Enhancing Return to Alpine Skiing: Integrating Perceptual-Motor-Cognitive Considerations in Testing and Progressions: A Clinical Commentary.

Alpine skiing poses significant risks for anterior cruciate ligament (ACL) injury at both recreational and professional levels, which is compounded by high rates of re-injury. Despite the existence of return to sport (RTS) and return to snow protocols, the frequency of ACL re-injury has not been mitigated, raising doubts about protocol effectiveness. Current RTS protocols primarily focus on biomechanical and neuromuscular factors in isolation, neglecting the important perceptual-motor-cognitive changes associated with ACL injuries and the high cognitive demands of skiing. The purpose of this clinical commentary is to address the perceptual-motor-cognitive demands specific to alpine skiing, evaluate RTS testing for skiers, and propose updated standards for testing and return to snow progressions that incorporate these considerations. Level of Evidence: 5.

IMU Data-Driven and PCA-Based Approach to Establish Quantifiable and Practically Applicable Measures for V2 Technique Elements in Cross-Country Skiing.

Quantifying movement coordination in cross-country (XC) skiing, specifically the technique with its elemental forms, is challenging. Particularly, this applies when trying to establish a bidirectional transfer between scientific theory and practical experts' knowledge as expressed, for example, in ski instruction curricula. The objective of this study was to translate 14 curricula-informed distinct elements of the V2 ski-skating technique (horizontal and vertical posture, lateral tilt, head position, upper body rotation, arm swing, shoulder abduction, elbow flexion, hand and leg distance, plantar flexion, ski set-down, leg push-off, and gliding phase) into plausible, valid and applicable measures to make the technique training process more quantifiable and scientifically grounded. Inertial measurement unit (IMU) data of 10 highly experienced XC skiers who demonstrated the technique elements by two extreme forms each (e.g., anterior versus posterior positioning for the horizontal posture) were recorded. Element-specific principal component analyses (PCAs)-driven by the variance produced by the technique extremes-resulted in movement components that express quantifiable measures of the underlying technique elements. Ten measures were found to be sensitive in distinguishing between the inputted extreme variations using statistical parametric mapping (SPM), whereas for four elements the SPM did not detect differences (lateral tilt, plantar flexion, ski set-down, and leg push-off). Applicability of the established technique measures was determined based on quantifying individual techniques through them. The study introduces a novel approach to quantitatively assess V2 ski-skating technique, which might help to enhance technique feedback and bridge the communication gap that often exists between practitioners and scientists.

Traumatic Triceps and Medial Ulnar Collateral Ligament Rupture in an Adolescent Mogul Skier: A Case Report.

Triceps tendon ruptures are uncommon injuries that account for less than 1% of all upper extremity tendon injuries. Medial ulnar collateral ligament injury (mUCL), while common in overhead athletes as a result of valgus forces during the throwing mechanics, has scarcely been reported in non-overhead, throwing individuals. Traumatic assault to the elbow may result in the rupture of the triceps tendon with concomitant mUCL injury. As such an injury pattern typically presents in middle-aged males, weightlifters, or American football players from eccentric overloading of the elbow. We present an adolescent, elite-level, competitive skier with traumatic onset distal triceps rupture with concomitant medial ulnar collateral ligament rupture suffered via a fall on an outstretched hand (FOOSH) mechanism. Magnetic resonance imaging (MRI) showed acute full-thickness avulsion of the distal triceps tendon occurring at the olecranon enthesis. An open tendon repair was performed, and the patient was able to report significant symptom resolution over the course of six months postoperatively and successfully return to elite-level competition. This was a unique and rare case of triceps tendon rupture with concomitant mUCL injury in an adolescent via a non-contact, high-velocity injury mechanism. While a rare injury combination, this case nevertheless identifies an area of research not currently extensively covered-trampoline training and associated injuries in adolescents. This case, therefore, not only adds a novel dimension to the understanding of triceps and mUCL injuries in young athletes but also underscores the need for heightened awareness and specific safety protocols in sports training involving equipment like trampolines.

