The present study investigated the relationship between self-efficacy, flow, positive- and negative affect, worry and ski jumping performance, as well as the degree of influence these psychological ...factors have on ski jumping performance in specific competitions and overall World Cup ranking. World Cup ski jumpers (
= 40) responded to four questionnaires in the middle of the World Cup season, reporting their subjective experience during a competitive setting over a period of three consecutive days. Social Cognitive Theory (SCT) and Flow Theory was used as main conceptual frameworks. Self-efficacy was moderately related to ski jumping performance, both overall World Cup ranking (
= -0.37) and the results from the first out of three individual ski flying competitions (
= -0.36) and explained approximately 14% of the variance in the overall World Cup. Flow was moderately related to ski jumping performance, both overall World Cup ranking (Flow-Focus) (
= -0.34), and individual ski flying results from the first competition (Flow-Arousal) (
= -0.36). The Flow-Arousal explained approximately 13% of the variance in ski flying results. Worry was highly related to ski jumping performance in the second (
= 0.60) and third (
= 0.52) competition, indicating that approximately 36 and 27% of the variance in ski flying results could be accounted for by levels of worry, respectively. Negative affect was moderately related to ski flying performance (
= 0.34). These results show that psychological factors that regulate emotional states may be of importance for World Cup ski jumping performance, and that appropriate coping strategies, constructive mindset and motivation, appears to be essential in this regard. To our knowledge, this is the first study on the relationship between these psychological factors and ski jumping performance among World Cup athletes. The study adds important information about some of the dynamic features of emotional and psychological mechanisms involved during elite ski jumping performance.
In recent years, anterior cruciate ligament (ACL) injuries have been frequently observed in ski jumping. However, available data in this discipline are very scarce. Therefore, the purpose of this ...study was to investigate whether an ACL injury in elite-level ski jumping limits the performance level after ACL reconstruction (ACLR).
Both male and female elite-level ski jumpers from five national A-teams who suffered an ACL injury were identified retrospectively by searching available media reports and Fédération Internationale de Ski (FIS) database. World Cup (WC) results and time-out-of-competition before ACL injury and after ACLR were compared. Only athletes who suffered the injury during or after the 2009-2010 season and who participated in at least one WC competition before the injury were included in this study. The level of athletes' performance from two full seasons before until three seasons after the injury was compared.
Eighteen elite-level ski jumpers (11 males/seven females) were eligible for the study. All male and four female athletes returned to professional competition after ACLR. One female athlete ended her career due to prolonged recovery and two have not yet recovered due to a recent injury. The mean return-to-competition (RTC) time was 14.6 months in males and 13.5 months in females. The mean WC placement decreased after the ACL injury: two seasons before injury the mean position was 17.9 ± 11.0 (n = 12), one season before it was 22.4 ± 12.8 (n = 15). After recovery, the mean placement in seasons 1-3 was: 26.4 ± 8.9 (n = 7), 25.7 ± 10.3 (n = 13), 33.6 ± 12.2 (n = 10) (p = 0.008). Among the athletes returning to competition, only six males and three females reached their preinjury level and only one male and one female (compared to seven males and three females preinjury) reached an individual top-3 placement after ACLR, accounting for less than 10% of podiums compared to preinjury.
Only 60% of the professional ski jumpers reached the preinjury level and less than 15% reached a top-3 placement after the ACL injury. These results support the fact that ACL tear during a ski jumping career may be a significant factor limiting high-level performance. In terms of clinical relevance, the findings implicate the need to analyse the reasons of these very low rates of return to elite-level performance, to analyse ACL injury and RTC rates at lower levels of performance and to develop specific prevention strategies in order to reduce the number of ACL injuries in this sport.
Level IV.
Nordic ski athletes are at increased risk of developing hip pain and dysfunction secondary to femoroacetabular impingement syndrome (FAIS), but it is unclear whether hip symptomatology differs ...between ski jumping (SJ) and Nordic combined (NC) athletes. The purpose of this study was to compare patient-reported hip pain and dysfunction between elite Nordic ski athletes participating in SJ versus NC.
