Introduction: Over the years, advances in alpine ski equipment such as helmets, bindings, skis and boots have resulted in risk reduction, remodelling of injury patterns and mechanisms. Skiers’ ...injuries are currently about 1 to 5 per 1000 days spent in the snow per athlete. The most common area of the injury is the knee, especially ACL and MCL.
Purpose of the work: The purpose of the work is analysis of literature on mechanism of knee ligaments injury and potential prevention intervention in alpine skiing.
Methods and materials: The present study was based on available data collected in the PubMed and Google Scholar database. The study was conducted by reviewing keywords such as: “alpine skiing”, “ski bindings”, “alpine skiing injuries”, “ACL”.
Results: Taking into consideration less advanced skiers, we can distinguish three types of injury mechanism: valgus-external rotation sequence, boot-induced anterior drawer mechanism and phantom-foot mechanism. Three mechanisms have been described for professional skiers: slip-catch, landing back-weighted and dynamic snowplow. Female skiers have a higher risk of ACl injury than male skiers.
Conclusion: Most of the described injury mechanisms are linked with no releasing of bindings. The future injury prevention should concentrate on injury mechanisms using electronic sensors placed at skiers equipment. New micro-electronic technologies can help create mechatronic ski bindings.
•A mathematical model is proposed to simulate the behaviors of skiers competing for the championship.•A novel optimization algorithm is proposed using the mathematical model.•The proposed alpine ...skiing optimization (ASO) algorithm is tested on twenty-three unconstrained benchmark functions and four engineering design problems.•The results indicate that ASO can be used as a state-of-the-art optimization algorithm to solve engineering optimization problems.•ASO is applied to ensure the parameter of an auto drum fashioned brake. The braking efficiency factor can be improved 28.446% compared with the initial design. Results reveal that ASO is appreciated for complex engineering optimization problem due to its high efficiency, strong reliability and robust exploration performances.
A novel swarm intelligence optimization algorithm is proposed, which is named alpine skiing optimization (ASO). The main inspiration of the ASO originated from the behaviors of skiers competing for the championship. In the ASO, physical stamina and sprint are two essential factors for skiers to win the tournament, which are similar to the two stages of exploration and exploitation. The skiers revealed the behaviour of winning the tournament according to the static sliding and dynamic sliding. This work simulates this behaviour from a mathematical perspective and develops the ASO algorithm. The performance of the ASO algorithm is investigated, through a comparison with many competitive optimization algorithms and four constrained engineering problems. The statistical results validate that the ASO can provide competitive results compared to other state-of-the-art optimization algorithms. Furthermore, ASO is applied to optimize the parameter of an auto drum fashioned brake engineering problem. The objective function is chosen to maximize the braking efficiency coefficient. Results show that the braking efficiency factor is improved by 28.446% compared with the initial design.
Over the last 20 years a number of studies have been published using progressive eccentric exercise protocols on motorized ergometers or similar devices that allow for controlled application of ...eccentric loads. Exercise protocols ramp eccentric loads over an initial 3 weeks period in order to prevent muscle damage and delayed onset muscle soreness. Final training loads reach 400-500 W in rehabilitative settings and over 1200 W in elite athletes. Training is typically carried out three times per week for durations of 20-30 min. This type of training has been characterizes as moderate load eccentric exercise. It has also been denoted RENEW (Resistance Exercise via Negative Eccentric Work by LaStayo et al., 2014). It is distinct from plyometric exercises (i.e., drop jumps) that impose muscle loads of several thousand Watts on muscles and tendons. It is also distinct from eccentric overload training whereby loads in a conventional strength training setting are increased in the eccentric phase of the movement to match concentric loads. Moderate load eccentric exercise (or RENEW) has been shown to be similarly effective as conventional strength training in increasing muscle strength and muscle volume. However, as carried out at higher angular velocities of joint movement, it reduces joint loads. A hallmark of moderate load eccentric exercise is the fact that the energy requirements are typically 4-fold smaller than in concentric exercise of the same load. This makes moderate load eccentric exercise training the tool of choice in medical conditions with limitations in muscle energy supply. The use and effectiveness of moderate load eccentric exercise has been demonstrated mostly in small scale studies for cardiorespiratory conditions, sarcopenia of old age, cancer, diabetes type 2, and neurological conditions. It has also been used effectively in the prevention and rehabilitation of injuries of the locomotor system in particular the rehabilitation after anterior cruciate ligament surgery.
