Search Results (125)

Tibial torsion significantly influences knee biomechanics, yet its interaction with ACL reconstruction history in elite alpine skiers remains under-investigated. In this cross-sectional observational study, we analyzed 20 elite alpine skiers (7 ACL-reconstructed, 13 non-injured) using a markerless motion capture system during dynamic tasks (Squat, Single-Leg Squat, Lunge). Static tibial torsion was assessed via the Transmalleolar Axis and Thigh–Foot Angle. The results revealed a critical divergence in biomechanical strategies based on tibial alignment (p < 0.05). Skiers with rotational deformity adopted a pattern we describe as a “Stiffness Strategy”, characterized by suppressed knee valgus and hip rotation, but relied on excessive ankle dorsiflexion (39.5°)—a compensatory mechanism that may become limited when constrained by rigid ski boots. In contrast, ACL-reconstructed skiers with normal alignment exhibited what we term an “Instability Strategy”, showing dynamic valgus collapse and persistent asymmetry. These findings suggest that “one-size-fits-all” rehabilitation may be insufficient. We propose that injury prevention protocols may benefit from incorporating anatomical screening, focusing on decoupling mobility for skiers with tibial torsion and enhancing dynamic stability for those with normal alignment. Full article

Capturing kinematic data in outdoor sports is challenging, as motions span large capture volumes and occur under difficult environmental conditions. Video-based approaches, particularly with pan–tilt–zoom cameras, offer a practical solution, but the extensive manual post-processing required limits their use to short sequences and few athletes. This study presents a motion capture pipeline that automates the detection of both reference points and sport-specific keypoints to overcome this limitation. The field test employed eight cameras covering a $250\times 80\times 30 \mathrm{m}$ capture volume with nearly 300 reference points. Ten state-certified ski instructors performed eight standardized maneuvers. Reference points were localized through a hybrid approach combining YOLO object detection and ArUco marker identification. AlphaPose was fine-tuned on a new manually annotated dataset to detect skier-specific keypoints (e.g., skis, poles) alongside anatomical landmarks. Continuous frame-wise calibration and 3D reconstruction were performed using Direct Linear Transformation. Evaluation compared automated detections with manual annotations. Automated reference point detection achieved a mean localization error of $4.1$ pixels ($0.1\%$ of 4K width) and reduced 3D segment-length variation by $23\%$. The skier-specific keypoint model reached $98\%$ PCK, mAP of $0.97$, and an MPJPE of $10.3$ pixels while lowering 3D segment-length variation by $0.5 \mathrm{cm}$ compared to manual digitization and $0.6 \mathrm{cm}$ relative to a pretrained model. Replacing manual digitization with automated detection improves accuracy and facilitates kinematic data collection in large outdoor fields with many athletes and trials. The approach also enables the creation of sport-specific datasets valuable for biomechanical research and training next-generation 3D pose estimation models. Full article

Background: Alpine skiing imposes high biomechanical demands on the lower limbs, which are further amplified in individuals with transfemoral amputation due to prosthetic constraints. This study aimed to quantify three-dimensional knee flexion asymmetries during alpine skiing turns in transfemoral amputee skiers compared with non-disabled controls. Methods: Five unilateral transfemoral amputee skiers (intervention group) and five non-disabled ski instructors (control group) performed six left and six right turns on a skiing simulator under laboratory conditions. Knee flexion angles at the apex of each turn were analyzed using three-dimensional motion capture. Intra-individual differences between the prosthetic and intact limbs were assessed using paired comparisons, and inter-individual differences between groups were evaluated using independent statistical tests (p < 0.05), performed in IBM SPSS Statistics. Results: Intra-individual analysis revealed significant knee flexion asymmetries (p < 0.05) in almost all amputee participants at the apex of both left (mean difference = 7.74°, 95% CI: 3.38–12.09) and right turns (mean difference = 4.36°, 95% CI: 2.66–6.06). In the control group, asymmetries were smaller and reached significance only for the inside leg in both turns (mean difference = 4.02°, 95% CI: 2.51–5.54). Inter-individual comparisons demonstrated significant differences between the groups for both turning directions. During left turns (prosthetic limb on the inside), the largest difference was observed for the inside leg (26.9°, p < 0.001), while the smallest difference occurred for the outside leg (12.1°, p = 0.013). During right turns (prosthetic limb on the outside), the largest difference was found for the outside leg (19.0°, p < 0.001), with a smaller but still significant difference for the inside leg (14.0°, p < 0.001). Conclusions: Transfemoral amputee skiers exhibit a turning strategy that is qualitatively comparable to that of non-disabled skiers; however, it is characterized by a reduced knee flexion range of motion. These limitations appear to be primarily influenced by prosthesis mechanics and user-specific skill levels rather than by a fundamentally different movement strategy. Full article

