Search

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.

Patellar tendon (PT) complaints are frequent in competitive alpine skiers and such complaints are characterized by a long-lasting affection. Since PTs are subject to maturation up to 1–2 years after growth spurt, this early career stage may be decisive for the further course of complaints. The aim of this study was to investigate the evolution of PT complaints and shear wave velocity patterns among competitive alpine skiers during a 4-year post-growth spurt follow-up. The PT complaints and SWV patterns of forty-seven skiers were analysed at baseline (i.e., immediately after their peak height growth at 13–15 years of age) and were re-analysed at 4-year follow-up. The PTs were scanned via three-dimensional SWE. Symptomatic skiers were identified based on pain sensation under loading and pressure-induced pain around the PT. The prevalence of PT complaints decreased from 29.8% at baseline to 12.8% at follow-up (Pearson’s χ2 = 9.429; p = 0.002). SWV decreased from the baseline assessment to the follow-up in the proximal and distal regions (p < 0.05). SWV coefficient of variation (CV) in the distal and mid-portion regions was greater at baseline than at follow-up (p < 0.05). At the follow-up assessment, compared to “healthy” skiers, “healed” skiers who recovered from PT complaints had lower SWVs in the proximal region (p = 0.020) and greater SWV CVs in the proximal region (p = 0.028). Moreover, symptomatic skiers had significantly greater SWV CVs in the mid-portion region than did “healthy” subjects with no history of PT complaints (p = 0.020). The average SWV was negatively correlated with the SWV (proximal: r = −0.74, p < 0.001; mid-portion: r = −0.37 p = 0.011; and distal: r = −0.58, p < 0.001). The occurrence of PT complaints decreased over a 4-year post-growth spurt follow-up. “Healed” skiers who were symptomatic at baseline had an even greater average decrease in the proximal and mid-portion SWV than “healthy” skiers with no history of PT complaints. This may lead to the hypothesis that PT complaints in adolescent skiers are not self-eliminating towards the end of adolescence, as at least structural irregularities appear to persist for several years after the onset of initial symptoms. Furthermore, “healed” and symptomatic tendons exhibited increased SWV variability, supporting the hypothesis that SWV CV may provide additional valuable information on the mechanical properties of PTs affected by overuse-related complaints.

Abstract Objectives To longitudinally assess and correlate the prevalence of superolateral Hoffa fat pad (SHFP) edema with changes in features of the knee extensor mechanism in adolescent competitive alpine skiers over 48 months. Methods Competitive alpine skiers were prospectively enrolled in 2018 and underwent bilateral knee MRI at baseline and after 48 months. MRI was assessed for the prevalence of SHFP edema. Features of the knee extensor mechanism were assessed by measuring the trochlear sulcus angle and depth, lateral and medial trochlear inclination, trochlear angle, patella tilt, Insall‒Salvati ratio (ISR), and patellar ligament to lateral trochlear facet (PL-T) distance. Separate logistic regression models were used to calculate the odds ratios between each measurement and the presence of SHFP edema at both time points. Results Sixty-three athletes were included in the study (mean age 15.3 ± 1.3 years, 25 women). At baseline, 23 knees had SHFP edema, increasing to 34 knees at the 48-month follow-up. At baseline, knees with measurements in the highest quartile for ISR and lowest quartile for trochlear depth and PL-T were 9.3, 5.1, and 7.7 times more likely to show SHFP edema, respectively. At follow-up, these correlations were confirmed and additionally, knees with measurements in the highest quartile for trochlear sulcus angle and the lowest quartile for lateral trochlear inclination were 4.1 and 3.4 times more likely to show SHFP edema. Conclusion An increased prevalence of SHFP edema in competitive alpine skiers during adolescence was associated with persistent high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet. Critical relevance statement In clinical routine, assessment of the mechanical properties of the knee extensor mechanism, together with anatomical developments during adolescence, may improve the understanding and management of patellofemoral instability. Key points • Superolateral Hoffa fat pad (SHFP) edema is a frequent cause of anterolateral knee pain but the role of predisposing factors is still debated. • A higher prevalence of SHFP edema was associated with high-riding patella, reduced patellar ligament to trochlear distance, and flattened lateral trochlear facet. • Understanding of the mechanical interaction and the anatomical development of the knee during adolescence provides further insight into the development of SHFP edema. Graphical Abstract

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.

Abstract 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.

Abstract The aim of this study was to investigate the reliability of panoramic ultrasound (US) imaging and agreement with magnetic resonance imaging (MRI) for assessing the average lumbar multifidus anatomical cross-sectional area between the lumbar vertebral bodies L3–L5 (i.e., LMF ACSAL3–L5). US and MRI scans of 20 male youth competitive alpine skiers were collected. To test the intra- and interrater reliability of US, transversal panoramic scans were analyzed on two different days by the same rater and the analysis of the first day was compared with the analysis of a second rater. To examine the agreement between US and MRI, Bland–Altman analysis was performed. Intrarater reliability was excellent, and interrater reliability was weak to good for both sides. The bias between MRI and US was − 0.19 ± 0.90 cm2 (2.68 ± 12.30%) for the left side and − 0.04 ± 0.98 cm2 (− 1.11 ± 12.93%) for the right side (i.e., for both sides US slightly overestimated LMF ACSAL3–L5 on average). The limits of agreement were − 1.95 to 1.57 cm2 (− 26.70 to 21.30%) for the left side and − 1.95 to 1.88 cm2 (− 26.46 to 24.24%) for the right side. Panoramic US imaging may be considered a method with excellent intrarater and weak to good interrater reliability for assessing LMF ACSAL3–L5. Comparison with MRI showed large individual differences in some cases, but an acceptable bias between the two imaging modalities.