Skiing Injuries in the US Pediatric Population: An Analysis of National Injury Trends and Mechanisms Between 2012 and 2022.

Background: While prevention protocols have been implemented, skiing-related musculoskeletal injuries and concussions continue to present to emergency departments in the United States. Previous literature has suggested the pediatric population may constitute up to 40% of skiing-related injuries. Purpose: To assess injury trends and the underlying mechanisms of skiing injuries in pediatric patients seen at emergency departments in the United States. Study Design: Descriptive epidemiology study. Methods: The National Electronic Injury Surveillance System (NEISS) was queried for pediatric (age ≤18 years) skiing injuries between January 1, 2012, and December 31, 2022. Injury mechanism, location, disposition, and diagnosis were recorded, and the statistical sample weight assigned by NEISS by hospital was used to calculate national estimates (NEs). Injury trends were evaluated with linear regression analysis. Results: Overall, 2951 pediatric skiing injuries were included (NE = 123,386). The mean age of the patients was 12.4 ± 3.5 years, with 61.3% of the injuries occurring in male patients. Impact with the ground was the most common injury mechanism (NE = 87,407; 70.8%). Fractures were the most common diagnosis (NE = 38,527, 31.2%), followed by strains/sprains (NE = 22,562, 18.3%), contusions/abrasions (NE = 16,257, 13.2%), and concussions (NE = 12,449, 10.1%). The lower leg was the most common fracture site (NE = 9509, 24.7%), followed by the shoulder (NE = 7131, 18.5%) and lower arm (NE = 5876, 15.3%). Analysis of annual injuries revealed no significant trend between 2012 and 2022 (P = .17), with fluctuations apparent throughout the study period. Significant decreases were seen in strains/sprains (P < .01) and contusions/abrasions (P < .01), but not in concussions (P = .57) or fractures (P = .70). Conclusion: Impacts with the snow/ground made up 70.8% of all injuries. Fractures were the most common injury diagnosis, followed by strains/sprains, with the lower leg being most frequently fractured. While strains/sprains and contusions/abrasions showed a significant decline, there were no significant trends in fractures and concussions between 2012 and 2022.

'I want to ski and race, not just ski': a qualitative study on athletes' and stakeholders' perspectives on return-to-sport in high-performance Snowsports.

This study explored stakeholders' perspectives on current practices, challenges and opportunities related to the return-to-sport (RTS) process in high-performance Snowsports. We conducted fourteen semi-structured interviews with athletes, coaches and health professionals from multiple countries using online video platforms. The data were transcribed verbatim and analysed based on constant comparative analysis employing the principles of Grounded Theory. Codes were grouped into categories and main concepts and a conceptual model were derived. According to the participants, RTS should be considered a continuous process to bring the athlete back to competition as fast and safely as possible, whereas speed is often prioritised over safety. Participants described the need for a structured and criteria-based process. Despite the multiple phases and the diversity of involved professionals, the process is individualised and unique, highlighting the value of having the athlete at the centre of the RTS process. It was considered essential to provide a safe environment and build trustworthy relationships. Additionally, access to resources, communication and cooperation among all experts was perceived as critical to successful RTS. Our participants described the value of continuity and an athlete-centred approach to the RTS process. The challenges, such as interprofessional communication, the lack of objective sport-specific criteria, and the diversity of resources and network structures, were perceived as practical issues that influenced the process, which should be tailored for each athlete accordingly to reach a successful RTS.

The Characteristics of Endurance Events with a Variable Pacing Profile-Time to Embrace the Concept of "Intermittent Endurance Events"?

