Search results for "Jumper"

Is it still important to be light in ski jumping?

2019

In ski jumping low body weight development resulted in some serious underweight problems and therefore the International Ski Federation (FIS) decided to solve the problem by relating maximum ski length to Body Mass Index (BMI) in 2004. The present study examined the current relationship between body weight, ski length and performance (jumping distance) in ski jumping. By adopting the BMI regulation to specifications for competition equipment, the FIS succeeded in stopping the alarming development of underweight problems in ski jumping. However, as the results of the present study show, the BMI regulation adopted by the FIS has reduced the advantage of being light, but despite the use of sho…

Lower strength of the human posterior patellar tendon seems unrelated to mature collagen cross-linking and fibril morphology

2009

The human patellar tendon is frequently affected by tendinopathy, but the etiology of the condition is not established, although differential loading of the anterior and posterior tendon may be associated with the condition. We hypothesized that changes in fibril morphology and collagen cross-linking would parallel differences in material strength between the anterior and posterior tendon. Tendon fascicles were obtained from elective ACL surgery patients and tested micromechanically. Transmission electron microscopy was used to assess fibril morphology, and collagen cross-linking was determined by HPLC and calorimetry. Anterior fascicles were markedly stronger (peak stress: 54.3 ± 21.2 vs.…

Aerodynamics of Ski Jumping

2016

Ski jumping is an exciting and primarily competitive sport involving both ballistic and aerodynamic factors. The ballistic factors are release velocity and release position of a ski jumper from the take-off table, whereas aerodynamic factors include the gliding properties of the jumper/ski system (velocity, suit design, surface area, posture of the jumper/ski system, resisting and lifting forces). Both ballistic and aerodynamic factors place special demands on the jumper so that he/she can, for example, optimally maximize the vertical lift and minimize the drag forces. Ski jumping has attracted spectators 200 years and it has undergone several notable steps in the development of performance…

Analisi dei fattori di prevenzione del "jumper's knee" nella pallavolo

2005

Take-off aerodynamics in ski jumping

2001

The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, res…

Biomechanical loading in the triple jump

2000

The triple jump is a demanding field event in which a jumper must tolerate extremely high impact forces while maintaining high horizontal speed. The present study was designed to clarify the mechanical loading characteristics and the role of neuromuscular function in the triple jump. Seven national triple jumpers (4 males, 3 females) volunteered to perform 3-6 jumps. The mean best performances were 14.32+/-0.45 m and 11.90+/-0.28 m for males and females, respectively. The three longest triple jumps for each jumper were selected for final analysis. The mean contact times were 0.139 s (hop), 0.157 s (step) and 0.177 s (jump). The largest ground reaction forces were observed in the step (15.2 …

Biomechanical Comparison Between Sprint Start, Sled Pulling, and Selected Squat-Type Exercises

2013

The purpose of this study was to compare kinetics, kinematics, and muscle activity among sprint start, sled pulling, and selected squat-type exercises (countermovement jumps [CMJs] and 1/2-squats with various loads) and also to examine how these exercises correlate with the performance time of the block start (10 m). Nine male athletes (4 sprinters, 3 decathlonists, 1 long jumper, and 1 triple jumper: age = 24.9 ± 3.9 years; 100-m record = 11.35 ± 0.29 seconds; track and field training years = 11.8 ± 3.1 years) volunteered as subjects. The comparisons were made with regard to the block phase (the phase of force production toward starting blocks) of the block start. In nearly all exercises, …