed performance (r = -0.88, P < .001), but only a trend for higher absolute isometric force in technical athletes (r = -0.49, P = .052). Alpine skiers display a preponderance for dynamic force output at low velocities, and isometric force for speed athletes, which highlights the interest in specific assessment and conditioning practices for ski athletes.
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Affiliation(s)
- Matthew R Cross
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Le Bourget du Lac, France.,Département Scientifique et Sportif, Fédération Française de Ski, Annecy, France.,Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Jean Romain Rivière
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Le Bourget du Lac, France
| | - Nicolas Coulmy
- Département Scientifique et Sportif, Fédération Française de Ski, Annecy, France
| | - Jean-Benoit Morin
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.,Inter-university Laboratory of Human Movement Biology, Université Jean Monnet, Saint-Étienne, France
| | - Pierre Samozino
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, Le Bourget du Lac, France
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Delhaye C, Cross MR, Bowen M, Samozino P, Hintzy F. Influence of Line Strategy Between Two Turns on Performance in Giant Slalom. Front Sports Act Living 2020; 2:589257. [PMID: 33345162 PMCID: PMC7739777 DOI: 10.3389/fspor.2020.589257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/19/2020] [Indexed: 11/13/2022] Open
Abstract
In alpine ski racing, different line choices can drastically affect turn or sectional performance. The straight-line transition between two turns is the main phase where skiers can gain speed in a race, open their trajectory, or reduce their path length. Between two turns, a skier can foster speed increase by spending more time in a straight line, inducing sharper turning phases (Z strategy). Inversely, speed can be conserved during the entire turn cycle by performing long curved turns separated by a short straight line (S strategy). This research aimed to evaluate the kinetic and kinematic specificities associated with the line strategy and to explore interactions of selected strategy with skier performance and energy dissipation. A mixed-level population of male alpine skiers (n = 17) skied a timed giant-slalom course while equipped with specialized force plates and a positional device collecting synchronized normal ground reaction force and position-time data, respectively. Time of edge switch was computed from the force signal as the period with the lowest force application on the outside ski. From positional data, turn cycles were separated into turning and straight-line phases (radius bellow and above 30 m, respectively). Time length, path length in the straight line, speed amplitude, and change in specific mechanical energy were computed for each turn and averaged for each skier. The path length during straight line was used to continuously characterize the line strategy within the spectrum between the Z (long straight line) and S (short straight line) strategy. Path length in the straight line was correlated with the amplitude of speed over a straight line (r = 0.672, p = 0.003) and relative and absolute time spent in the straight line (r = 0.967, p < 0.001). However, path length in straight line was not correlated with decrease of speed in the following turn (r = -0.418, p = 0.390) or time without force application on the outside ski (r = 0.195, p = 0.453). While higher-performing athletes on the course performed turns during which they dissipated less energy when normalized to entry speed (r = -0.620, p = 0.008), it appears they did so with variable turn strategies approaches.
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Affiliation(s)
- Clément Delhaye
- Univ. Savoie Mont Blanc, Inter-University Laboratory of Human Movement Biology, Chambéry, France
| | - Matthew R. Cross
- Univ. Savoie Mont Blanc, Inter-University Laboratory of Human Movement Biology, Chambéry, France
- Département Scientifique et Sportif, Fédération Française de Ski, Annecy, France
| | - Maximilien Bowen
- Univ. Savoie Mont Blanc, Inter-University Laboratory of Human Movement Biology, Chambéry, France
| | - Pierre Samozino
- Univ. Savoie Mont Blanc, Inter-University Laboratory of Human Movement Biology, Chambéry, France
| | - Frédérique Hintzy
- Univ. Savoie Mont Blanc, Inter-University Laboratory of Human Movement Biology, Chambéry, France
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15
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Asymmetries in the Technique and Ground Reaction Forces of Elite Alpine Skiers Influence Their Slalom Performance. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10207288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background: Although many of the movements of skiers are asymmetric, little is presently known about how such asymmetry influences performance. Here, our aim was to examine whether asymmetries in technique and the ground reaction forces associated with left and right turns influence the asymmetries in the performance of elite slalom skiers. Methods: As nine elite skiers completed a 20-gate slalom course, their three-dimensional full-body kinematics and ground reaction forces (GRF) were monitored with a global navigation satellite and inertial motion capture systems, in combination with pressure insoles. For multivariable regression models, 26 predictor skiing techniques and GRF variables and 8 predicted skiing performance variables were assessed, all of them determining asymmetries in terms of symmetry and Jaccard indices. Results: Asymmetries in instantaneous and sectional performance were found to have the largest predictor coefficients associated with asymmetries in shank angle and hip flexion of the outside leg. Asymmetry for turn radius had the largest predictor coefficients associated with asymmetries in shank angle and GRF on the entire outside foot. Conclusions: Although slalom skiers were found to move their bodies in a quite symmetrical fashion, asymmetry in their skiing technique and GRF influenced variables related to asymmetries in performance.