To explore warm-up and activation (W&A) practices in high-performance snowsports to describe their importance, application and potential improvements based on the perspectives of elite-level athletes and staff members. Qualitative study consisting of semistructured interviews with 13 international elite-level athletes, on-snow coaches, strength and conditioning coaches, sports physiotherapists and sports psychologists from different snowsports and subdisciplines: alpine skiing, freestyle skiing (park and pipe, aerials, moguls) and snowboarding (park and pipe, snowboard cross). The interviews were transcribed verbatim and analysed based on the principles of grounded theory. The main themes raised by the participants were (1) the importance of readiness for sports participation as the motive for W&A, (2) how readiness is reached with a structured W&A routine and (3) the different athlete-specific, task-specific and environmental-specific factors for optimal W&A. Athletes and staff members considered W&A an essential measure to get physically and mentally ready for sports participation. Being ready was described as a key factor for performance and injury prevention. For these athletes, adherence to W&A was the result of a process of experiencing the beneficial effects of W&A and learning from sustaining one or more injuries. Broad implementation of basic physical and mental W&A at the youth level was considered an important measure to increase the overall adoption of W&A as an inherent part of training and competition. At the elite level, W&A is performed to reach athletes’ mental and physical readiness for performance enhancement and injury prevention. W&A is acknowledged as a complex and dynamic programme and is typically adapted to sport-specific demands, injury risks, environmental circumstances and individual needs and preferences. Overall, this study provides valuable contextual insights into the complexity of W&A and the factors that need to be considered to make sport-specific recommendations.

Introduction Patellar tendinopathy is frequent in adolescent athletes and particularly accentuated in competitive alpine skiers (Fröhlich et al., 2020). Tendinopathies are characterized by long disease histories, and whether they can be healed completely is an open question (Kettunen et al., 2002). Three-dimensional (3D) shear wave elastography (SWE) has proven valuable in the early detection of tendinopathies (Götschi et al., 2023). The aims of this study were to (1) describe the longitudinal progression of patellar tendon complaint prevalence in competitive alpine skiers during adolescence, (2) compare the SWV patterns of skiers that were symptomatic four years ago with those with no history of patellar tendon complaints and (3) analyse whether shear wave velocity (SWV) average values correlate with SWV coefficient of variation (CV). Methods Forty-seven subjects were analysed in this 4-year follow-up study regarding their patellar tendon complaints and SWV patterns. Symptomatic and asymptomatic skiers were identified by clinical examinations including the criteria of pain sensation under loading and palpation-induced pain. SWV was determined by ultrasound-based 3D SWE. Prevalence differences were assessed using Pearson’s χ2 tests. Group differences in the SWV patterns were analysed using unpaired sample t tests. Correlations between SWV average and CV values were analysed by means of Pearson’s correlation coefficient. Results With proceeding adolescence, the prevalence of patellar tendon complaints significantly decreased from 29.8% at baseline assessment (13-16 years) to 12.7% at follow-up assessment (Pearson’s χ2 = 9.429; p = 0.002). Those skiers who were symptomatic at baseline but asymptomatic at the follow-up still had lower average SWV values and higher CVs than asymptomatic skiers with no history of patellar tendon complaints (p = 0.054 and p = 0.011, respectively). Furthermore, there was a significant negative correlation between the tendon SWV average values and their CVs (R = -0.55; p < 0.001). Discussion/Conclusion Despite the decreasing prevalence of patellar tendon complaints in youth competitive alpine skiers after their growth spurt, structural abnormalities appear to remain in asymptomatic subjects with a previous history of patellar tendinopathy, indicating potential long-term implications for mechanical tendon proprieties. The SWV average and CV values were negatively correlated, which underlines our hypothesis that a low SWV is associated with a high CV. This altogether may reflect the degenerative processes in patellar tendons affected by complaints in the early stages of a sports career. References Fröhlich, S., Peterhans, L., Stern, C., Frey, W. O., Sutter, R., & Spörri, J. (2020). Remarkably high prevalence of overuse-related knee complaints and MRI abnormalities in youth competitive alpine skiers: A descriptive investigation in 108 athletes aged 13-15 years. BMJ Open Sport & Exercice Medicine, 6(1), Aticle e000738. https://doi.org/10.1136/bmjsem-2020-000738 Götschi, T., Franchi, M. V., Schulz, N., Fröhlich, S., Frey, W. O., Snedeker, J. G., & Spörri, J. (2023). Altered regional 3D shear wave velocity patterns in youth competitive alpine skiers suffering from patellar tendon complaints – A prospective case–control study. European Journal of Sport Science, 23(6), 1068-1076. https://doi.org/10.1080/17461391.2022.2088404 Kettunen, J. A., Kvist, M., Alanen, E., & Kujala, U. M. (2002). Long-term prognosis for jumper’s knee in male athletes. A prospective follow-up study. The American Journal of Sports Medicine, 30(5), 689-692. https://doi.org/10.1177/03635465020300051001

