Since 2000 the Zentrum f¨ur Mathematik in Bensheim (ZFM) and the Technical University Darmstadt (TUDa) have organized an annual autumn school for mathematically highly talented pupils in their last ...year of school. For one week, the participants work in groups on application problems, which first need to be transformed into mathematics and then be solved by mathematical analyzation and numerical approximation and implementation on a computer. Finally, the results are presented. The problems are very realistic. Only minor details may be skipped, to make the problem easier to handle and to focus on the main issue at hand, but only if they do not affect the basic result. For some of the problems there exist similar, but much simpler, counterparts that can be solved in a shorter time period even in a usual school setting. Solving those simple problems opens the outlook to the hard problems if they are mentioned before. This paper examines two applications that led to mathematical problems from analysis and geometry.
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 (
< 0.05). Similarly, the contribution of anaerobic energy system at each speed showed significant improvement (
< 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.
The major research objective of the paper is to identify the essence of international sporting events, whose network nature is related to organizational links between cities, sports associations, the ...media, sponsors and other stakeholders. The analysis is based on the example of a cyclical event - the Four Hills Tournament. The stakeholder analysis was carried out and a model of network management of the relationship and organization of the sporting event was indicated. The history of the Tournament was also discussed in conjunction with the marketing, organizational and technological trends that have changed over the years.
The development and innovation of biomechanical measurement methods provide a solution to the problems in ski jumping research. At present, research on ski jumping mostly focuses on the local ...technical characteristics of different phases, but studies on the technology transition process are less.
This study aims to evaluate a measurement system (i.e. the merging of 2D video recording, inertial measurement unit and wireless pressure insole) that can capture a wide range of sport performance and focus on the key transition technical characteristics.
The application validity of the Xsens motion capture system in ski jumping was verified under field conditions by comparing the lower limb joint angles of eight professional ski jumpers during the takeoff phase collected by different motion capture systems (Xsens and Simi high-speed camera). Subsequently, the key transition technical characteristics of eight ski jumpers were captured on the basis of the aforementioned measurement system.
Validation results indicated that the joint angle point-by-point curve during the takeoff phase was highly correlated and had excellent agreement (0.966 ≤ r ≤ 0.998, P < 0.001). Joint root-mean-square error (RMSE) differences between model calculations were 5.967° for hip, 6.856° for knee and 4.009° for ankle.
Compared with 2D video recording, the Xsens system shows excellent agreement to ski jumping. Furthermore, the established measurement system can effectively capture the key transition technical characteristics of athletes, particularly in the dynamic changes of straight turn into arc in inrun, the adjustment of body posture and ski movement during early flight and landing preparation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study aimed to examine the effects of individualized-load power training (IPT) versus traditional moderate-load power training (TPT) on strength, power, jump performance, and body composition in ...elite young Nordic athletes.
In a randomized crossover design, 10 young male athletes (ski jumpers, Nordic combined athletes) age 17.5 (0.6) years (biological maturity status: +3.5 y postpeak height velocity) who competed on a national or international level performed 5 weeks of IPT (4 × 5 repetitions at 49%-72% 1-repetiton maximum RM) and TPT (5 × 5 repetitions at 50%-60% 1-RM) in addition to their regular training. Testing before, between, and after both training blocks comprised the assessment of muscle strength (loaded back squat 3-RM), power (maximal loaded back squat power), jump performance (eg, drop-jump height, reactive strength index), and body composition (eg, skeletal muscle mass).
Significant, large-size main effects for time were found for muscle strength (P < .01; g = 2.7), reactive strength index (P = .03; g = 1.6), and drop-jump height (P = .02; g = 1.9) irrespective of the training condition (IPT, TPT). No significant time-by-condition interactions were observed. For measures of body composition, no significant main effects of condition and time or time-by-condition interactions were found.
Our findings demonstrate that short-term IPT and TPT at moderate loads in addition to regular training were equally effective in improving measures of muscle strength (loaded back squat 3-RM) and vertical-jump performance (reactive strength index, drop jump, and height) in young Nordic athletes.
There is a lack of reviews covering the topic of the parallel high prevalence of injuries in female winter sport elite athletes. We aimed to review the data on incidence and patterns of injuries in ...female athletes participating in official competitions of winter sports. We conducted a comprehensive literature search on epidemiological data and etiological information on alpine skiing, snowboarding, ski jumping and cross-country skiing. The most common location of injury was the knee among skiers and ski jumpers and the incidence of severe ACL events was 7.6 per 100 ski racers per season (95% CI 6.6 to 8.9) in female alpine skiers. Snowboarders and cross-country skiers were more affected in the ankle and the foot. The most common cause was contact trauma with stagnant objects. The injury risk factors include training volume, knee pre-injuries, the period of the season and the technical equipment. Females are at greater risk of suffering from overuse injuries during the competitive season, as opposed to male athletes who are more likely to suffer from traumatic injuries. Our findings can be used to inform coaches and athletes and to guide future injury prevention plans.