A variable pacing profile is common in different endurance events. In these races, several factors, such as changes in elevation or race dynamics, lead participants to perform numerous surges in intensity. These surges are so frequent that certain events, such as cross-country (XC) skiing, mountain biking (MTB), triathlon, and road cycling, have been termed "intermittent endurance events". The characteristics of these surges vary depending on the sport: MTB and triathlon require athletes to perform numerous short (<10 s) bouts; XC skiing require periods of short- and moderate-(30 s to 2 min) duration efforts, while road cycling is comprised of a mix of short-, moderate-, and long-duration (>2 min) bouts. These bouts occur at intensities above the maximal metabolic steady state (MMSS), with many efforts performed at intensities above the athletes' maximal aerobic power or speed (MAP/MAS) (i.e., supramaximal intensities). Given the factors that influence the requirement to perform surges in these events, athletes must be prepared to always engage in a race with a highly stochastic pace. The aim of this review is to characterize the variable pacing profile seen in endurance events and to discuss how the performance of multiple maximal and supramaximal surges in intensity can affect how athletes fatigue during a race and influence training strategies that can lead to success in these races.

Beyond the Slopes and Highways: Endovascular Repair of Blunt Traumatic Aortic Injuries after Skiing versus Motor Vehicle Accidents.

Background: Blunt traumatic aortic injury (BTAI) is a potentially fatal condition, typically resulting from high-velocity trauma. To date, little is known about this type of injury among skiers, who form the largest patient cohort with aortic injuries in the alpine region of Tyrol, Austria. Methods: This retrospective, single-center study at the University Hospital of Innsbruck analyzed patients who underwent endovascular treatment for blunt traumatic aortic injury from 2005 to 2023. Patient data were extracted from electronic and digitalized medical history records. Subsequent analyses compared the baseline characteristics and clinical results of the skiing accident (SA) group to the motor vehicle accident (MVA) group. Results: A total of 48 BTAI patients receiving TEVAR were included, 25 (52%) from SAs versus 23 (48%) from MVAs, who were predominantly male (92% vs. 78.3%). Despite similar preoperative risk profiles and ASA Scores (1.44 vs. 1.74) and no marked differences in BTAI injury grades or the affected aortic zones, significant disparities emerged: the SA group experienced shorter median ICU stays (3 vs. 11 days, p = 0.0007), fewer concomitant injuries (5 vs. 7, p = 0.005), and lower Injury Severity Scores (ISSs) (29 vs. 33, p = 0.003) than their MVA counterparts. The presence of rib fractures alongside other thoracic injuries, such as lung injury, pneumothorax, or hemothorax, was strongly correlated with BTAI in patients following skiing accidents (OR = 128.5). Conclusions: The injury severities and locations of BTAI in SA patients were comparable to those in MVA patients, indicating similar mechanisms of thoracic trauma. However, the SA patients experienced fewer concurrent pelvic and extremity fractures, had less post-procedural morbidity, and required shorter ICU stays. The presence of rib fractures combined with other thoracic injuries strongly suggests BTAI. These indicators should lead to prompt imaging and appropriate therapy.

Jump performance and movement quality in 7- to 15-year-old competitive alpine skiers: a cross-sectional study.

INTRODUCTION: Injury rates in competitive alpine skiing are high. With current methods, identifying people at risk is expensive and thus often not feasible at the youth level. The aims of this study were (1) to describe the jump performance and movement quality of youth competitive alpine skiers according to age and sex, (2) to compare the jump distance among skiers of different sexes and movement quality grades, and (3) to assess the inter-rater grading reliability of the qualitative visual movement quality classification of such jumps and the agreement between live and video-based post-exercise grading. MATERIALS AND METHODS: This cross-sectional study is based on an anonymized dataset of 301 7- to 15-year-old competitive alpine skiers. The skiers performed two-legged forward triple jumps, whereby the jump distance was measured, and grades were assigned by experienced raters from the frontal and sagittal perspectives depending on the execution quality of the jumps. Furthermore, jumps were filmed and ultimately rated post-exercise. Differences in jump distance between various groups were assessed by multivariate analyses of variance (MANOVAs). Reliability was determined using Kendall's coefficient of concordance. RESULTS: The jump distance was significantly greater in U16 skiers than in U11 skiers of both sexes and in skiers with good execution quality than in those with reduced or poor execution quality. Overall, jump distance in U16 skiers significantly differed between female (5.37 m with 95% CI [5.21, 5.53]) and male skiers (5.90 m with 95%CI [5.69, 6.10]). Slightly better inter-rater grading reliability was observed for video-based post-exercise (strong agreement) ratings than for live ratings (moderate agreement). CONCLUSION: In competitive alpine skiers aged 7 to 15 years, jump performance increases with age, and around puberty, sex differences start to manifest. Our results highlight the importance of evaluating both jump distance and movement quality in youth skiers. To improve test-retest reliability, however, a video-based post-exercise evaluation is recommended.