Introduction: Anterior cruciate ligament (ACL) injuries are among the most severe and frequent injuries in alpine skiing, often occurring in non-contact situations during high-demand turns. Various instrumental techniques were used to assess susceptibility to anterior cruciate ligament (ACL) injuries in alpine ski racers and recreational skiers. This cross-sectional exploratory study aimed to identify key factors contributing to ACL injury susceptibility, comparing lab-based and on-snow tests. Materials and Methods: We examined nine elite ski racers and nine recreational skiers with strong athletic backgrounds. Skiing technique was analyzed using an instrumented insole system (CARV) to measure body position, pressure symmetry, and edge angle. Dynamic Q-angle symmetry during single-leg squats were assessed with an optical system (DynaKnee), while balance, strength, and agility were evaluated through ACL-specific lab tests (CoRehab). Group comparisons were performed using the nonparametric Mann–Whitney U test. Results: No significant differences were found between groups in ACL-specific lab tests, including balance, agility, and jump performance. However, ski racers exhibited 34.9% higher asymmetry in the Q-angle symmetry index during the one-leg squat. In contrast, ski technique differences were significant: ski racers achieved 16.3% higher Edge Similarity, 48% better Pressure Symmetry, and 5.8% better Fore-Aft Balance compared to recreational skiers. Conclusions: Despite similar general athletic abilities, elite skiers showed higher Q-angle asymmetry, which has been previously associated with ACL injury risk. However, their advanced skiing technique may partially mitigate the functional consequences of this asymmetry during on-snow tests. This suggests that refined skiing skills may influence functional performance in racing conditions, while pronounced one-sided dominance could indicate potential injury risk. Full article

Performance diagnostics in alpine skiing increasingly rely on integrated biomechanical and kinematic assessments to support technique optimization under real training conditions; however, many existing approaches address trajectory geometry or biomechanical variables separately, limiting their explanatory power. This study evaluates an integrated analysis framework combining OptiPath, an AI-assisted video-based trajectory analysis tool, with XSensDOT wearable inertial sensors to identify technical inefficiencies during giant slalom skiing. Thirty competitive youth athletes (n = 30; 14–16 years) performed controlled runs with predefined lateral offsets from the gates, enabling systematic examination of the relationship between spatial trajectory deviations, biomechanical execution, and performance outcomes. Skier trajectories were extracted using computer vision-based methods, while lower-limb kinematics, trunk motion, and tri-axial acceleration were recorded using inertial measurement units. Deviations from mathematically defined ideal trajectories were quantified through regression-based calibration and arc-based modeling. The results show that although OptiPath reliably detected trajectory variations, shorter skiing paths did not consistently produce faster run times. Instead, superior performance was associated with more efficient biomechanical execution, reflected by coordinated trunk–lower limb motion, controlled vertical loading, reduced lateral corrections, and higher forward acceleration, even when longer trajectories were followed. These findings indicate that trajectory geometry alone is insufficient to explain performance outcomes and support the integration of wearable biomechanics with trajectory modeling as a practical, low-cost, and field-deployable tool for alpine skiing performance diagnostics. Full article