Introduction Lower limb muscle strength is an important predictor of sports performance, injury risk and frailty in ageing. The strength of a muscle is determined by its geometry and neuronal factors. Muscle geometry can be subdivided into architecture and morphology. Muscle morphology describes shape characteristics such as anatomical cross-sectional area (ACSA), thickness or volume (Maden-Wilkinson et al., 2021). Muscle architecture is determined by muscle fascicle length and the insertion angle of the muscle fascicles in the aponeuroses and describes the orientation of the muscle fibers relative to their force generation axis (Lieber & Friden, 2000). Muscle geometry is associated to physical performance and strength in humans (Maden-Wilkinson et al., 2021; Werkhausen et al., 2022) and is therefore a main research interest. A cost-effective and participant friendly method to validly and reliably assess muscle geometry is ultrasonography. However, a major limitation of ultrasonography is the subjectivity of image acquisition and the time-consuming image analysis (Ritsche et al., 2021; Ritsche, Wirth, et al., 2022; Ritsche et al., 2023). Moreover, image characteristics are massively influenced by the ultrasonography device used (Ritsche, Schmid, et al., 2022) as well as the muscle region scanned (Monte & Franchi, 2023). This poses constraints on the generalizability of existing automated image analysis approaches. The goal of this series of studies is therefore to optimize the ultrasonography acquisition and data analysis procedures by developing open-source software packages. Secondly, we aim to apply these methods in a sports performance context and describe the relevance of muscle geometry. Methods To streamline the time-consuming and subjective process of image analysis, we developed open-source and user-friendly software packages for muscle geometry analysis in lower limb muscles. We developed a semi-automated algorithm “ACSAuto” for assisted analysis of muscle ACSA using common image filtering processes (Ritsche et al., 2021). Given the limited generalizability and required user input of this approach, we developed two fully automated software applications, “DeepACSA” and “DL_Track_US”, using convolutional neural networks for more time efficient and robust analysis of lower limb muscle geometry (Ritsche et al., 2023; Ritsche, Wirth, et al., 2022; Ritsche et al., in press). We compared the predictions in an unseen test set to the current state-of-the-art, manual analysis, in order to evaluate the performance of our algorithms. To broaden the application of ultrasonography for evaluating muscle geometry in a sports context, we investigated the validity of a low-cost mobile ultrasonography device compared to a high-end counterpart in assessing various muscle architectural parameters in healthy adults (Ritsche, Schmid, et al., 2022).The mobile ultrasonography setup consisted of a smartphone and a portable probe, enabling practitioners high flexibility in the assessment of muscle architecture. We further investigated the link between muscle geometry and performance among soccer players. In one study, we focused on the m. biceps femoris long head in under-13 to under-15 youth players, assessing architecture and morphology at the mid-muscle point and correlating these with their sprint times and maximum velocity (Ritsche et al., 2020). In a further study, we analyzed the mm. vastus lateralis and rectus femoris in both youth and adult players of both sexes, evaluating muscle geometry at various muscle lengths alongside their knee extension strength during isometric and isokinetic conditions (Ritsche et al., in preparation and under review). Results Both ACSAuto and DeepACSA showed high comparability in assessing lower limb muscle ACSA with standard error of measurement lower than one cm2 (SEM ranging from 1.2 to 9.5%; Ritsche et al., 2021; Ritsche, Wirth, et al., 2022). Moreover, DeepACSA provided fast and objective analysis comparable to manual segmentation with no supervision of the analysis process needed. The time needed for analysis was reduced by a factor of 10. DL_Track_US demonstrated high comparability to manual muscle architecture analysis of images and videos, i.e. dynamic situations, (Ritsche et al., 2023; Ritsche et al., in press) and a reduction in the duration of analysis by a factor of 100. The mobile ultrasonography system showed a high degree of reliability and comparability only for m. gastrocnemius medialis architecture assessment, with a standard error of measurement lower than 10% for all architectural parameters (Ritsche, Schmid, et al., 2022). Thus, its reliability and comparability depended on the muscle assessed. We observed relevant correlations between muscle ACSA in young and adult male soccer players as well as in female soccer players and performance (Ritsche et al., 2020; Ritsche et al., unpublished). Moreover, we observed changes in muscle geometry with age and differences between males and females. Specifically, m. biceps femoris ACSA was strongly correlated with 30m sprint times and maximal velocity (r = -0.61 and r = 0.61, respectively), highlighting its importance in athletic performance (Ritsche et al., 2020). M. vastus lateralis ACSA at 50% of muscle length was most frequently related to knee extension strength (r = 0.40 - 0.53), which was observed in both sexes and across several age groups of male soccer players (Ritsche et al., in preparation and under review). Relevant correlations occurred more frequently in older age groups and higher knee extension velocities. Interestingly, we did not observe relevant correlations between muscle architecture and performance in the mm. biceps femoris and vastus lateralis. Discussion/Conclusion The results of this series studies so far led to three main insights. Firstly, the development of the “ACSAuto”, “DeepACSA” and “DL_Track_US” tools, utilizing semi-automated and fully automated analysis techniques applying deep learning algorithms, marked another step forward in overcoming the subjectivity and time consuming image evaluation. In a user-friendly way, these tools enable reproducible and objective analyses of muscle geometry in ultrasonography images. Secondly, with technological advancements, assessing muscle geometry with ultrasonography is possible using a smartphone and a probe, and often gives comparable results to high-end devices (Ritsche, Schmid, et al., 2022). This allows for a broader and more versatile application of muscle geometry assessment. However, our results highlight the need for a selective approach based on the muscle group being assessed and technical improvements of existing devices. Lastly, our findings across several investigations reveal a relevant positive correlation between muscle ACSA and performance metrics such as sprint times and knee extension strength (Ritsche et al., 2020; Ritsche et al., unpublished), corroborating previous research (Maden-Wilkinson et al., 2021; Monte & Franchi, 2023). The relationship was more pronounced in older age groups, suggesting that muscle geometry's influence on performance may amplify with athletic maturity. Apart from that, we observed the relationship in the m. vastus lateralis to be region- and contraction velocity-dependent. In agreement with Werkhausen et al. (2022), no relation of muscle architecture with strength when assessed in a static resting position was observed. This highlights the need for a potential shift towards assessing changes in muscle geometry during contraction rather than in static situations when evaluating the relation between muscle geometry and performance. Finally, remaining challenges include the comparability of muscle geometry assessment in the literature, the analysis methods used and the low generalizability of available automated analysis approaches (ours included). There is a clear need for methodological consensus on the assessment of muscle geometry when using ultrasonography, and more versatile analysis approaches are needed to enable an easy, generalizable and reproducible analysis of images and videos. Therefore, future works should target to establish assessment and analysis guidelines of muscle geometry in ultrasonography images to increase the comparability and reproducibility of results. Moreover, assessing changes in muscle geometry during contraction rather than during rest should be focused. References Lieber, R. L., & Friden, J. (2000). Functional and clinical significance of skeletal muscle architecture. Muscle Nerve, 23(11), 1647–1666. https://doi.org/10.1002/1097-4598(200011)23:11%3C1647::aid-mus1%3E3.0.co;2-m Maden-Wilkinson, T. M., Balshaw, T. G., Massey, G. J., & Folland, J. P. (2021). Muscle architecture and morphology as determinants of explosive strength. European Journal of Applied Physiology, 121(4), 1099–1110. https://doi.org/10.1007/s00421-020-04585-1 Monte, A., & Franchi, M. V. (2023). Regional muscle features and their association with knee extensors force production at a single joint angle. European Journal of Applied Physiology, 123, 2239-2248. https://doi.org/10.1007/s00421-023-05237-w Ritsche, P., Bernhard, T., Roth, R., Lichtenstein, E., Keller, M., Zingg, S., Franchi, M. V., & Faude, O. (2020). M. biceps femoris long head architecture and sprint ability in youth soccer players. International Journal of Sports Physiology and Performance, 16(11), 1616-1624. https://doi.org/10.1123/ijspp.2020-0726 Ritsche, P., Schmid, R., Franchi, M. V., & Faude, O. (2022). Agreement and reliability of lower limb muscle architecture measurements using a portable ultrasound device. Frontiers in Physiology, 13, Article 981862. https://doi.org/10.3389/fphys.2022.981862 Ritsche, P., Seynnes, O., & Cronin, N. (2023). DL_Track_US: A python package to analyse muscleultrasonography images. Journal of Open Source Software, 8(85), Article 5206. https://doi.org/10.21105/joss.05206 Ritsche, P., Wirth, P., Cronin, N. J., Sarto, F., Narici, M. V., Faude, O., & Franchi, M. V. (2022). DeepACSA: Automatic segmentation of cross-sectional area in ultrasound images of lower limb muscles using deep learning. Medicine & Science in Sports & Exercise, 54(12), 2188-2195. https://doi.org/10.1249/MSS.0000000000003010 Ritsche, P., Wirth, P., Franchi, M. V., & Faude, O. (2021). ACSAuto-semi-automatic assessment of human vastus lateralis and rectus femoris cross-sectional area in ultrasound images. Scientific Reports, 11, Article 13042. https://doi.org/10.1038/s41598-021-92387-6 Werkhausen, A., Gløersen, Ø., Nordez, A., Paulsen, G., Bojsen-Møller, J., & Seynnes, O. R. (2022). Rate of force development relationships to muscle architecture and contractile behavior in the human vastus lateralis. Scientific Reports, 12, Article 21816. https://doi.org/10.1038/s41598-022-26379-5