In youth competitive alpine skiers, jump performance and movement quality matter, and both should be trained and tested.A qualitative assessment of movement quality while jumping by experts is a highly scalable and cost-effective approach; however, to ensure sufficient test-retest reliability, the assessment criteria need to be standardised and an additional video-based post-exercise assessment is recommended.

Exploring the effect of the menstrual cycle or oral contraception on elite athletes' training responses when workload is not objectively quantifiable: the MILS approach and findings from female Olympians.

Objectives: Develop the Markov Index Load State (MILS) model, based on hidden Markov chains, to assess athletes' workload responses and investigate the effects of menstrual cycle (MC)/oral contraception (OC), sex steroids hormones and wellness on elite athletes' training. Methods: On a 7-month longitudinal follow-up, daily training (volume and perceived effort, n=2200) and wellness (reported sleep quality and quantity, fitness, mood, menstrual symptoms, n=2509) data were collected from 24 female rowers and skiers preparing for the Olympics. 51 MC and 54 OC full cycles relying on 214 salivary hormone samples were analysed. MC/OC cycles were normalised, converted in % from 0% (first bleeding/pill withdrawal day) to 100% (end). Results: MILS identified three chronic workload response states: 'easy', 'moderate' and 'hard'. A cyclic training response linked to MC or OC (95% CI) was observed, primarily related to progesterone level (p=8.23e-03 and 5.72e-03 for the easy and hard state, respectively). MC athletes predominantly exhibited the 'easy' state during the cycle's first half (8%-53%), transitioning to the 'hard' state post-estimated ovulation (63%-96%). OC users had an increased 'hard' state (4%-32%) during pill withdrawal, transitioning to 'easy' (50%-60%) when on the pill. Wellness metrics influenced the training load response: better sleep quality (p=5.20e-04), mood (p=8.94e-06) and fitness (p=6.29e-03) increased the likelihood of the 'easy' state. Menstrual symptoms increased the 'hard' state probability (p=5.92e-02). Conclusion: The MILS model, leveraging hidden Markov chains, effectively analyses cumulative training load responses. The model identified cyclic training responses linked to MC/OC in elite female athletes.

Research application of session-RPE in monitoring the training load of elite endurance athletes.

Purpose: TRIMP and sRPE are both representative indicators of training load(TL), and the correlation between two has been widely demonstrated across various sports. The aim of this study was to investigate the reliability of sRPE-TRIMP correlation across different intensities/duration of training in cross-country skiing, and whether sRPE can serve as an validity supplement to TRIMP data in cases of lost heart rate data. Method: 10 athletes were used as the experimental objects. The intensity, duration and RPE of 273 different types of training sessions were collected, and statistical methods were used for data analysis. Results: 1. There was a significant correlation between sRPE and TRIMP (r = 0.68, p < 0.05), but the correlation differs among the LIT, MIT and HIT groups (r = 0.70, 0.46, r = 0.31, p < 0.05) 2. sRPE-TRIMP correlation among three different time duration in the LIT group (0-60 min, 60-120 min and 120-180 min), are all highly significant (r = 0.70, 0.67, 0.69, p < 0.05) and the LRsRPE-TRIMP of 3 duration have no significant differences (chow test, p > 0.05). 3. The difference in actual training duration between samples was the main reason for the difference in the application effect of sRPE, because the actual training duration ratio of LIT was 89.7 ± 16.4%; MIT, 98.5 ± 6.2%; and HIT, 94.4 ± 13.5%. Conclusion: 1. The linear relationship between sRPE and TRIMP (LRsRPE-TRIMP) is more significant in LIT compared to that in MIT and HIT. 2. Variations in the duration of LIT sessions do not affect the consistency of the relationship between sRPE and TRIMP. 3. Discrepancies between actual and planned training durations directly impact the significance of the LRsRPE-TRIMP.