The snowpack in the European Alps is declining due to global warming, which affects both the amount of seasonal snow and the timing of accumulation and melt. As the European Alps is the largest winter tourism destination in the world by revenue, this decline in natural snow poses an existential threat to the sector. Several smaller ski areas have closed permanently since 1980, and all Alpine regions face rising costs due to an increasing reliance on snowmaking. Professional winter sports are also affected, with several canceled events in recent years due to unsuitable snow conditions. In this study, we present the first remote sensing-based assessment of long-term snow reliability for winter tourism in the European Alps. Using snowline elevation (SLE) data derived from Landsat observations from 1985 to 2024, combined with OpenStreetMap ski infrastructure data and digital elevation models, we quantified the monthly snow coverage of ski area segments across 43 Alpine basins. Theil–Sen trends and Mann–Kendall significances were calculated for the full season and for three subseasons, with quality checks applied to guarantee sufficient data coverage. The results show predominantly negative trends across all seasons, with the strongest declines occurring in the late season. In this period, 97.8% of all downhill ski areas and 99.5% of the cross-country ski areas for which a trend was derived exhibited negative trends. For the full season, the corresponding shares were 94% for downhill ski areas and 99.2% for cross-country ski areas. In addition, areas located at the geographical edges of the European Alps showed more pronounced negative trends compared with the core regions. These findings align with previous studies on the subject and highlight the ongoing shortening of natural snow seasons and thus the increased challenges for the winter tourism sector in the Alps. Full article

Background/Objectives: Lower extremity injuries represent a major health concern in elite snowsport disciplines, where high mechanical loads, complex movement patterns, and demanding environmental conditions substantially increase injury risk. Understanding injury incidence and burden in this population is essential for developing sport- and sex-specific prevention strategies. This retrospective study determined lower extremity injury incidence and burden among elite snowsport athletes. Methods: Ninety-nine Turkish National Snowsport Teams Training Camp athletes (34 females; 65 males) consented to a review of their medical records for injury incidence. Overall, sex- and sport-specific injury incidence (number/10,000 h) and burden (weeks missing/10,000 h) were calculated. Results: Overall, medial tibial stress syndrome (MTSS) was the highest burden (9.5 ± 38.7), and ankle sprain (1.7 ± 0.4) was the highest-incident injury. However, injury incidence and burden patterns differed by sex and sport. Notably, medial tibial stress syndrome (MTSS) showed comparable incidence in female and male athletes but resulted in a substantial injury burden in both sexes, reflecting prolonged time-loss from training and competition and indicating a meaningful negative impact on athletic performance. Specifically, the highest-burden injury for women was anterior cruciate ligament (ACL) rupture (16.2 ± 64.5), and for men the most common injury was MTSS (9.7 ± 40.7). For cross-country skiers, MTSS had the highest burden and incidence. For all other sports, and across sexes, ankle sprain was the highest incidence injury—women (1.3 ± 3.0), men (2.0 ± 4.5), biathletes (2.3 ± 5.7), Alpine skiers (2.8 ± 4.5), ski jumpers (1.6 ± 3.1), and snowboarders (3.2 ± 4.7)—plus the highest-burden injury for biathletes (6.9 ± 14.3) and ski jumpers (6.0 ± 14.0). The highest burden injury for Alpine skiers was ACL damage (34.3 ± 87.2), and for snowboarders it was knee collateral ligament injury (27.8 ± 78.6). Moreover, patellar tendinitis, hamstring strains, calf strains, Achilles ruptures, anterior tibial pain, meniscus tears, and hip injuries were frequently observed in injury patterns. Conclusions: Ankle sprains were the most frequent lower extremity injury in elite snowsport athletes, whereas medial tibial stress syndrome (MTSS) and anterior cruciate ligament (ACL) injuries accounted for the greatest injury burden. Injury incidence and burden differed by sex and snowsport discipline. Full article