Two techniques facilitate the transition in an alpine ski turn, extension (EXT) and flexion (FLEX). The purpose of this study is to compare NIRS, EMG, and RPE responses between EXT and FLEX in expert ...level skiers.
24 Professional Ski Instructors of America Level III alpine ski instructors, examiners, and National Demonstration Team members completed one standardized run each of EXT and FLEX. A turn cycle, made of a right and left turn, was divided into four Phases.
NIRS assessed HbO2 desaturation in the rectus femoris (RF) and vastus lateralis (VL). EMG was collected from the RF, VL, and gluteus medius (GM). Rating of Perceived Exertion (RPE, 0–10) assessed subjective exertion.
FLEX resulted in greater HbO2 desaturation in RF (−77.9 ± 21% vs. −67.5 ± 23%, p < 0.001), VL (−69.8 ± 23.1% vs. −61.1 ± 24.6%, p < 0.001) and RPE (6.0 ± 2.3 vs. 5.2 ± 2.0, p < 0.001) compared to EXT. FLEX generally resulted in greater EMG activity in the steering and transition phases for RF and VL (p < 0.001) while EXT resulted in greater activity GM on the inside leg.
Caution should be exercised with recreational skiers as the FLEX transition resulted in significantly greater physiological stress compared to EXT. Localized hypoxia appears to be the focal point of this stress as HbO2 desaturation was ∼15% greater along with 15% greater RPE during FLEX. FLEX also produced greater EMG activity than EXT in the majority of the turn phases.
The boom of a semi submersible platform has large moment of inertia and high operating cost. How to effectively achieve the optimal solution of the boom to minimize the design and operation cost is a ...dynamic problem. In this study, a learning-imitation strategy-assisted alpine skiing optimization (LISASO) is proposed to find the optimal solution of the semi submersible platform boom. Firstly, the optimization model of the boom of the semi submersible platform is established. Secondly, the learning-imitation strategy (LIS) is implemented to improve the performance of the alpine skiing optimization (ASO). In LIS, the learning ability of individuals and the imitation of competitions are introduced to strengthen the association between individuals and the first individual. The performance of the LISASO is verified by three truss examples. The statistical results demonstrate that the LISASO is more competitive compared with other state-of-the-art optimization algorithms. Finally, the LISASO is applied to solve the optimal structural parameters of the boom. Results show that the energy consumption is reduced by 18.32% compared with the initial design.
•A learning-imitation strategy-assisted alpine skiing optimization (LISASO) is proposed.•An optimization algorithm is proposed using the mathematical model.•The optimization model of the boom of the semi submersible platform is established.•Superiorities of the LISASO compared with other state-of-the-art optimization algorithm is certified.•LISASO can reliably achieve optimal structural parameters of the boom.
The dynamic positioning system (DPS) is a complex mechatronic system consisting of multiple sub-disciplines. For such highly coupled sub-disciplines and sub-systems within the DPS, the conventional ...sequential design strategy cannot manage this interaction adequately and explicitly. Achieving the global optimal solution becomes challenging due to the discoordination between the structure and dynamic performance parameters. To address this challenge, a co-design strategy is explored by combining the structure and dynamic performance parameters based on a simultaneous dynamic optimization approach. To minimize the operating cost of the DPS, the radial basis function (RBF) model is extended to the constraint condition. The alpine skiing optimization (ASO) algorithm is applied to solve the multidisciplinary design optimization problem. The results indicate that the co-design strategy not only reduce the operating cost of the DPS but also achieve a smaller rolling response and yaw response.
•A novel optimization design strategy, namely co-design strategy, is proposed.•The multidisciplinary design optimization model of the dynamic positioning system (DPS) is established.•The co-design strategy is explored by combining the structure and dynamic performance parameters.•The alpine skiing optimization (ASO) algorithm is applied to solve the multidisciplinary design optimization problem.