Return to athletics after total knee arthroplasty: a survey study of 784 recreational athletes across 12 sports.

BACKGROUND: Postoperative return to recreational activity is a common concern among the increasingly active total knee arthroplasty (TKA) patient population, though there is a paucity of research characterizing sport-specific return and function. This study aimed to assess participation level, postoperative return to activity, sport function, and limitations for recreational athletes undergoing TKA. METHODS: A survey of recreational sports participation among primary, elective TKA patients from a single academic center between June 2011 and January 2022 was conducted. Of the 10,777 surveys administered, responses were received from 1,063 (9.9%) patients, among whom 784 indicated being active in cycling (273 [34.8%]), running (33 [4.2%]), jogging (68 [8.7%]), swimming (228 [29.1%]), tennis (63 [8.0%]), skiing (55 [7.0%]), or high-impact team sports (64 [8.2%]) between two years preoperatively and time of survey administration, and were included for analyses. RESULTS: Cycling (62.3% at two years preoperatively vs. 59.0% at latest follow-up) and swimming (62.7% at two years preoperatively vs. 63.6% at latest follow-up) demonstrated the most favorable participation rate changes, while running (84.0% at two years preoperatively vs. 48.5% at latest follow-up) and skiing (72.7% at two years preoperatively vs. 45.5% at latest follow-up) demonstrated the least favorable participation rate changes. The majority of respondents were "satisfied" or "very satisfied" with their return across all sports, though dissatisfaction was highest among runners and joggers. For cycling, running, jogging, and swimming, respondents most commonly reported no change in speed or distance capacity, though among these cyclists reported the highest rates of improved speed and distance. The majority of returning skiers reported improved balance, form, and ability to put on skis. CONCLUSION: Return to sport is feasible following TKA with high satisfaction. Swimming and cycling represent manageable postoperative activities with high return-rates, while runners and joggers face increased difficulty returning to equal or better activity levels. Patients should receive individualized, sports-specific counseling regarding their expected postoperative course based on their goals of treatment.

Death Following a Skiing Incident: Severe Exsanguination Due to Rupture of the Left Renal Artery.

With the growing popularity of winter sports, it is necessary to pay more attention to the types of traumatic injuries that a person can sustain in various incidents related to their practice. We present a case in which an adult man died as a result of a collision with a tree while skiing. Although the deaths are associated with different types and severity of craniocerebral injuries in the majority of the cases, here we are dealing with an abdominal injury with rupture of the stomach, pancreas, and left renal artery. The exact localization of the resulting traumatic injuries and the mechanism of their occurrence were examined. Both macroscopic autopsy findings (gross pathology) and histologically proven ones are presented and described. Presenting this case, we want to raise awareness of the different types of injuries received while skiing, as well as to emphasize the possibility of death in the absence of visible external injuries over the victim's body.

Performance and micro-pacing in sprint cross-country skiing: A comparison of individual time-trial and head-to-head race formats.