Introduction: The mechanical properties of skeletal muscle are indicative of its capacity to perform physical work, state of disease, or risk of injury. Ultrasound shear wave elastography conducts a quantitative analysis of a tissue’s shear stiffness, but current implementations only provide two-dimensional measurements with limited spatial extent. We propose and assess a framework to overcome this inherent limitation by acquiring numerous and contiguous measurements while tracking the probe position to create a volumetric scan of the muscle. This volume reconstruction is then mapped into a parameterized representation in reference to geometric and anatomical properties of the muscle. Such an approach allows to quantify regional differences in muscle stiffness to be identified across the entire muscle volume assessed, which could be linked to functional implications.Methods: We performed shear wave elastography measurements on the vastus lateralis (VL) and the biceps femoris long head (BFlh) muscle of 16 healthy volunteers. We assessed test-retest reliability, explored the potential of the proposed framework in aggregating measurements of multiple subjects, and studied the acute effects of muscular contraction on the regional shear wave velocity post-measured at rest.Results: The proposed approach yielded moderate to good reliability (ICC between 0.578 and 0.801). Aggregation of multiple subject measurements revealed considerable but consistent regional variations in shear wave velocity. As a result of muscle contraction, the shear wave velocity was elevated in various regions of the muscle; showing pre-to-post regional differences for the radial assessement of VL and longitudinally for BFlh. Post-contraction shear wave velocity was associated with maximum eccentric hamstring strength produced during six Nordic hamstring exercise repetitions.Discussion and Conclusion: The presented approach provides reliable, spatially resolved representations of skeletal muscle shear wave velocity and is capable of detecting changes in three-dimensional shear wave velocity patterns, such as those induced by muscle contraction. The observed systematic inter-subject variations in shear wave velocity throughout skeletal muscle additionally underline the necessity of accurate spatial referencing of measurements. Short high-effort exercise bouts increase muscle shear wave velocity. Further studies should investigate the potential of shear wave elastography in predicting the muscle’s capacity to perform work.

Objectives This study investigated the prevalence and severity of health problems in national-level female soccer players with respect to league and seasonality.Methods In a prospective cohort study, 46 female soccer players aged 22.8±3.9 years playing in the three highest leagues in Switzerland were surveyed biweekly using the Oslo Sports Trauma Research Centre health problem (OSTRC-H) questionnaire. All definitions and measures followed the OSTRC-H-specific recommendations. The 6-month observation period included parts of the off-season and one half of the match season.Results The average 2-weekly health problem prevalence was 37.3% (illnesses: 8.8%; sudden onset injuries—both acute and repetitive mechanisms: 19.7%; repetitive gradual onset injuries: 12.4%) and 25.1% for substantial problems as defined in the OSTRC-H context (7.3%; 12.0% and 7.3%, respectively). The absolute injury rates amounted to 148 injuries per 100 players per half season, of which 96 injuries per 100 players per half season were substantial. Female players in the 2nd and 3rd highest national leagues showed more gradual onset injuries (p

Snow sports such as alpine skiing or snowboarding are associated with a high risk of injury and reinjury and are subject to a very special environment with specific rehabilitation challenges that must be addressed. Due to geographic decentralisation, seasonal climatic limitations, alternation of training in off-snow and on-snow settings and unique loading patterns of practising these sports, special rehabilitation structures and processes are required compared with other sports. In addition, returning to preinjury performance requires a high level of confidence and a resumption of risk-taking in demanding situations such as high-speed skiing and high-amplitude jumps. A biopsychosocial and interdisciplinary approach can be viewed as a holistic, athlete-centred approach that promotes interprofessional communication and collaboration. This is particularly central for managing the physical/biological, psychological and social demands of injury management for snow sports. It can help ensure that rehabilitation content is well coordinated and tailored to individual needs. This is because transitions between different rehabilitation phases and caring professionals are well aligned, and rehabilitation is understood not only as purely ‘physical recovery’ but also as ‘psychological recovery’ considering the snow sports-specific setting with specific social norms. Ultimately, this may improve the rehabilitation success of snow sports athletes.

In epidemiological studies related to winter sports, especially alpine skiing, an unresolved methodological challenge is the quantification of actual on-snow activity exposure. Such information would be relevant for reporting meaningful measures of injury incidence, which refers to the number of new injuries that occur in a given population and time period. Accordingly, accurate determination of the denominator, i.e., actual “activity exposure time”, is critical for injury surveillance and reporting. In this perspective article, we explore the question of whether wearable sensors in combination with mHealth applications are suitable tools to accurately quantify the periods in a ski day when the skier is physically skiing and not resting or using a mechanical means of transport. As a first proof of concept, we present exemplary data from a youth competitive alpine skier who wore his smartphone with embedded sensors on his body on several ski days during one winter season. We compared these data to self-reported estimates of ski exposure, as used in athletes' training diaries. In summary, quantifying on-snow activity exposure in alpine skiing using sensor data from smartphones is technically feasible. For example, the sensors could be used to track ski training sessions, estimate the actual time spent skiing, and even quantify the number of runs and turns made as long as the smartphone is worn. Such data could be very useful in determining actual exposure time in the context of injury surveillance and could prove valuable for effective stress management and injury prevention in athletes.

