Alpine Ski Racing Research Articles

Bioimpedance Vector Analysis-Derived Body Composition Influences Strength and Power in Alpine Skiers

ABSTRACT Purpose: Alpine ski racing is a complex sport where no single factor can exclusively account for performance. We assessed body composition, using bioelectrical impedance vector analysis (BIVA), and our purpose was to study its influence on the strength and power profile of young alpine skiers. Methods: Anthropometric measurements and advanced BIVA parameters were recorded on eighteen alpine ski racers (6 females/12 males; 17.0 ± 1.3 years; 172.2 ± 9.3 cm; 68.5 ± 9.8 kg). Dynamic force and power were assessed using countermovement jumps (CMJ), while maximal isometric strength was evaluated for hip flexion-extension and abduction-adduction movements. Stepwise regression models examined the relationship between BIVA-derived parameters and strength/power variables. Results: Body cellular mass (BCM) positively related to jump height (p = .021, R 2 = 74%), jump momentum (p < .001, R 2 = 89%), reactive strength index modified (p = .026, R 2 = 75%) and peak concentric power (p < .001, R 2 = 82%), while intracellular water (ICW) related to peak eccentric (p < .001, R 2 = 76%) and concentric force (p < .001, R 2 = 77%) as well as to concentric rate of force development together with the phase angle (PhA) (p = .008, R2 = 79% and R2 = 0.015). Regarding isometric assessment, ICW was a significant predictor for all four movement directions, and PhA contributed to hip adduction strength. Conclusions: Body composition, particularly BCM and ICW, significantly predict force- and power-related factors in young alpine skiers.

A graph-based approach can improve keypoint detection of complex poses: a proof-of-concept on injury occurrences in alpine ski racing

For most applications, 2D keypoint detection works well and offers a simple and fast tool to analyse human movements. However, there remain many situations where even the best state-of-the-art algorithms reach their limits and fail to detect human keypoints correctly. Such situations may occur especially when individual body parts are occluded, twisted, or when the whole person is flipped. Especially when analysing injuries in alpine ski racing, such twisted and rotated body positions occur frequently. To improve the detection of keypoints for this application, we developed a novel method that refines keypoint estimates by rotating the input videos. We select the best rotation for every frame with a graph-based global solver. Thereby, we improve keypoint detection of an arbitrary pose estimation algorithm, in particular for ‘hard’ keypoints. In the current proof-of-concept study, we show that our approach outperforms standard keypoint detection results in all categories and in all metrics, in injury-related out-of-balance and fall situations by a large margin as well as previous methods, in performance and robustness. The Injury Ski II dataset was made publicly available, aiming to facilitate the investigation of sports accidents based on computer vision in the future.

On the relationship between flexibility and jump performance across age and sex: A 15-season retrospective longitudinal study on 229 alpine ski racers

Alpine skiing performance depends on several qualities, including lower limb strength, power production and flexibility. However, how these physical skills, as well as their relationship, differ between sexes and evolve in growing skiing athletes is still unclear. We analysed sit-and-reach (SR) and three jump test (height and peak power) scores of over 200 alpine ski racers collected across 15 sports seasons. We stratified data among sex and age categories to assess differences and to interpret the relationships between flexibility and jump performance. The mixed models showed a significant age category and sex effect ( p &lt; 0.001) for all the flexibility and jump performance scores, with males having higher jump scores but lower SR scores than females, and all performance scores increasing significantly through the age categories. The regressions between SR and the jump scores performed on the whole database were positively significant for the three jump variations ( p &lt; 0.001, R2 ranging from 8.9% to 15.9%), while when the relationship was reanalysed independently in each age–sex group, only some were significant. Both age and sex influenced the performance in the investigated lower limb power and flexibility qualities, along with their relationship. The presented results suggest that lower limb power and flexibility should be longitudinally assessed, as well as their relationship, for training and testing purposes, considering the sex and growth-related modifications.

We know a lot about little and little about a lot: A contextualized scoping review on injury prevention in alpine ski racing.

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. 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. 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. 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.

Concomitant Injuries Associated With ACL Rupture in Elite Professional Alpine Ski Racers and Soccer Players: A Comparative Study With Propensity Score Matching Analysis.