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DeCouto BS, Fawver B, Taylor T, Williams AM. Physical fitness is associated with better technical performance in adolescent alpine ski racers after controlling for practice time: A retrospective regression analysis. J Sports Sci 2020; 39:380-387. [PMID: 32951530 DOI: 10.1080/02640414.2020.1823088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In an effort to evaluate the mechanisms underpinning performance in alpine ski racing, researchers have focused on the predictive validity of measures derived from fitness assessments. However, a limitation of this literature is the absence of practice time, since prolonged training may naturally develop specific fitness capacities, making some tests of physical ability less predictive of performance. We examine the relationship between fitness tests, practice, and performance using linear regressions with fitness test data, practice history data, and performance results from adolescent alpine ski racers attending professional development academies in the United States (N = 82). Only aerobic capacity (i.e. 20 m shuttle run) was significantly associated with more practice time. After controlling for practice hours, 5.5-6.5% of variance in ski performance was significantly explained by assessments of lower body power (i.e. standing long jump, triple jump), anaerobic capacity (i.e. 60 s box jump), and upper body strength/endurance (i.e. push-ups). Findings highlight the important role of anaerobic power on alpine ski racing performance, which may be developed outside of regular practice, possibly through weight training or physical maturation. The small variance explained by physical/physiological measures suggests that superior ski performance is likely a product of various skills and characteristics (e.g. technical, tactical, perceptual-cognitive, psychosocial).
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Affiliation(s)
- Brady S DeCouto
- Department of Health and Kinesiology, University of Utah, College of Health , Salt Lake City, UT, USA
| | - Brad Fawver
- Department of Health and Kinesiology, University of Utah, College of Health , Salt Lake City, UT, USA
| | - Troy Taylor
- United States Ski & Snowboard , Park City, UT, USA
| | - Andrew Mark Williams
- Department of Health and Kinesiology, University of Utah, College of Health , Salt Lake City, UT, USA
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17
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Yang C, Xu Y, Yang Y, Xiao S, Fu W. Effectiveness of Using Compression Garments in Winter Racing Sports: A Narrative Review. Front Physiol 2020; 11:970. [PMID: 32848885 PMCID: PMC7417664 DOI: 10.3389/fphys.2020.00970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/16/2020] [Indexed: 01/03/2023] Open
Abstract
Nowadays, compression garments (CGs) are widely used in winter racing sports, such as speed skating, short-track speed skating, alpine skiing, and cross-country skiing. However, the effect of wearing CGs on athletic performance in these specific sports is still not fully examined. Thus, the aim of this narrative review is to summarize the research and application of CGs in winter racing sports and to discuss how the CGs help athletes improve their performance in an integrative manner (i.e., physiology, aerodynamics, and biomechanics). A total of 18 experimental studies dedicated to CGs in winter racing sports were identified from the peer-review scientific literature. The main findings are as follows. (1) Currently, CG studies have mainly focused on drag reduction, metabolism, muscle function, strength performance, and fatigue recovery. (2) The results of most studies conducted in wind tunnels showed that, for cylindrical structures similar to the human body, clothing with rough surfaces can reduce air drag. Notably, the effect of CGs on drag reduction in real competition has not been fully explored in the literature. (3) Compression can reduce muscle vibrations at high impact and help athletes control the center of pressure movement, a function that is important for alpine skiing. Future studies are needed to improve current understanding of the effects of compression clothing microstructure on drag reduction and their stretching in different parts of the body. Furthermore, the design of experimental protocol must be consistent with those during the competition, thus providing a full discussion on energy metabolism, fatigue, and recovery affected by CGs.