Before returning to sport (RTS) following lower extremity injury, competitive alpine skiers’ performance strength profiles should be verified. This study examined whether differences in maximal isometric (F_max) and explosive strength (P_max) exist between non-injured (n_INJ) and post-injured (p_INJ) elite skiers (n = 56) after RTS. It also explored whether F_max and P_max values recover differently over time and whether restoration rates differ between males and females. An explorative analysis was conducted to determine differences in back-squat F_max and P_max during squat (SJ) and countermovement jumps (CMJ) without and with additional load. Data were available from before injury and after athletes’ RTS for p_INJ or twice across a comparable time span for n_INJ. While differences between n_INJ and p_INJ after rehabilitation are not significant for Fmax, p_INJ generally display significantly lower Pmax (r = 0.34–0.40). Additionally, results suggest that F_max is restored first, followed by P_max without eccentric component (SJ), and that P_max (CMJ) with eccentric component is restored slowest. Further, p_INJ showed lower P_max in loaded jumps even before injury (p = 0.035–0.047, r = 0.36–0.39). Finally, females display generally lower P_max for a given F_max. Overall, these results contribute to improving rehabilitation and prevention. Full article

Background/Objectives: High-altitude hypoxia may affect ECG readings, but it is unclear whether the “live-low–train-high” approach prevents these changes in winter sports athletes. Methods: This cross-sectional study assessed cardiovascular parameters in 102 winter-sport athletes (mean age 20 ± 4 y; 57% women), divided by training altitude into a high-altitude (HA) group (2500–3300 m, n = 70; skiers/snowboarders) and a low-altitude (LA) group (738 m, n = 32; ice hockey/figure skaters). Mid-season assessments included resting ECG, blood pressure, blood biochemistry, and three 24 h dietary recalls. Results: All ECG parameters were physiological, and no significant differences (p < 0.05) were observed in heart rate, PR interval, or QTc between groups. However, HA group exhibited higher systolic blood pressure and a short QT interval. Lactate was significantly higher in HA (p = 0.028). The HA diet contained more saturated fat (p < 0.001), cholesterol (p = 0.013), magnesium (p = 0.003) and potassium (p = 0.001), whereas LA athletes consumed more glucose (p = 0.024). In HA, total energy expenditure correlated positively (p ≥ 0.05) with QRS (ρ = 0.52) and QT (ρ = 0.56), while heart rate correlated inversely with vitamin D (ρ = −0.59). In LA, QTc showed strong inverse correlations with zinc (ρ = −0.62) and selenium (ρ = −0.85). Conclusions: This finding suggests that intermittent high-altitude training did not alter ECG patterns when nutrient intake was adequate. High lactate level and specific nutrient correlations point to a residual physiological load and a modulatory role of electrolytes, B-vitamins, and vitamin D on cardiac repolarisation. Full article

Artificial (technical) snow production is an increasingly common practice in alpine regions, yet little is known about its role in shaping microbial communities at the molecular level. In this study, we combined culture-based methods with high-throughput 16S rRNA gene sequencing and functional trait prediction (FAPROTAX) to investigate bacterial communities across the full technical snowmaking cycle in one of Polish ski resorts. The molecular profiling revealed that technical snow harbors dominant taxa with known cold-adaptation mechanisms, biofilm-forming abilities, and stress tolerance traits (e.g., Brevundimonas, Lapillicoccus, Massilia, with a relative abundance of 2.95, 2.14, 3.38 and 5.61%, respectively). Functional inference revealed a consistent dominance of chemoheterotrophy (up to 38% in relative abundance) and aerobic chemoheterotrophy (up to 36%), with localized enrichment of fermentation (6.9% in cannon filter and 6.5% in sediment) and aromatic compound degradation (3.7% in source waters, 3.8% in cannon filter and 4.6% in sediment). Opportunistic and potentially pathogenic genera (e.g., Acinetobacter, Flavobacterium, Nocardia) persisted in sediments (7.4%, 21.4% and 3.5%) and meltwater (34.9% and 2.31% for the latter two), raising concerns about their environmental reintroduction. Our findings indicate that technical snowmaking systems act as selective environments not only for microbial survival but also for the persistence of molecular traits relevant to environmental resilience and potential pathogenicity. Our study provides a molecular ecological framework for assessing the impacts of snowmaking on alpine ecosystems and underscores the importance of monitoring microbial functions in addition to taxonomic composition. Full article