For elite professional soccer players and alpine skiers, injuries associated with anterior cruciate ligament (ACL) rupture, such as meniscal, cartilage, or collateral ligament lesions, could result in a delayed return to sport compared with isolated ACL injury. The purpose of the study was to provide a detailed description of associated injuries at the time of primary ACL reconstruction in elite soccer players and alpine skiers. It was hypothesized that soccer players and skiers would present different typical injury patterns due to different injury mechanisms. Cohort study; Level of evidence, 3. Surgical reports and arthroscopic images of elite professional soccer players and alpine skiers who underwent primary ACL reconstruction at a single institution between January 2010 and June 2022 were analyzed retrospectively. The presence and location of multiligamentous injury, meniscal tears, and chondral lesions were compared between the athlete groups. A propensity score matching analysis with 1:1 ratio was performed between skiers and soccer players to limit the effect of selection bias. Included were ACL reconstruction data representative of 37 soccer players and 44 alpine skiers. Meniscal pathology was found in 32 (86%) soccer players and 30 (68%) skiers. Chondral injuries were reported in 11 (30%) soccer players and 15 (34%) skiers. Results of the propensity score matching analysis in 15 pairs of soccer players and skiers indicated that soccer players had a significantly higher rate of medial meniscal injuries (73% vs 27%; P = .03) and lateral posterior root tears (33% vs 0%; P = .04) compared with skiers. A higher prevalence of combined chondral and meniscal injuries versus isolated ACL injuries was observed in both groups of athletes. Professional soccer players were characterized by higher prevalence of medial meniscal tears and lateral posterior root lesions compared with professional alpine skiers.

Tracing burnout during adolescence to past sports experiences: a retrospective analysis of sport-specific antecedents among alpine ski racers

IntroductionPrevious theoretical frameworks focusing on burnout have identified numerous antecedents and psychosocial risk factors; however, the influence of early sport-specific experiences on burnout in developmental athlete populations remains less understood. ObjectivesWe explored the associations between burnout and prior sports engagement (ie, milestones, practice time, performance, injury history) in a sample of subelite academy alpine ski racers in the United States (N = 169, M age = 15.82 ± 1.80). MethodsParticipants completed retrospective practice history profiles (milestones, practice time, injury), while their respective performance data were collected using an online national ranking registry. Simple and mixed-effect regressions were implemented to assess the associations between these measures and subscales of the Athlete Burnout Questionnaire. ResultsThe results indicated that greater participation in the coach-led group and individual practice during adolescence mitigated burnout responses (ie, greater sense of accomplishment, less sport devaluation), whereas more play earlier in development was associated with greater devaluation. Furthermore, poorer performance and more injury incidences were associated with increased burnout (ie, reduced sense of accomplishment). ConclusionsThe structure of training and past experiences during early career years appear to influence burnout among alpine ski racing during their adolescent years, the implications of which are discussed in relation to sport developmental pipelines.

Deep learning-based 2D keypoint detection in alpine ski racing – A performance analysis of state-of-the-art algorithms applied to regular skiing and injury situations

ObjectivesIn this study, we examined the practicability of deep learning-based 2D keypoint detection applied to regular skiing and injury situations (i.e., out-of-balance situations and fall situations) on an alpine ski racing track. MethodsWe therefore created a regular skiing- and injury situation-specific dataset (hereinafter called "Injury Ski Dataset"), on which the state-of-the-art keypoint detection algorithms OpenPose, Mask-R-CNN, AlphaPose and DCPose were compared. The performance of each keypoint detector was evaluated by calculating the mean per joint position error (MPJPE) and the percentage of correct keypoints (PCK). Failure cases and common error patterns were further investigated by a visual analysis. ResultsWe observed the best results for regular skiing, with 81%–92% of all keypoints detected correctly at an MPJPE of 9 (2) to 14 (3) pixels. In injury situations, self-occlusions and rare poses became more likely, similar to occlusions due to snow spray and motion blur. As a result, the performance in out-of-balance situations decreased to 68%–80% (PCK), while in fall situations, only 35%–54% of all keypoints were detected correctly, with mean errors of 26–36 pixels. Among all algorithms, AlphaPose was the most robust and achieved the best results. ConclusionsPCK and MPJPE for regular skiing were in the range of manual annotation errors and can be considered low enough for further biomechanical analysis. For fall situations, keypoint detection should be further improved. Regarding the development of a deep learning tool for injury analysis in alpine skiing in the future, we propose to fine-tune a well-performing keypoint detector, such as AlphaPose, on a ski- and injury-specific dataset, such as ours.