This study was designed to develop a computational fluid dynamics (CFD) method for unsteady analysis of a series of ski jump movements with attitude changes, and to analyse the aerodynamic ...characteristics of an expert jumper over the entire ski jump movement. Two ski jumpers participated in this study. A sensor-based motion capture suit was used to capture the jumper's posture during the actual ski jump. A three-dimensional computer graphics animation was created by superimposing the joint angles obtained from the motion measurements of the 3D shape of the athlete. The unsteady aerodynamic forces acting on the ski jumper, from the takeoff to the landing, were then calculated using CFD. A time-varying spatially uniform flow was specified as the inflow boundary condition of the computational domain. The results indicated that both the lift and drag forces of the expert jumper increase rapidly during the initial flight when the jumper's posture changes drastically. Thereafter, drag force decreased considerably, but the decrease in the lift force was less drastic. Later in the flight phase, the lift force acting on the expert jumper increased, and throughout the flight phase, the lift-drag ratio of the expert jumper remained higher than that of the unskilled jumper.
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BFBNIB, FSPLJ, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The profile of the inrun is crucial in ski jumping. With the development of technology, a considerable number of geometric lines have been proposed from a mathematical perspective and applied to the ...inrun. The third power function is the latest standard design of the transition zone profile proposed by the International Ski Federation (FIS). Therefore, the transition zone profile (third power function) was studied. The research on athlete’s force states can help make the profile better meet the competition requirements. The dynamic differential equations of the athlete were first obtained by considering air resistance and skiing friction. Mathematica was used to solve the equations, and the skiing velocity of the athlete at each structural point was obtained. Meanwhile, the skiing velocity of the athlete at the arc and the third power function were compared with the force. The results show that, under the condition that the length and height of the inrun are the same, there is no difference in the athlete’s skiing velocity. By comparing the athlete-exerted forces under two types of profiles, it was found that the third power function will make the athlete-exerted forces slowly increase without instantaneously raising the point of the arc, which is conducive to the maintenance of the athlete’s movement. It was shown that the third power function has a great advantage in controlling the reaction force of the athlete. Therefore, the inrun with a third power function in the transition zone is more conducive to the athlete’s skiing, which further improves the level of competition and optimizes the original inrun system. It can provide theoretical support for the application of the geometric profile of the ski jumping inrun at the Beijing Winter Olympic Games.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Even though the take‐off in ski jumping is decisive, athletes only have a very limited number of training trials on the actual ski jump to practice under real ski jump conditions. Hence, various ...imitation jumps aiming to mimic the hill jump are performed during daily training. These imitation jumps should therefore mimic the kinematic pattern of hill jumps appropriately. This study aimed to identify imitation jumps that resemble hill jumps regarding four performance‐related biomechanical criteria: maximal vertical take‐off velocity, maximal knee extension velocity, maximal forward‐directed angular momentum and anterior shift of the center of mass. Therefore, a three‐dimensional analysis of the take‐off during six different modalities of imitation jumps as well as hill jumps for validation was carried out in nine professional ski jumpers. Imitation jumps from a rolling platform show better agreement than stationary jumps and three out of the four parameters were best resembled via an imitation jump that included ski jumping boots. Thus, non‐hill take‐off training should be performed with complex imitation jumps to mimic the actual ski jump. Except for the vertical take‐off velocity, we could identify one imitation jump type that is not statistically different to the hill. Consequently, the individual deficiencies of the athletes can be addressed and specifically trained using the appropriate imitation jump. These information about the similarity between imitation jumps and real hill jumps are highly relevant for trainers and athletes in order to effectively design their training programs.
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BFBNIB, FSPLJ, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A number of new winter sports facilities were constructed in the city of Erzurum for 2011 FISU—Universiade Winter Games, some of which constituted the first examples in Turkey. One of those is the ...ski-jumping complex, which hosts 5 runways along with a cluster of structures in various sizes and annexes, complementing the runways. On the northern slope of Kiremitlik Hill, where the complex is situated, a landslide occurred on 15th July of 2014, leading into complete collapse of the runways and major damage to the entire facility. This study presents a technical summary and forensic analysis of the formation of this natural hazard to illuminate the causes that cumulatively led to this engineering failure that created a massive material loss. In this work, we investigate the issue from geological, geophysical and geotechnical perspectives to illuminate the true causes of this engineering failure. We also hope that this technical evaluation provides an example for engineers as well as public administrators not to overlook the critical ground conditions and well-established design principles of civil engineering.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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