A cross-sectional study was conducted involving SJ and NC athletes who competed at the international and U.S. national levels during the 2021–2022 season. Subjects were excluded if they had hip surgery within two years prior to enrollment. Subjects were asked to undergo diagnostic workups for FAIS, including physical examination and plain radiographic imaging. Subjects were asked to complete a survey that collected information on athletic and training history and to complete the hip disability and osteoarthritis outcome score (HOOS). Demographics, athletic/training history, and HOOS sub-scores were compared between the SJ and NC groups using the Student's t-test, Wilcoxon rank-sum test, or Fisher's exact test, as appropriate. p-values < 0.05 were considered significant.
Twenty-four athletes (13 SJ, 11 NC) were included in the study. There were no statistically significant differences in age, sex, BMI, or age of menarche between the two groups (all p > 0.05). There were also no statistically significant differences in the number of prior sports participated in, total hours of participation in prior sports, or total hours of training in Nordic specialization (all p > 0.05). Among the 18 athletes who underwent physical examination (9 SJ, 9 NC), there were no statistically significant inter-group differences in hip range of motion or incidence of positive impingement tests (all p > 0.05). Among the 19 athletes who underwent imaging (9 SJ, 10 NC), there were no statistically significant inter-group differences in the incidence of cam or pincer morphology in at least one hip (all p > 0.05). SJ athletes had statistically significantly worse HOOS sub-scores for hip symptoms and stiffness, hip function in sports/recreational activities, and hip-related quality of life compared to NC athletes (all p < 0.05).
Elite SJ athletes have worse self-reported hip function compared to elite NC athletes, despite comparable demographics, athletic history, and duration of ski training.
IV.
Several studies have suggested re-evaluation of the wind compensation system (WCS) of the International Ski Federation (FIS). It was introduced in 2009, and since then, the system has been modified ...considerably, but major shortcomings have still remained. The present study compared the effect of tail/head wind on two reference jumps with different aerodynamic properties (Cd and Cl) during the flight phase. Jump distance and total tangential wind speed data of world cup competitions of the season 2020/2021 were used to analyse the FIS WCS and to offer basic information of wind effects. The correlation between the total tangential wind speed and the jump distance varied strongly among the analysed jumping rounds and showed a big variation in the effect of FIS WCS. According to the computer simulation, a steady head/tail wind during the entire flight phase did not show big difference in jump distance between the jumps with different aerodynamic properties. However, wind had a “reverse” effect on the jumps: when applied to the early flight phase, tail wind increased, and head wind decreased the jumping distance. It seems that the favourable wind conditions at the early flight phase may result in an unfair advantage-disadvantage when the current FIS WCS is used. Therefore, based on the present results, the FIS WCS needs to be further discussed and quality of jumpers’ aerodynamic properties re-examined.
The purpose of this investigation was to compare how key variables of the steady glide phase relate to performance in the two hill sizes used in World Cup and Olympic competitions, i.e, normal and ...large hills. In this study, 38 and 33 jumps of elite ski jumpers were measured with a differential global navigation satellite system (dGNSS) on a normal (HS106) and large hill (HS140), respectively. For the steady glide phase, the average aerodynamic forces, lift-to-drag-ratio (LD-ratio), vertical and horizontal acceleration and velocity were measured and related to the jump distance as a performance outcome. The aerial time difference between the two hill sizes was 1.1s, explained by the time spent in the steady glide phase. The results for HS106 were in line with the assumptions in recent literature, which propose that the performance is largely determined by the take-off and glide preparation. Hence for normal hills, skiers should aim to reduce vertical acceleration through high aerodynamic forces during the glide phase. Also, no correlation was observed between the LD-ratio and jump length. The data from the large hill indicate that the performance during the steady glide is very important for performance; hence clear differences were found compared to the normal hill. On a large hill, the aim should be to minimize the horizontal deceleration by reducing the aerodynamic drag. A high LD-ratio was correlated to jump length for HS140 and seen to be one of the most important performance factors.