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Affiliation(s)
- Chenhao Yang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Yongxin Xu
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Yang Yang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Songlin Xiao
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Weijie Fu
- School of Kinesiology, Shanghai University of Sport, Shanghai, China.,Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China
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18
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Alhammoud M, Hansen C, Meyer F, Hautier C, Morel B. On-Field Ski Kinematic According to Leg and Discipline in Elite Alpine Skiers. Front Sports Act Living 2020; 2:56. [PMID: 33345047 PMCID: PMC7739787 DOI: 10.3389/fspor.2020.00056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 04/20/2020] [Indexed: 11/23/2022] Open
Abstract
This study used wireless technology to investigate joint kinematic characteristics of the four alpine skiing disciplines. Knee and hip angles were measured in 20 national team alpine skiers during 253 ski runs under FIS regulation, including: 85 Slalom (SL), 123 Giant Slalom (GS), 29 Super Giant Slalom (SG), and 16 Downhill (DH). Data were analyzed by outside (OL, n = 2,087) and inside leg (IL, n = 2,015). The proportion of concentric and eccentric phases (extension and flexion respectively for the knee extensors) as well as the proportion of the quasi-isometric phase defined between ±20°.s−1 depended on the discipline in interaction with the IL/OL (p < 0.001). The results showed a lower knee quasi-isometric duration on OL in SL (11%) than other disciplines (DH: 38%; SG: 42%; GS: 34%, p < 0.001, d > 1.8), suggesting a highly dynamic style. Quasi-isometric mode was significantly longer on OL than IL in GS (34 vs. 20%, p < 0.001, d = 1.16) and SG (42 vs. 28%, p < 0.001, d = 1.11) but was significantly longer on IL than OL in SL (19 vs. 11%, p < 0.001, d = 0.64). Thus, GS and SG showed similarities, with a significantly faster knee eccentric mean angular velocity on IL compared to OL (GS −58 vs. −54°.s−1, SG −52 vs. −45°.s−1, p < 0.001, d ≥ 0.22) whereas SL showed an opposite pattern (−72 vs. −89°.s−1, p < 0.001, d = 1.10). The quasi-isometric phase was overlooked in previous studies but is crucial to consider. The current data may be used to train the outside and inside leg specificities incorporating discipline-specific contraction modes and exercises.
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Affiliation(s)
- Marine Alhammoud
- French Ski Federation, Annecy, France.,Inter-University Laboratory of Human Movement Biology (EA 7424), University Claude Bernard Lyon 1, Lyon, France.,Surgery Department, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Clint Hansen
- Department of Neurology, Christian-Albrechts-Universität zu Kiel Medizinische Fakultat, Kiel, Germany
| | - Frederic Meyer
- Institute of Sport Science, University of Lausanne, Lausanne, Switzerland
| | - Christophe Hautier
- Inter-University Laboratory of Human Movement Biology (EA 7424), University Claude Bernard Lyon 1, Lyon, France
| | - Baptiste Morel
- Laboratory "Movement, Interactions, Performance" (EA 4334), Le Mans University, Le Mans, France.,Inter-University Laboratory of Human Movement Biology (EA 7424), Savoie Mont Blanc University, Chambéry, France
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Gross M, Lüthy F. Anaerobic Power Assessment in Athletes: Are Cycling and Vertical Jump Tests Interchangeable? Sports (Basel) 2020; 8:sports8050060. [PMID: 32397456 PMCID: PMC7281183 DOI: 10.3390/sports8050060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/29/2020] [Accepted: 05/06/2020] [Indexed: 01/09/2023] Open
Abstract
Regularly assessing anaerobic power is important for athletes from sports with an explosive strength component. Understanding the differences and overlap between different assessment methods might help coaches or smaller-scale testing facilities maximize financial and temporal resources. Therefore, this study investigated the degree to which cycling sprint and vertical jump tests are interchangeable for determining peak mechanical leg power output in strength-trained athletes. Professional skiers (n = 19) performed unloaded squat jumps (SJ) and other jump forms on a force plate and a six-second cycling sprint (6sCS) test on an ergometer on six occasions over two years. Along with cross-sectional correlations between cycling and jumping power, correlations between longitudinal percent changes and agreement between magnitude-based inferences about individual changes were assessed. Among the tested jump forms, SJ reflected 6sCS best. However, despite extremely large cross-sectional correlation coefficients (0.92) between 6sCS and SJ, and moderate (Pearson’s r = 0.32 for 6sCS with SJ over one-year time spans) to large (r = 0.68 over shorter time spans) correlation coefficients on percent changes, magnitude-based inferences agreed in only around 50% of cases. Thus, for making qualitative assessments about the development of anaerobic power over time in athletes, cycling sprint and squat jump tests are not interchangeable. Rather, we recommend employing the test form that best reflects athletes’ strength and conditioning training.
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Alhammoud M, Oksa J, Morel B, Hansen C, Chastan D, Racinais S. Thermoregulation and shivering responses in elite alpine skiers. Eur J Sport Sci 2020; 21:400-411. [DOI: 10.1080/17461391.2020.1754470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Marine Alhammoud
- French Ski Federation, Annecy, France
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
| | - Juha Oksa
- Workability and working Careers, Finnish Institute of Occupational Health, Oulu, Finland
| | - Baptiste Morel
- Inter-University Laboratory of Human Movement Biology (EA 7424), Savoie Mont-Blanc University, Chambéry, France
| | - Clint Hansen
- Department of Neurology, Christian-Albrechts-Universitat zu Kiel Medizinische Fakultat, Kiel, Germany
| | | | - Sebastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
- Laboratory Sport, Expertise and Performance, French Institute of Sport (INSEP), Paris, France
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