Izbrani biomehanski vidiki vloge in pomena odrivne moči smučarjev skakalcev

slovenian

2017

volume 65, issue 1/2

power   ski jumping   sport   strength   take-off

Univerza v Ljubljani, Fakulteta za šport

Ski jumpers' push-off power is considered to be an important motor ability. This ability is reflected in performance of the takeoff in the support phase of the push-off, when a ski jumper is in contact with the surface. In the support phase of the takeoff, a ski jumper must develop appropriate take-off speed in the overall centre of gravity of the jumper-skis system, directed perpendicularly to the surface, and at the same time ensure optimal rotation of the body during the transition to the flight phase. During the take-off in the support phase of the take-off, the energy of the necessary power is mainly generated in the knee and hip joints. More than 90% of energy and/or power is generated in the knee and hip joints. The share of energy produced in other parts of the body is minimum. Correlation between a ski jumper's push-off power and performance decreases with the size of the ski jump, while correlation with the factors of aerodynamic efficiency of the movement technique increases. In the case of large ski jumps or ski flying hills, the smaller impulse of the take-off force can be compensated for by the stronger impulse of the buoyant force. During a ski jumper's take-off, where the explosive-ballistic type of muscle contraction prevails in the circumstance of relatively small external resistance, an improved performance is connected with the concentration of the extent of work strain in the initial part of the movement amplitude, i.e. with a typical increase in the maximum strain and a reduction in the time needed to achieve it. Such tendencies require a ski jumper to have sufficiently developed explosive power. The development of special take-off power has to take into consideration the specific regime of muscle activation that characterises the ski jumping technique.

20.12.2021