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 (5.37m with 95% CI [5.21, 5.53]) and male skiers (5.90m 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. [ABSTRACT FROM AUTHOR]

Background: During an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective. Methods: Eight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography of 4 relevant muscle groups, inertial measurement units to measure knee and hip angles, and pressure insoles to determine ground reaction forces. Results: Due to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL. Conclusion: Our example emphasizes that ski racers should not get up until they stop sliding. Remember: “When you're down, stay down.”

From a preventative perspective, leg axis and core stabilization capacities are important for soccer players and alpine skiers; however, due to different sport-specific demands, the role of laterality clearly differs and may result in functional long-term adaptations. The aims of this study are 1) to determine whether there are differences in leg axis and core stability between youth soccer players and alpine skiers and 2) between dominant and non-dominant sides, and 3) to explore the outcomes of applying common sport-specific asymmetry thresholds to these two distinct cohorts. Twenty-one highly trained/national-level soccer players (16.1 years, 95% CI: 15.6, 16.5) and 61 alpine skiers (15.7 years, 95% CI: 15.6, 15.8) participated in this study. Using a marker-based 3D motion capture system, dynamic knee valgus was quantified as the medial knee displacement (MKD) during drop jump landings, and core stability was quantified as the vertical displacement during deadbug bridging exercise (DBBdisplacement). For the analysis of sports and side differences, a repeated-measures multivariate analysis of variance was used. For the interpretation of laterality, coefficients of variation (CV) and common asymmetry thresholds were applied. There were no differences in MKD or DBBdisplacement between soccer players and skiers or between the dominant and non-dominant sides, but there was an interaction effect side*sports for both variables (MKD: p = 0.040, η2p = 0.052; DBBdisplacement: p = 0.025, η2p = 0.061). On average, MKD was larger on the non-dominant side and DBBdisplacement laterality on the dominant side in soccer players, whereas this pattern was reversed in alpine skiers. Despite similar absolute values and asymmetry magnitudes of dynamic knee valgus and deadbug bridging performance in youth soccer players and alpine skiers, the effect on the direction of laterality was opposite even though much less pronounced. This may imply that sport-specific demands and potential laterality advantages should be considered when dealing with asymmetries in athletes.

Objectives: In 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. Methods: We 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. Results: We 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. Conclusions: PCK 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.

Objectives To analyse the available evidence and identify gaps in current knowledge regarding physical activity volume and intensity and their effects on pregnancy outcomes in female athletes.Design Scoping review.Data sources A structured literature search of three electronic databases (Embase, PubMed and Web of Science) was conducted on 25 February 2022, and a rerun search was conducted on 8 September 2022.Eligibility criteria Studies were eligible if they contained information on the relevant population (ie, elite or competitive amateur female athletes), intervention/exposure (ie, minimum of 10 hours of sport per week) and fetal and maternal outcomes. Eligible comparators included female recreational athletes and pregnant non-exercisers.Risk of bias The risk of bias was evaluated with the National Institutes of Health (National Heart, Lung and Blood Institute) quality assessment tool.Results The results revealed a discrepancy between the number of original research papers and the number of reviews and recommendations derived from them. The identified studies focused primarily on pregnant recreational athletes. Sixteen clinical studies met the inclusion criteria. No adverse effects on maternal or fetal outcomes were reported. Only during performance tests involving acute intensive exercise with the mother exercising at more than 90% of her maximal heart rate did some fetuses experience decelerations in heart rate.Summary/conclusion A lack of high-quality studies and direct evidence on pregnant elite and competitive amateur female athletes is evident. Further prospective observational cohort studies are needed using new monitoring methods (eg, non-invasive, wireless monitoring systems) aiming to gain a broader understanding of the stress tolerance of pregnant athletes and fetuses during exercise. Following that, interventional studies with stress tests in laboratory settings should be conducted. Therefore, technology plays a decisive role in gaining new knowledge and providing evidence-based recommendations on this topic.PROSPERO registration number CRD42022309541.

ObjectivesLittle is known about the extent of video gaming among elite athletes, specifically under stressful conditions like those induced by the current COVID-19 pandemic. The aim of this study was to evaluate the intensity and extent of video gaming in the context of the COVID-19 pandemic, during which the usual daily routine of many athletes was disrupted.MethodsOverall, 203 elite athletes from Switzerland who participated in Olympic sports or in “International Olympic Committee”—approved disciplines were interviewed using an online questionnaire. They were questioned on their video game consumption during the first Swiss lockdown during the COVID-19 pandemic as well as on their athletic performance and economic circumstances. Additionally, mental and physical health were assessed by standardized questionnaires. From this questionnaire data, predictors of gaming time were evaluated using multivariable analysis.ResultsBefore the lockdown, 21% of the participating athletes played video games regularly. The average playing time was 15.8 h per month within the gamer group. During the first lockdown, 29% of athletes reported gaming regularly, and within the gamer group the average gaming time increased significantly, by 164%. The mental health burden showed significant differences between gamers and non-gamers regarding existential fears during the lockdown, the ability to cope with governmental measures due to COVID-19 and total sleeping time. However, there was no statistical difference in respect to standardized scales for depressive symptoms, sleep behavior, and anxiety. Higher video gaming time during the lockdown was significantly associated with male gender and previous gaming before the COVID-19 lockdown.ConclusionVideo gaming time increased significantly during the first lockdown. Whether video gaming among elite athletes hereby functions as an effective coping behavior remains to be shown and requires more research.