This study compared performance strategies and sub-technique selection in cross-country skate skiing sprint races, specifically individual time-trial (ITT) and head-to-head (H2H) formats. Fourteen male cross-country skiers from the Chinese national team participated in the FIS-sanctioned sprint race day. GNSS and heart rate sensors recorded positioning, skiing speeds, heart rate, sub-technique usage, and skiing kinematics. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with section time. One-way analyses of variance were used to examine differences between the ITT and H2H. H2H race speeds were 2.4 ± 0.2% faster than the ITT race (p < 0.05).Variations in sub-technique and skiing kinematics were observed between race formats, indicating different strategies and tactics employed by athletes. SPM identified specific clusters (primarily uphill) where the fastest athlete gained significant time over the slowest. The greatest time gains were associated with higher G3 sub-technique usage and longer G3 cycle length on steep uphill terrain (9-13% gradients). Integrating SPM analyses and sub-technique assessments can help optimise performance and tactics in sprint races. This study enhances our understanding of cross-country skiing dynamics and performance variations among elite competitors.

Exercise-Induced Troponin Elevation in High-Performance Cross-Country Skiers.

Background: Troponin I and T are biomarkers to diagnose myocardial infarction and damage. Studies indicate that strenuous physical activity can cause transient increases in these troponin levels, typically considered physiological. However, current data show differences in the exercise-induced increase in troponin I and T in elite athletes. Method: This prospective clinical study aimed to determine troponin I and T levels in 36 top cross-country skiers of the German national team (18 male, 18 female) after a standardized competition load over two days. All study participants underwent a comprehensive sports medical and cardiological evaluation, including ECG and echocardiography. A multivariable regression analysis was utilized to identify possible predictors of increased troponin I levels. Results: Only three male athletes (8.1%) showed an isolated increase in Troponin I (Ø 112.49 ng/L, cut off < 45.2 ng/L), while no increase in troponin T in the study population was detected. Conclusions: The analysis suggested several potential predictors for increased troponin I levels, such as height, weight, weekly training hours, and indications of an enlarged sports heart, though none achieved statistical significance. Knowing the different exercise-induced detectability of the various troponins in the clinical setting is essential.

Neurological outcome of cardiac arrest patients in mountain areas: An analysis of the Northern French Alps Emergency Network.

BACKGROUND: Mountainous areas pose a challenge for the out-of-hospital cardiac arrest (OHCA) chain of survival. Survival rates for OHCAs in mountainous areas may differ depending on the location. Increased survival has been observed compared to standard location when OHCA occurred on ski slopes. Limited data is available about OHCA in other mountainous areas. The objective was to compare the survival rates with a good neurological outcome of OHCAs occurring on ski slopes (On-S) and off the ski slopes (OffS) compared to other locations (OL). METHODS: Analysis of prospectively collected data from the cardiac arrest registry of the Northern French Alps Emergency Network (RENAU) from 2015 to 2021. The RENAU corresponding to an Emergency Medicine Network between all Emergency Medical Services and hospitals of 3 counties (Isère, Savoie, Haute-Savoie). The primary outcome was survival at 30 days with a Cerebral Performance Category scale (CPC) of 1 or 2 (1: Good Cerebral Performance, 2: Moderate Cerebral Disability). RESULTS: A total of 9589 OHCAs were included: 213 in the On-S group, 141 in the Off-S group, and 9235 in the OL group. Cardiac etiology was more common in On-S conditions (On-S: 68.9% vs OffS: 51.1% vs OL: 66.7%, p < 0.001), while Off-S cardiac arrests were more often due to traumatic circumstances (OffS: 39.7% vs On-S: 21.7% vs OL: 7.7%, p < 0.001). Automated external defibrillator (AED) use before rescuers' arrival was lower in the Off-S group than in the other two groups (On-S: 15.2% vs OL: 4.5% vs OffS: 3.7%; p < 0.002). The first AED shock was longer in the Off-S group (median time in minutes: OffS: 22.0 (9.5-35.5) vs On-S: 10.0 (3.0-19.5) vs OL: 16.0 (11.0-27.0), p = 0.03). In multivariate analysis, on-slope OHCA remained a positive factor for 30-day survival with a CPC score of 1 or 2 with a 1.96 adjusted odds ratio (95% confidence interval (CI), 1.02-3.75, p = 0.04), whereas off-slope OHCA had an 0.88 adjusted odds ratio (95% CI, 0.28-2.72, p = 0.82). CONCLUSIONS: OHCAs in ski-slopes conditions were associated with an improvement in neurological outcomes at 30 days, whereas off-slopes OHCAs were not. Ski-slopes rescue patrols are efficient in improving outcomes.