Is there a contextual interference effect for sub-elite alpine ski racers learning complex skills?

Scientific understanding of the contextual interference effect stems mainly from studies on unskilled participants learning artificial laboratory tasks. Although one goal of such studies is to extrapolate the findings to include real-world learning situations such as sports, this generalization is not straightforward. This study tested the contextual interference effect with 66 sub-elite, competitive alpine ski racers who learned a new movement pattern−the pumping technique to increase velocity in slalom−by practicing this skill in three different slalom courses over a 3-day training period. The interleaved group practiced all three courses each day in a semi-random order. In contrast, the blocked group practiced only one course each day, which was randomized and counterbalanced across the participants in this group. A retention test was delivered 72 h after the last practice day. In contrast to our hypothesis, the interleaved group did not display significantly better retention than the blocked group. The interleaved group’s performance was also not significantly attenuated during skill learning compared to the blocked group. Our results underscore the importance of conducting motor learning experiments in natural environments to understand the conditions that facilitate learning beyond the laboratory environment.

Physical therapy recommendations for injury prevention in alpine skiing

Introduction: Alpine skiers face high speeds, significant forces, natural and unnatural obstacles, and various environmental conditions on the slopes. Thus, they are highly exposed to certain injuries, amongst which the most common are those to the knee followed by injuries to the spine, shins, head, as well as arm and thumb injuries. Purpose: The purpose was to systematically review the scientific literature on injuries, risk factors, and prevention in competitive alpine skiing and to provide recommendations for injury prevention in the field of physical preparation, kinesiotherapy, and/or specific exercises, and to determine which exercise program would be most appropriate for an alpine ski racer. Methods: PubMed, Web of Science, and COBISS databases were used with PRISMA method to review the physical therapy recommendations for injury prevention in alpine skiing. Results: 10 studies were included in the final systematic review. We have not found any evidence-based prevention programs that are not older than 10 years on the topic of physical preparation for alpine ski racers. We found that most often, the literature describes prevention in terms of equipment, course preparation, course safety awareness, and the experience of the skier. Conclusions: The recommendation for the most efficient prevention according to the current literature is to follow the above preventive measures in combination with appropriate physical preparation, where we recommend relying on research evidence in other (non-contact) sports that have similar injury mechanisms as alpine ski racing.

"Being" an Older Adult Skier: The Phenomenology of Masters Alpine Ski Racers.

This research examined the lived experience of older adult Alpine skiers in their continued participation in competitive ski racing. The aim was to gain an understanding of the meaning of the experiences for older adults as they continued to compete in Alpine ski racing. Masters skiers between the ages of 69 and 82 years participated in individual interviews. Data collection and analysis were iterative processes informed by phenomenological methods and visual mind mapping. The overarching theme identified in participants' accounts was the significance of the identity of "Being" a Ski Racer. Supporting subthemes were Enjoying the Feeling of Ski Racing, Adapting in the Sport, and Skiing as a Lifestyle. These insights offer the opportunity to encourage and support the holistic experiences of older adults who maintain their athletic identity as they age. This research highlights how inclusion of older adults' stories may foster critical reflexivity and challenge assumptions about aging.

Attenuated Lower Limb Stretch-Shorten-Cycle Capacity in ACL Injured vs. Non-Injured Female Alpine Ski Racers: Not Just a Matter of Between-Limb Asymmetry.