Lower extremity injuries are common in competitive alpine skiers, and the knee and lower leg are often affected. The hamstring muscles, especially the biceps femoris long head (BFlh), can stabilize the knee and the hip and may counteract various adverse loading patterns during typical mechanisms leading to severe lower extremity injuries. The aim of the present study was to describe BFlh morphology in youth competitive alpine skiers in relation to sex, age and biological maturation and to investigate its association with the occurrence of traumatic lower extremity injuries in the upcoming season. 95 youth skiers underwent anthropometric measurements, maturity offset estimations and ultrasound assessment, followed by 12-months prospective injury surveillance. Unpaired t tests showed that the two sexes did not differ in BFlh morphology, including fascicle length (Lf), pennation angle (PA), muscle thickness (MT) and average anatomical cross-sectional area (ACSAavg). In contrast, U16 skiers had longer fascicles than U15 skiers (9.5 ± 1.3 cm vs 8.9 ± 1.3 cm, p < 0.05). Linear regression analyses revealed that maturity offset was associated with Lf (R2 = 0.129, p < 0.001), MT (R2 = 0.244, p < 0.001) and ACSAavg (R2 = 0.065, p = 0.007). No association was found between maturity offset and PA (p = 0.524). According to a binary logistic regression analysis, ACSAavg was significantly associated with the occurrence of traumatic lower extremity injuries (Chi-square = 4.627, p = 0.031, RNagelkerke2 = 0.064, Cohen f = 0.07). The present study showed that BFlh morphology is age- and biological maturation-dependent and that BFlh ACSAavg can be considered a relevant modifiable variable associated with lower extremity injuries in youth competitive alpine skiers.

Patellar tendon (PT) complaints are frequent in competitive alpine skiers and such complaints are characterized by a long-lasting affection. Since PTs are subject to maturation up to 1-2 years after growth spurt, this early career stage may be decisive for the further course of complaints. The aim of this study was to investigate the evolution of PT complaints and shear wave velocity patterns among competitive alpine skiers during a 4-year post-growth spurt follow-up. The PT complaints and SWV patterns of forty-seven skiers were analysed at baseline (i.e., immediately after their peak height growth at 13-15 years of age) and were re-analysed at 4-year follow-up. The PTs were scanned via threedimensional SWE. Symptomatic skiers were identified based on pain sensation under loading and pressure-induced pain around the PT. The prevalence of PT complaints decreased from 29.8% at baseline to 12.8% at follow-up (Pearson's 2 = 9.429; p = 0.002). SWV decreased from the baseline assessment to the follow-up in the proximal and distal regions (p < 0.05). SWV coefficient of variation (CV) in the distal and mid-portion regions was greater at baseline than at follow-up (p < 0.05). At the follow-up assessment, compared to "healthy" skiers, "healed" skiers who recovered from PT complaints had lower SWVs in the proximal region (p = 0.020) and greater SWV CVs in the proximal region (p = 0.028). Moreover, symptomatic skiers had significantly greater SWV CVs in the mid-portion region than did "healthy" subjects with no history of PT complaints (p = 0.020). The average SWV was negatively correlated with the SWV (proximal: r = -0.74, p < 0.001; mid-portion: r = -0.37 p = 0.011; and distal: r = -0.58, p < 0.001). The occurrence of PT complaints decreased over a 4-year post-growth spurt follow-up. "Healed" skiers who were symptomatic at baseline had an even greater average decrease in the proximal and mid-portion SWV than "healthy" skiers with no history of PT complaints. This may lead to the hypothesis that PT complaints in adolescent skiers are not self-eliminating towards the end of adolescence, as at least structural irregularities appear to persist for several years after the onset of initial symptoms. Furthermore, "healed" and symptomatic tendons exhibited increased SWV variability, supporting the hypothesis that SWV CV may provide additional valuable information on the mechanical properties of PTs affected by overuse-related complaints. [ABSTRACT FROM AUTHOR]

Abstract In Super-G alpine ski racing mean speed is nearly as high as in Downhill. Hence, the energy dissipated in typical impact accidents is similar. However, unlike Downhill, on Super-G courses no training runs are performed. Accordingly, speed control through course design is a challenging but important task to ensure safety in Super-G. In four male World Cup alpine Super-G races, terrain shape, course setting and the mechanics of a high-level athlete skiing the course were measured with differential global navigation satellite systems (dGNSS). The effects of course setting on skier mechanics were analysed using a linear mixed effects model. To reduce speed by 0.5 m/s throughout a turn, the gate offset needs to be increased by + 51%. This change simultaneously leads to a decrease in minimal turn radius (− 19%), an increase in impulse (+ 27%) and an increase in maximal ground reaction force (+ 6%). In contrast, the same reduction in speed can also be achieved by a − 13% change in vertical gate distance, which also leads to a small reduction in minimal turn radius (− 4%) impulse (− 2%), and no change in maximal ground reaction force; i.e. fewer adverse side effects in terms of safety. It appears that shortening the vertical gate distance is a better and safer way to reduce speed in Super-G than increasing the gate offset.

Background: Sport climbing places high mechanical loads on fingers. In 2012, our research group demonstrated adaptations of climbers’ cortical bones with the presence of osteophytes compared to non-climbing controls.Objectives: 1) To investigate 10-year changes in cortical bone thickness, base osteophyte occurrence and radiological signs of osteoarthritis in the fingers of elite male sport climbers with more than 25 years of climbing history and 2) to compare cortical bone thickness, base osteophyte occurrence and radiological signs of osteoarthritis between male sport climbers and age-matched controls at the 10-year follow-up.Methods: All 31 elite sport climbers who participated in both the baseline and 10-year follow-up assessments (follow-up rate 100%) were examined by means of X-rays. Cortical bone thickness, presence of osteophytes and signs of osteoarthritis according to Kellgren-Lawrence were obtained and compared to the baseline values 10 years earlier and to age-matched controls at the follow-up (n = 15).Results: Significantly increased cortical bone thickness over the past 10 years was observed in climbers (mean absolute difference with 95% CI:0.98 mm (0.77 mm, 1.19 mm); p

Competitive alpine skiers are exposed to enormous forces acting on their bodies–particularly on the knee joint and hence the patellar tendon - during both the off-season preparation and in-season competition phases. However, factors influencing patellar tendon adaptation and regional pattern differences between alpine skiers and healthy controls are not yet fully understood, but are essential for deriving effective screening approaches and preventative countermeasures. Thirty elite competitive alpine skiers, all members of the Swiss Alpine Ski Team, and 38 healthy age-matched controls were recruited. A set of two-dimensional shear wave elastography measurements of the PT was acquired and projected into three-dimensional space yielding a volumetric representation of the shear wave velocity profile of the patellar tendon. Multivariate linear models served to quantify differences between the two cohorts and effects of other confounding variables with respect to regional shear wave velocity. A significant (p < 0.001) intergroup difference was found between skiers (mean ± SD = 10.4 ± 1.32 m/s) and controls (mean ± SD = 8.9 ± 1.59 m/s). A significant sex difference was found within skiers (p = 0.024), but no such difference was found in the control group (p = 0.842). Regional SWV pattern alterations between skiers and controls were found for the distal region when compared to the mid-portion (p = 0.023). Competitive alpine skiers exhibit higher SWV in all PT regions than healthy controls, potentially caused by long-term adaptations to heavy tendon loading. The presence of sex-specific differences in PT SWV in skiers but not in controls indicates that sex effects have load-dependent dimensions. Alterations in regional SWV patterns between skiers and controls suggest that patellar tendon adaptation is region specific. In addition to the implementation of 3D SWE, deeper insights into long-term tendon adaptation and normative values for the purpose of preventative screening are provided.