The stable flight posture that affects sports performance during flight is usually formed by the multiple angles of the athlete-ski posture. At present, research on the flight phase is mainly based ...on the single-factor impact analysis based on computational fluid dynamics simulation technology, but studies on the multi-factor coupling relationship of two or more factors is less. This study aims to determine the best optimal-level combination based on the simulation model of this work through comprehensive evaluation from the optimisation perspective of multi-factor coupling. Here, a refined model of the athlete-ski system with the characteristics of ski jumping was established. Reynolds time-averaged method was used for the simulation. A three-factor and five-level simulation test was conducted on the relative inclination between skis, the angle between the body and the ski and the ski V-angle through orthogonal experiment design. Our results show that the optimal-level combination of the relative inclination between skis of 120°, the angle between the body and the ski of 20°, and the ski V-angle of 30° is relatively best in terms of aerodynamic characteristics. Simulation results were similar to the results of the winter field data from video analysis, and the results were effective.
This study investigated the explanatory power of a sensor fusion of two complementary methods to explain performance and its underlying mechanisms in ski jumping. A differential Global Navigation ...Satellite System (dGNSS) and a markerless video-based pose estimation system (PosEst) were used to measure the kinematics and kinetics from the start of the in-run to the landing. The study had two aims; firstly, the agreement between the two methods was assessed using 16 jumps by athletes of national level from 5 m before the take-off to 20 m after, where the methods had spatial overlap. The comparison revealed a good agreement from 5 m after the take-off, within the uncertainty of the dGNSS (±0.05m). The second part of the study served as a proof of concept of the sensor fusion application, by showcasing the type of performance analysis the systems allows. Two ski jumps by the same ski jumper, with comparable external conditions, were chosen for the case study. The dGNSS was used to analyse the in-run and flight phase, while the PosEst system was used to analyse the take-off and the early flight phase. The proof-of-concept study showed that the methods are suitable to track the kinematic and kinetic characteristics that determine performance in ski jumping and their usability in both research and practice.
The aim of this paper is to propose a hybrid framework that combines a data-driven pose estimation with model-based force calculation in order to predict the ski jumping force from a recorded motion ...video. A skeletal model consisting of five joints (ear, hip, knee, ankle, and toe) and four rigid segments (head/arm/trunk or HAT, thigh, shank, and foot) connecting each joint is developed. The joint forces are calculated from the dynamic equilibrium equations, which requires the time history of joint coordinates. They are estimated from a recorded motion video using a deep neural network for pose estimation trained with human motion data. Joint coordinates can be obtained by the proposed deep neural network directly from images of jumping motion without using any markers. The validity and usefulness of the proposed method are confirmed in lab experiments. Further, our method is practically applicable to the study in a real competition environment because it is not required to attach any sensor or marker to athletes.
Highlights
A method to predict the ski jumping force from a recorded motion video is proposed.
It combines a data-driven pose estimation with a model-based force calculation.
The proposed method does not require any markers and sensors to be attached to athletes.
In a laboratory environment, the relative error in the maximum jumping force is less than 7%.
The method can be easily applied to a field study in a real competition environment.
The purpose of this study was to find a generic method to determine the aerial phase of ski jumping in which the athlete is in a steady gliding condition, commonly known as the 'stable flight' phase. ...The aerial phase of ski jumping was investigated from a physical point mass, rather than an athlete-action-centered perspective. An extensive data collection using a differential Global Navigation Satellite System (dGNSS) was carried out in four different hill sizes. A total of 93 jumps performed by 19 athletes of performance level, ranging from junior to World Cup, were measured. Based on our analysis, we propose a generic algorithm that identifies the stable flight based on steady glide aerodynamic conditions, independent of hill size and the performance level of the athletes. The steady gliding is defined as the condition in which the rate-of-change in the lift-to-drag-ratio (LD-ratio) varies within a narrow band-width described by a threshold τ. For this study using dGNSS, τ amounted to 0.01s
, regardless of hill size and performance level. While the absolute value of τ may vary when measuring with other sensors, we argue that the methodology and algorithm proposed to find the start and end of a steady glide (stable flight) could be used in future studies as a generic definition and help clarify the communication of results and enable more precise comparisons between studies.
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