Background and Objectives: Distal upper limb injuries are frequent in winter sports, but their functional impact is often underestimated. This study aimed to describe the epidemiology, mechanisms, and risk factors for injuries involving the forearm, wrist, hand, and fingers sustained during two consecutive winter seasons in the Italian Dolomites. Materials and Methods: All adult and willing patients presenting to the Emergency Department of Brixen Hospital after ski- or snowboard-related accidents between December 2023 and March 2025 completed a standardized 23-item questionnaire on demographics, experience level, environmental factors, equipment, and trauma mechanism. For the aim of this study only distal upper limb injuries were extracted and analyzed. Statistical analyses compared fracture versus non-fracture injuries, “good” versus “bad” fractures (AO classification and surgical complexity), and isolated ulnar collateral ligament (UCL) injuries. Results: A total of 195 patients were analyzed: 96 (49.2%) sustained a fracture and 33 (16.9%) presented with isolated UCL lesions. Fractures occurred more frequently on blue slopes (56.2% vs. 33.3%, p < 0.001), whereas non-fracture injuries predominated on red and off-piste slopes. Age, BMI, and skill level did not differ significantly between groups. Surgically classified complex distal forearm fractures were significantly more frequent in females (p < 0.005) but were not associated with environmental factors. UCL injuries occurred mainly on red slopes (54.5%) and were often related to pole entrapment during falls. None of the injured patients reported the use of protective wrist or thumb supports. Conclusions: Distal upper limb injuries are a common pattern of alpine sports trauma, with wrist fractures and skier’s thumb being predominant lesions. Low-speed falls on easy slopes are associated with wrist fractures, while UCL injuries are linked to intermediate slopes. Preventive strategies should include fall technique education, protective gloves, and improved pole ergonomics. Full article

The rapid expansion of ski tourism and climate change-induced snow shortages have led to intensified ski run maintenance, including extensive earthworks, artificial snowmaking, and regular snow grooming. While these activities are known to cause significant land degradation, quantitative geomorphological studies, specifically on the effects of snow grooming, are limited. This study addresses this knowledge gap by quantitatively assessing the impact of snow grooming on erosion processes and hillslope morphology by comparing them with natural landforms. We achieved this by determining the spatial distribution, morphometry, and long-term persistence of studied landforms. The study area consisted of a unique ski resort at Kasprowy Wierch, which does not use artificial snowmaking or extensive earthworks. We combined detailed field mapping with the analysis of multi-temporal Digital Elevation Models (DEMs) and orthophotos from 2012, 2019, 2020, and 2023. Our methodology also included the calculation of volumetric changes using the DEM of Difference (DoD) analysis. We distinguished two groups of eroded areas, natural landforms (e.g., shallow landslides, debris flow tracks, nivation niches) and snow groomer-induced forms, which were concentrated on ski runs. Natural landforms were elongated and deeper, with higher edges, clustered along debris flow tracks, and occurred on steeper slopes (mean 26.8°). They were more persistent and extensive, with a total area ranging from 3891 m² in 2012 to 3452 m² in 2023. In contrast, groomer-eroded landforms, located on gentler slopes (mean 23.4°), were smaller, more angular, less persistent, and concentrated on narrower, intensively used ski run sections. Their total area decreased from 2122.71 m² to 1762.25 m² over the same period, despite an increase in their count. The volumetric analysis revealed distinct dynamics: over the long term (2012–2023), natural forms showed a total deposition of +8.196 m³, while groomer-eroded forms experienced total erosion of −2.070 m³. During an extreme rainfall event in 2020, natural landforms experienced vast erosion of −163.651 m³, nearly five times greater than the −33.765 m³ observed on snow groomer-eroded landforms, demonstrating their greater susceptibility to high-magnitude events. Importantly, a comparison with other studies reveals that the scale of erosion from snow grooming is relatively small compared to the severe impacts of artificial snowmaking. Our findings are relevant for managing protected areas, such as Tatra National Park, where the focus should be on mitigating anthropogenic impacts to preserve natural processes, which in turn implies that the development of new ski infrastructure should be prohibited. Full article