Background:Government restrictions during the first COVID-19 lockdown, such as the closure of gyms and fitness centers, drastically limited the training opportunities of bodybuilders and fitness athletes (BoFA) who rely on indoor training facilities. This provided a unique situation to investigate the effect of training limitations on the training patterns, training adaptive strategies and mental health of BoFAs.ObjectivesThe primary aim of this study was to investigate differences in the training patterns and the mental health of BoFA before and during the first COVID-19 lockdown. The secondary aim was to assess whether BoFA who exhibited features of muscle dysmorphia were affected differently from the group that did not.MethodsA cross-sectional study was conducted with 85 BoFAs by means of an online questionnaire asking about sports activity, intensity, subjective physical performance, and economic status, including primary or secondary occupations before (from memory) and during lockdown, current physical health problems and financial fears, symptoms of depression, sleep disorders, anxiety (trait and state), muscle dysmorphia, coping mechanisms and actions during the first lockdown in Switzerland.ResultsTraining patterns and mental health of BoFA were influenced by the COVID-19 pandemic and first lockdown. During lockdown, the physical activity on the BoFA dropped significantly from 2.3 ± 0.8 h per day to 1.6 ± 0.9 h per day (p < 0.001), the subjective training intensity decreased significantly from 85.7 ± 13.2% to 58.3 ± 28.3% (p < 0.001) and the subjective performance declined significantly from 83.4 ± 14.3% to 58.2 ± 27.8% (p < 0.001) of maximal performance. In comparison to those without risk for body dysmorphia, participants at risk rated their maximal performance significantly lower and scored significantly higher for depression, sleep disorders and anxiety.ConclusionThis study showed the significant changes on the training patterns of BoFA before and during the first COVID-19 lockdown and poor mental health scores of BoFA during the lockdown itself, with those at risk of muscle dysmorphia scoring statistically worse regarding mental health than those with no risk of muscle dysmorphia. To better understand the particularities of BoFA, further investigation is needed to understand their psychology and in particular the effect of training restrictions on it.

This study aimed 1) to assess the test-retest reliability of dynamic postural stability index (DPSI) assessments using a ski-specific jump protocol that consists of single-leg landings on a three-dimensional force plate after forward-performed double-leg drop jumps from a box over a hurdle (DJSLLs), 2) to provide reference values for female and male youth competitive alpine skiers; 3) to explore their changes in DPSI over 3 years during adolescence; and 4) to investigate potential associations of DPSI with age and biological maturation. Using three-dimensional force plates, 16 healthy subjects were tested on the same day (test-retest reliability experiment; five test-retest assessments of right leg landings), and 76 youth skiers aged 13–15 years were tested 3 times within 2 years (main experiment; average of two trials per leg each time). The test-retest reliability experiment revealed an ICC(3,1) and 95% CI of 0.86 [0.74, 0.94] for absolute DPSI assessment. The within-subject SEM of absolute DPSI was 16.30 N [13.66 N, 20.65 N], and the standardized typical error was moderate (0.39 [0.33, 0.50]). Both absolute and relative DPSI values were comparable between male and female youth competitive alpine skiers. The mean absolute DPSI in year 1 (195.7 ± 40.9 N), year 2 (196.5 ± 38.9 N) and year 3 (211.5 ± 41.3 N) continuously increased (i.e., worsened) (p < 0.001). Mean relative, i.e. body weight force normalized, DPSI values significantly decreased, i.e., improved, from year 1 to 2 (0.42 ± 0.01 vs. 0.36 ± 0.004; p < 0.001) and year 1 to 3 (0.42 ± 0.01 vs. 0.36 ± 0.01; p < 0.001). Absolute DPSI correlated with age and biological maturation, while no such correlations were found for relative DPSI values. Our findings suggest that DPSI is a reliable and sensitive measure of dynamic postural control during DJSLLs and that relative DPSI improves annually in competitive youth skiers when accounting for body weight. Future work should consider biological maturation testing during the growth spurt, and normalizing to body weight force could be a possible solution.

Evidence-based injury prevention programmes for youth competitive alpine skiers are widely absent. The aims of this controlled 12-month experimental study were to introduce a novel injury prevention programme targeted to the injury patterns of youth skiers, called ISPAInt, and to compare the differences in injury occurrence between an intervention group (IG) additionally performing the ISPAInt programme and an independent, historical control group (CG) following their regular training routines. None of the skiers of the CG were part of the IG and vice versa. The study was directly conducted within the real-world youth development structures of skiers competing at the under 16 years (U16) level in Switzerland. Seventy-one skiers (aged 14.4 ± 0.3 years) assigned to the IG were compared to 58 age- and gender-matched controls. The IG was offered the ISPAInt programme with the recommendation to perform it at least once per week. Skiers’ adherence to this recommendation was surveyed but not enforced. Injuries were recorded using the Oslo Sports Trauma Research Centre Questionnaire. Primary outcomes were the absolute injury rates (number of injuries/100 athletes per season) and epidemiological incidence proportion (number of injured athletes/100 athletes per season). The secondary outcome was the average 2-weekly prevalence of traumatic knee, knee overuse, and lower back overuse injuries. There were lower absolute rates of all traumatic injuries [rate/risk difference, RD: −57.1 (−98.1, −16.0); rate/risk ratio, RR: 0.665 (0.485, 0.884)] and overuse injuries [RD: −35.9 (−71.0, −0.7); RR: 0.699 (0.493, 0.989)] in the IG than in the CG. Likewise, the epidemiological incidence proportion for all overuse injuries was smaller in the IG [RD: −28.4 (−44.8, −12.0); RR: 0.598 (0.435, 0.822)], while the proportion of skiers suffering from traumatic injuries did not significantly differ between the groups. Notably, the IG particularity differed from the CG in the average 2-weekly prevalence of knee trauma, knee overuse, and lower back overuse complaints, three of the major injury-related hot spots in youth skiers. Based on these promising results, the ISPAInt programme may have great potential to prevent injuries in youth competitive alpine skiers, and the underlying exercises should be considered complementary training content at the U16 level.