Tumor-Like Distal Femoral Cortical Irregularities of the Knee in Adolescent Competitive Alpine Skiers: Longitudinal Assessment Over 48 Months.

BACKGROUND: Tumor-like distal femoral cortical irregularities (DFCIs) are a frequent incidental finding on knee magnetic resonance imaging (MRI) and are common in young competitive athletes. PURPOSE: To assess and compare the morphology and prevalence of DFCIs in competitive alpine skiers over 48 months during adolescence. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Adolescent competitive alpine skiers were prospectively recruited in 2018 and received bilateral 3-T MRI of the knee at baseline and after 48 months. All MRIs were evaluated for the presence and location of DFCIs, which were marked at 1 of 3 anatomic positions: (1) the femoral attachment of the medial head of the gastrocnemius muscle, (2) the lateral head of the gastrocnemius muscle, or (3) the attachment of the adductor magnus aponeurosis. The size of the DFCI was measured by 2 radiologists independently. The measurements were compared using the Wilcoxon signed-rank test, the interclass correlation coefficient (ICC), and Cohen Kappa. RESULTS: A total of 63 athletes (mean age at follow-up, 19.6 ± 1.2 years; n = 25 female) were included in the study. At baseline, DFCIs were detected in 84 out of 126 knees (67%). At the 48-month follow-up, DFCIs were found in 88 out of 126 knees (70%), with multiple DFCIs in 3 knees and no significant difference between male and female patients (n = 24 male, n = 19 female; P = .71). No significant increase was detected for the number (P = .21) and size of the DFCIs between the baseline and the 48-month follow-up (mean size: baseline, 3.7 ± 0.8 mm; 48-month follow-up: 3.6 ± 0.9 mm; P = .66). The interrater agreement for the mean size measurements of DFCIs was good to excellent (ICC 0.88). CONCLUSION: DFCIs remain a frequent finding on knee MRI in competitive alpine skiers after skeletal maturation and do not disappear during adolescence. The DFCI size was constant in athletes aged between 15 and 19 years. Moreover, DFCIs should not be mistaken for a pathologic finding.

Changes in roller skiing economy among Nordic combined athletes leading up to the competition season.

The purpose of this study was to compare roller skiing economy during different training phases in Nordic combined (NC) athletes and determine the aerobic and anaerobic factors responsible for changes in skiing economy. Seven elite NC athletes underwent incremental load tests on a large buried treadmill in both spring and autumn using roller skis. Measurements included oxygen uptake, respiratory exchange ratio, and blood lactate concentration. Roller skiing economy was calculated from aerobic and anaerobic energy system contributions, and overall roller skiing economy was determined by combining the two. Comparisons were made between the skiing economies obtained in the two measurement sessions. Physical characteristics and incremental test performance remained consistent between the two measurement sessions. The overall skiing economy at each speed significantly improved toward the competition season (p < 0.05). Similarly, the contribution of anaerobic energy system at each speed showed significant improvement (p < 0.05). In contrast, the contribution of aerobic energy system did not change between the two measurement sessions. This study reveals that NC athletes enhance their skiing economy at the same speed during submaximal efforts in preparation for the competition season. This improvement is predominantly associated with an improvement in the contribution of anaerobic energy system.

Skiing economy and kinematic during a field double poling roller skiing among novice and experienced cross-country skiers.