A retrospective analysis of routine countermovement jump (CMJ) testing, a coupled eccentric-concentric (stretch-shorten-cycle: SSC) movement, was performed in female elite alpine skiers with anterior cruciate ligament (ACL) reconstruction (ACLR) and without ACLR. A total of 567 tests obtained from the daily training environment were analyzed in 41 elite female athletes (non-injured control: n = 30, ACLR: n = 17), including n = 6 athletes with pre-injury data, between 16 and 32 years of age from alpine ski racing (n = 32) and skier cross (n = 9). Bilateral CMJ testing was conducted on a dual force plate system, and the limb-specific vertical ground reaction force (Fz) was analyzed to obtain the net eccentric deceleration impulse (Ecc), lower limb stiffness (Stiff), maximal vertical jump height (JH), peak external mechanical power (PP) exerted on the body center of mass (BCM), modified-reactive-strength-index (RSImod), and the loss in BCM velocity during the final phase of the takeoff Δ(Vmax–Vtakeoff). Eccentric and concentric phase-specific between-limb asymmetry indexes (AIs) were also calculated. Additive mixed effects models (AMMs) were used to compare the age-dependent and post-injury time course change between groups. The mean values for non-injured controls >25 years of age were used as a comparative benchmark for recovery given the absence of pre-injury data. Net eccentric deceleration impulse increased and Δ(Vmax–Vtakeoff) decreased with age for the non-injured control group (p < 0.001) while between-limb AI (mean ± SD) fell between 1 ± 5% for the concentric phase and 3 ± 7% for the eccentric deceleration phase. Between-limb asymmetry became smaller in ACLR skiers with time-from-surgery to reach non-injured control values by 2 years, but SSC function, such as JH and PP, remained depressed up to 5 years post-surgery (p < 0.01), indicating impairments in SSC function. This highlights the importance of evaluating SSC performance capacity alongside vertical jump force-time asymmetries in female ACLR alpine skiers.

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

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 &lt;2.5%, they provide a valuable tool for analysis of skiing performance.

In-Competition Severe Injury Events in Elite Alpine Ski Racing from 1997 to 2020: The Case of the Austrian Ski Team

BackgroundTo increase safety in elite alpine ski racing Injury Surveillance Systems were implemented and preventive measures introduced. However, studies analysing the change in athletes’ injury risk by controlling for their exposure are still scarce.ObjectivesThis study aimed to describe and analyse the risk of in-competition severe injury events (SIEcomp) in elite alpine ski racing.MethodsData recorded in the Austrian Ski Federation’s Injury Surveillance System were used to analyse the SIEcomp incidence. Information on athletes’ competition exposure was obtained from the official website of the International Ski Federation. In 23 seasons, 2333 skier seasons were recorded for the Austrian Ski Team. Within a total of 114,531 runs 169 SIEcomp occurred. Generalised Estimating Equation for Poisson Regressions were applied.ResultsThe SIEcomp incidence per 1000 runs was 1.48 [95% confidence interval (CI) 1.26–1.73] for elite alpine ski racers and 2.21 (95% CI 1.79–2.75) for the subgroup of World Cup racers. A significant sex difference was detected for the subgroup of junior racers with a higher risk for female athletes [risk ratio (RR): 2.97, 95% CI 1.46–6.05]. Between the seasons of 1997 and 2020, the seasonal SIEcomp incidence increased by a factor of 2.67 for elite alpine ski racers and 3.53 for World Cup racers. Downhill (2.75, 95% CI 2.18–3.47) had the highest SIEcomp incidence, followed by super-G (1.94, 95% CI 1.30–2.88), giant slalom (1.40, 95% CI 1.06–1.85), and slalom (0.64, 95% CI 0.43–0.96).ConclusionAlthough many preventive measures have been implemented in elite alpine ski racing, the risk of SIEcomp has increased over the last two decades.

The Relationship between Field Test and Laboratory Test for Junior Alpine Ski Racers

The Relationship between Field Test and Laboratory Test for Junior Alpine Ski Racers

Validity of the AdMos, Advanced Sport Instruments, GNSS Sensor for Use in Alpine Skiing