Background: Great physical requirements are necessary to maintain the entire body in a streamlined and aerodynamic position during downhill skiing. Balance control has an important role in alpine skiing and depends on muscle endurance and strength. The central processing of proprioception and the force capacity of muscle are altered by fatigue. The objective of this study was to assess the effects of fatigue and visual input on balance control in alpine skiing. Methods: Eleven male professional skiers participated in the study. Balance control with eyes open and eyes closed was assessed before and after performing a maximal effort specific alpine ski test. Variables: the total travel distance (TTD) (mm), radial area (RA) (mm²), ratio between TTD and RA (TTD/RA) (1/mm), mean center of pressure (COP) velocity (total length of the COP path per unit time) (mm/s), the mean mediolateral (ML) COP oscillation velocity (Lat_Vel) (mm/s), the mean anteroposterior (AP) COP oscillation velocity (AP_Vel) (mm/s), mean ML (MLD) (mm) and mean AP (APD) (mm) displacements of the COP and the distance from the ordinate origin (mean X and mean Y) (theoretical point where the COP should be) to the point at which the COP is located, and heart rate were measured. Results: The results showed differences in the variables related to postural control and balance before and after the stress test (p = 0.002–0.037). However, no differences were found when the results obtained with open and closed eyes were compared. Conclusions: The results showed that performance in alpine skiing could be negatively affected by fatigue. However, the dynamic parameters are not decreased by visual input during muscle fatigue. Full article

In alpine skiing, accurate and real-time estimation of body pose and inclinations due to turning is critical as it demonstrates the skier’s turning behavior and abilities. Although inertial measurement units (IMUs) ease measuring kinematics in extreme conditions and provide such indications of skiers’ behavior, they often suffer from sensor placement and orientation variability. This study explains the impact of sensor placement and orientation on the captured signals and proposes a preprocessing algorithm that can rotate raw signals from various locations and orientations similar to those near the Center of Mass (CoM). The preprocessing algorithm involves a sensor fusion approach using a quaternion-based complementary filter (CF) to rotate raw signals and extract turning motions via the global wavelet spectrum. Our experiment, validated on data collected from 14 sensors including two smartphones placed on different body parts during skiing sessions, demonstrates that the preprocessing algorithm can effectively reconstruct side motions, represent skiing turns, and detect turns independent of sensor placement and orientation. In field experiments with six skiers, the suggested preprocessing algorithm consistently detected skiing turns with an overall RMSE of 0.77 and MAE of 0.50 on all of the sensors relative to a reference sensor. Full article

Limited research has explored the impact of balance training on young alpine skiers, despite its recognized importance in the sport. This study evaluated the effects of a 10-week dry-land balance training program on the balance and skiing technique of skiers aged 9–11 years. The program employed five training modalities: neuromuscular, plyometric, core stability, proprioceptive, and equipment-based balance training. Thirty participants were divided into experimental and control groups based on their initial SKI IQ scores. The assessments included static balance (BTS P-Walk), explosive power (BTS G-Walk), and on-snow metrics (SKI IQ; balance, pressure, and edging) using CARV technology. The statistical analysis revealed significant improvements in the experimental group for the SKI IQ (F = 13.239; p = 0.001; η² = 0.321) in terms of the balance metric (F = 4.800; p = 0.037) and pressure metric (F = 8.084; p = 0.008), and for the static balance parameters, such as mediolateral stability in a two-legged stance (F = 4.304; p = 0.047; η² = 0.133) and anteroposterior stability in eyes-closed conditions (F = 14.249; p = 0.001; η² = 0.337). The single-leg stance stability and explosive force (F = 6.08; p = 0.02) also showed marked enhancements. The edging performance, however, showed no significant change. This study underscores the value of balance training for enhancing young skiers’ performance metrics and highlights wearable technology as an effective tool for real-time feedback. Integrating balance-focused programs into alpine skiing preparation can boost performance. Full article