To assess the skiing economy (SE) and kinematics during double poling (DP) roller skiing between two groups of skiers in a field setting. Five experienced and five novice male skiers performed a SEDP test at 16 km∙h-1 on an outdoor athletics track. Gas exchange parameters were measured to determine SEDP. A two-dimensional video was filmed to measure the kinematics variables. Experienced skiers exhibited a 21% lower oxygen cost than novice skiers (p = 0.016) in DP, indicating a strong association between SEDP, cycle length and cycle rate (p < 0.001). Additionally, before the poling phase, experienced skiers manifested significantly greater maximum hip and knee extension angles than novice skiers (p < 0.001). During the poling phase, experienced skiers with a greater pole plant angle (p = 0.001), longer flexion time (p < 0.001) and higher flexion angular velocity in the elbow joint (p < 0.05) demonstrated better SEDP. There was an interaction effect of the one-repetition maximum bench press × group in SEDP (b = - 0.656, SE = 0.097, t = - 6.78, p = 0.001). Therefore, experienced skiers with better SEDP demonstrated more efficient cycles, potentially accomplished using dynamic full-body DP motion to ascertain effective propulsion. Combined upper body strength and ski-specific skill training may enhance SEDP in novice skiers.

Terrain park injuries and risk factors in western Canadian resorts, 2008-2009 to 2017-2018: insights for risk management.

Terrain parks (TP) are popular attractors to snowsport resorts for both skiers and snowboarders, however there is some concern about the risk of severe injury. TP risk management needs to balance the business case against the human cost of injury. To inform effective TP risk management strategies, it essential to understand risk factors, and injury frequency and severity. To this end, a retrospective inductive analysis of Canada West Ski Areas Association's Accident Analyzer database (2008-2009 to 2017-2018). Inclusion criteria., (i) at least 8 seasons of matching injury and participation data, (ii) minimum of 10 TP injuries p.a., (iii) activity either skiing or snowboarding, and (iv) injury location was coded as terrain park/rail. Data was excluded for ticket type N/A. Anonymised and deidentified secondary data was entered into SPSS for analysis. Between group differences were explored via χ2 analysis with Yates' Continuity Correction for 2 × 2 tables and an inductive data driven approach to explore other factors. From this data, 12,602 injuries were in TPs across 28 resorts. 11,940 (94.7%) met the inclusion criteria (14.2% female; 86.5% <25 years; 73.0% snowboarders. 50.8% were male snowboarders <25 years). Higher levels of helmet use were not correlated with a decline in reported head injuries. Day-ticket holders were more likely to be injured on their first two uses of a run than season pass holders. More snowboarders injured in TPs (59.7%) went to hospital than skiers (51.0%). Thus, participants injured in TP are typically younger, male, and snowboarders with either a Season Pass or day ticket, thus potentially a distinct target group for injury mitigation and prevention strategies and communications. The application of other frameworks such as the hierarchy of control and socioecological framework reflects the complex multifactorial systems in which snowsports occur and from which more targeted risk management strategies may emerge to mitigate injury risk while maintaining TP appeal.

Evaluation of 3D Markerless Motion Capture System Accuracy during Skate Skiing on a Treadmill.

In this study, we developed a deep learning-based 3D markerless motion capture system for skate skiing on a treadmill and evaluated its accuracy against marker-based motion capture during G1 and G3 skating techniques. Participants performed roller skiing trials on a skiing treadmill. Trials were recorded with two synchronized video cameras (100 Hz). We then trained a custom model using DeepLabCut, and the skiing movements were analyzed using both DeepLabCut-based markerless motion capture and marker-based motion capture systems. We statistically compared joint centers and joint vector angles between the methods. The results demonstrated a high level of agreement for joint vector angles, with mean differences ranging from -2.47° to 3.69°. For joint center positions and toe placements, mean differences ranged from 24.0 to 40.8 mm. This level of accuracy suggests that our markerless approach could be useful as a skiing coaching tool. The method presents interesting opportunities for capturing and extracting value from large amounts of data without the need for markers attached to the skier and expensive cameras.