The AdMos receiver from Advanced Sport Instruments is a global navigation satellite system (GNSS) frequently used in alpine ski racing, with users from national and professional teams. Therefore, a validation was conducted for use of the AdMos in alpine skiing, using data from both recreational and competitive skiers. Athletes skied a total of 60 km in different measurement and skiing conditions, while carrying both an AdMos and a differential GNSS, which was used as the gold standard. From the GNSS position data, speed, acceleration, turn radius, trajectory incline and impulse were calculated as instantaneous and turn average measures for both GNSS systems and errors between the systems were calculated. The median and interquartile range (IQR) for the instantaneous errors were below 3.5 (3.5) m for horizontal plane position and below 7.0 (4.3) m for the 3D position. The median and IQR for instantaneous errors and turn average errors, respectively, were below 0.04 (0.24)/0.04 (0.16) m/s for speed, below 0.23 (1.06)/0.35 (0.63) m/s2 for acceleration, below 0.47 (5.65)/0.73 (5.3) m for turn radius, and below 0.043 (1.96)/0.42 (1.42) degrees for trajectory incline. The median and IQR for turn average impulse were 0.025 (0.099) BWs. The position error changed gradually and randomly over time, with low noise levels causing smooth trajectories of similar shape but spatially shifted from the true trajectory that allowed the position–time derivation of the performance parameters, and detection of turns with 3% median and 5% IQR error. The accuracy assessment revealed that (1) the error levels were comparable to other consumer-grade standalone GNSS units designed for sport; (2) the trajectories closely resembled the true trajectories but with a random shift that changed over time and had a low noise level; (3) there was a very low instantaneous speed error that may allow the detection of many performance aspects of skiing and other sports; and (4) there were larger instantaneous errors for the remaining performance parameters, which decreased substantially when averaged over a turn.

Perceptions of experts on key injury risk factors in alpine ski racing as a function of stakeholder role and associated level of competition

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...

Experience and Management of Fear in Men's World Cup Alpine Ski Racing.

Alpine ski racers, specifically in the discipline of downhill, may experience fear competing in such a high-risk environment. The purpose of this study was to explore Canadian national team men's experience and management of fear in World Cup alpine ski racing. This study uses an interpretive phenomenological analysis, conducted with five male members of the Canadian national ski team. Three themes emerged: contextual influences, preparation and process, and risk vs. reward. The findings indicate one's experience and management of fear may be influenced by contextual factors (e.g., weather, course profile) and confidence, and that confidence is influenced by the same situational factors that influence fear as well as athlete preparation. There currently exists a discrepancy between the athletes' approaches to training and racing, making it difficult to master fear management strategies. As a result of the discrepancy created between training and racing, there are several implications for how the national team environment and training is structured, and we present recommendations for how these findings can be applied to training.

The Influence of Ski Type on Muscle Activity, Performance, and Self-Efficacy in Young Alpine Ski Racers

The Influence of Ski Type on Muscle Activity, Performance, and Self-Efficacy in Young Alpine Ski Racers

The relative age effect is associated with career sport engagement in alpine ski racers attending training centers

ObjectivesThe relative age effect (RAE), a phenomenon where relatively older athletes in a selection year are overrepresented, has been evidenced across different sports and age-levels. No published reports have assessed if the RAE influences practice time for relatively younger athletes, which could contribute to sport success. In this study, we compared patterns for performance and sport engagement between earlier-born and later-born adolescent alpine ski racers from Austria (AUT) and the United States (US). Design and methodsWe assessed birth quarter distribution and performance trends using a performance (FIS) database (US: N = 2172; AUT: N = 516), and sport engagement through administering a practice history questionnaire to athletes attending ski academies/boarding schools (US: N = 169; AUT: N = 209). ResultsChi-square analyses revealed an underrepresentation of athletes born later in both samples. Mixed regressions only showed performance improvements for later-born US ski racers. Relatively younger athletes in Austria engaged in more individual and group practice over time, while no clear practice patterns emerged for US ski racers. ConclusionsResults suggest that later-born ski racers in Austria need to practice more to bridge skill/performance gaps with their relatively older peers. Additionally, later-born ski racers who do not put in extra practice may be deselected. Practice time may be less pivotal for relatively younger ski racers in the US due to less strict talent filtration systems. Coaches can ameliorate the RAE by dedicating more attention during practice towards developing relatively younger athletes who are transiently overshadowed by older, higher-performing athletes.

Acute on-snow severe injury events in elite alpine ski racing from 1997 to 2019: the Injury Surveillance System of the Austrian Ski Federation

ObjectivesThe study aimed to (1) determine the incidence and gender-specific risk ratio of acute on-snow severe injury events (SIE) in elite alpine ski racing, (2) examine the development of SIE...