BackgroundThe COVID-19 pandemic and associated restrictions have led to abrupt changes in the lives of elite athletes.ObjectivesThe objective of this prospective cohort study was to examine training load, subjective sports performance, physical and mental health among Swiss elite athletes during a 6-month follow-up period starting with the first Swiss lockdown.MethodsSwiss elite athletes (n = 203) participated in a repeated online survey evaluating health, training, and performance related metrics. After the first assessment during the first lockdown between April and May 2020, there were monthly follow-ups over 6 months.ResultsOut of 203 athletes completing the first survey during the first lockdown, 73 athletes (36%) completed all assessments during the entire 6-month follow-up period. Sports performance and training load decreased during the first lockdown and increased again at the beginning of the second lockdown in October 2020, while symptoms of depression and financial fears showed only a transient increase during the first lockdown. Self-reported injuries and illnesses did not change significantly at any timepoint in the study. Stricter COVID-19 restrictions, as measured by the Government Stringency Index (GSI), were associated with reduced subjective sports performance, as well as lower training intensity, increased financial fears, poorer coping with restrictions, and more depressive symptoms, as measured by the 9-item module of the Patient Health Questionnaire-9 (PHQ-9).ConclusionThis study revealed a negative impact of the COVID-19 restrictions on sports performance, training load and mental health among Swiss elite athletes, while the rate of self-reported injuries and illnesses remained unaffected.

Objectives: During the COVID-19 pandemic, increased patterns of substance use have been reported in the general population. However, whether this also applies to athletes is not yet clear. This study aimed to detect changes in alcohol consumption and cannabis use in elite athletes and bodybuilders during the first COVID-19 lockdown in Switzerland.Methods: Between April 25 and May 25, 2020, a cross-sectional online survey was conducted among bodybuilders and Swiss elite athletes who were active in Olympic sports and disciplines approved by the International Olympic Committee (IOC) on at least the national level. The collected data included information on alcohol and cannabis use during the last month (lockdown) and in the year before COVID-19 lockdown (pre-lockdown), daily training times, existential fears on a scale from 1 to 100, Patient Health Questionnaire-9 for depression (PHQ-9), Insomnia Severity Index (ISI), and State-Trait Anxiety Inventory (STAI).Results:N = 275 athletes (elite athletes: n = 193; bodybuilders: n = 82) was included in this study. Both pre-lockdown and during lockdown, more bodybuilders used cannabis (both time points: p < 0.001) than elite athletes, and more elite athletes drank alcohol (pre-lockdown: p = 0.005, lockdown: p = 0.002) compared to bodybuilders. During lockdown, fewer athletes drank alcohol compared to before, but those who continued drinking did so on more days per week (p < 0.001, Eta2 = 0.13). Elite athletes were more likely to increase their drinking with 17.7 vs. 8.2% in bodybuilders. When compared to pre-lockdown measures, the number of athletes using cannabis did not change during lockdown. Only three of 203 elite athletes reported using cannabis during lockdown; this contrasts with 16 of 85 bodybuilders. In a multivariate regression model, existential fears and a lower ISI score were significant predictors for increased alcohol consumption during the lockdown in the entire sample. In a model based on elite athletes only, male sex and a lower ISI score predicted increased alcohol consumption. In a bodybuilder-based model, predictors of increased alcohol consumption were existential fears and trait anxiety.Conclusion: We suggest identifying athletes who are at risk for increased alcohol and cannabis use; we suggest this to be able to professionally support them during stressful times, such as the COVID-19 pandemic.

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 risk factors since then and (3) to compile a list with countermeasure suggestions.Methods A sample of 532 expert stakeholders (athletes, coaches, team medical staff, Ski Racing Suppliers (SRS) and International Ski Federation (FIS) representatives) from the World Cup (WC), European Cup (EC) and FIS-race level participated in a cross-sectional online survey. Experts were asked to name those risk factors with the highest believed impact on injury risk and rank them according to their current priority from a predefined list. In addition, experts were encouraged to name additional (not listed) risk factors and to suggest countermeasures.Results Regardless of stakeholder role and competition level, snow-related factors appeared to have the highest perceived priority. However, WC athletes’ and coaches’ perceptions were also related to equipment, while at the EC and FIS-race level fatigue and physical fitness-related factors were considered important. Athletes’ perceptions were largely in agreement with SRS (ie, snow-related and equipment-related factors). At the same time, while coaches, team medical staff and FIS representatives additionally emphasised fatigue and physical fitness-related factors.Conclusion Experts’ perceptions on key injury risk factors in alpine ski racing depend on the stakeholder role and differ between the competition levels. Thus, to develop effective prevention measures and to successfully implement them, all relevant stakeholders should be given a voice, and prevention efforts should be targeted to the specific level.

The aim of the study was to (1) assess the within-session reliability of a unilateral isometric hex bar pull (UIHBP) maximal voluntary contraction (MVC) test and, (2) determine unilateral isometric absolute peak force (PFabs) and relative peak force (PF) values in freeski athletes. Twenty-one male and eight female academy to national team freeskiers performed the novel UIHBP MVC task on a force plate and PFabs and relative PF were assessed (1000 Hz). Within-session measures of PFabs offered high reliability on left and right limbs for males (ICC = 0.91–0.94, CV = 2.6–2.2%) and females (ICC = 0.94–0.94, CV = 1.4–1.6%), while relative PF measures showed good to high reliability in both left and right limbs for males (ICC = 0.8–0.84, CV = 2.6–2.2%) and females (ICC = 0.92–0.90, CV = 1.4–1.7%). We observed significantly lower PFabs (p < 0.001) and relative PF (p < 0.001) in females compared to males. No statistical difference was found between left and right limbs in males and females in PFabs (p = 0.98) and relative PF measures (p = 0.93). The UIHBP MVC test appears to be a reliable method for assessing PFabs and relative PF in male and female freeski athletes.