We introduce a novel approach for computing gate-to-gate time automatically from audio recordings. In slalom skiing, gate-to-gate timing is a valuable metric for athletes and trainers, capturing the ...time elapsed between slalom gates. The availability of these measurements immediately after each run allows for prompt feedback. This study specifically concentrates on gate-to-gate timing in alpine slalom skating, serving as a foundational step towards its future application in slalom skiing. While existing methods for measuring gate-to-gate time vary in their feasibility, accuracy, and compliance with regulations, we propose a solution utilizing a convolutional neural network (CNN) to predict gate locations using the audio signals generated upon gate contact. By leveraging these predictions, we achieve fully automated computation of gate-to-gate timings. We conduct a comparative analysis between the CNN’s predictions and data obtained from an inertial measurement unit. Our findings reveal a strong predictive correlation between the two methods, with an R-squared value of 0.94 and a root mean squared error of 0.036. The majority of predictions demonstrate high accuracy, falling within a range of thousandths of a second. However, a few outliers negatively impact the overall performance. Notably, we observe no deterioration in predictive quality based on the distance between the camera and the gate. Finally, we delve into the challenges and limitations associated with our approach and provide a comprehensive discussion. To conclude, we outline potential avenues for future research and extensions of our methodology to the realm of slalom skiing.
The anterior cruciate ligament (ACL) has been extensively studied in those with alpine skiing injuries; however, less focus has been given to meniscal/chondral injuries in this population.
To perform ...a systematic review investigating the incidence of meniscal/chondral injuries in alpine skiers who have sustained an ACL injury.
MEDLINE, Scopus, manual journal searches.
Studies reporting rates of meniscal and/or chondral injuries in alpine skiers with an ACL tear were included. Techniques, revisions, non-alpine skiers, and studies lacking an association between skiing and ACL diagnosis were excluded.
Alpine skiers with a diagnosis of an ACL tear.
MINORS criteria.
Nine hundred fifty-eight studies were identified. Screening, removal of duplicates, and assessment for inclusion/exclusion criteria resulted in 12 level III/IV studies for review. A total of 1185 skiers with ACL injuries were included (209 elite and 976 recreational). Meniscal tears were present in 47.4% of the skiers, with an increased rate seen in elite versus recreational skiers (61.2% vs 43.2%). Elite skiers were more likely to have a combined medial/lateral meniscal injury and a lateral meniscal tear repair (69.8% vs 19.2% for the latter). There were no differences in medial meniscal tear treatment. Chondral injuries presented at a rate of 11.2% and were more common in elite versus recreational skiers (20.3% vs 5.3%).
Heterogenous nature of study types included; Did not include larger databases and was limited to alpine skiing studies only; demographics were not part of the analysis.
Approximately 47% of the alpine skiers with an ACL injury sustained a concomitant meniscal tear, with 11% having an associated chondral injury. Meniscal/chondral injuries are more common in elite skiers, and they are more likely to have their meniscus repaired.
Careful consideration of the accompanying pathology is warranted in alpine skiers who present with ACL injury.
PROSPERO: CRD42022373207.
Alpine skiing beginners are easily injured if they fail make the right decisions when faced with unexpected situations. Excellent decision-making requires extensive training, while alpine skiing ...training is limited by time and space. To address these issues, this paper combines VR and machine learning techniques to develop a high fidelity VR skiing decision-making training system based on HCPS framework. The aim is to train beginner skiers in decision-making by creating automated and repeatable virtual scenarios. Firstly, physical world (ski resort environment, and user motions) was mapped into the VR world using the HCPS framework. Afterwards, the user’s decision motions were made based on the scenarios provided, while being identified through an improved SVM (94.5% accuracy). The motion recognition results were fed into the expert system to assess the feasibility of the decision-making. Finally, the feasibility of the system was assessed with a combination of subjective and objective approaches. The results showed that the VR system significantly improved the participants’ skiing decision-making ability and speed compared to traditional 2D video training. The high fidelity environment reduced participants’ motion sickness symptoms and resulted in a better sensory experience. In addition, participants were more focused in the high fidelity environment. Overall, these results demonstrated the construct validity of the virtual ski decision-making training system. This study changes the traditional training method to create an immersive training environment, and provides an effective avenue for the development of sports training.
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•Designs processes and algorithmic models for virtual ski decision systems are presented.•Interaction between user and system via IMU and EEG signals.•The feasibility of the system is assessed through a combination of subjective and objective methods.•Voting classifier achieves higher action recognition rate.•VR training system improves decision-making skills and speed.
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