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DOI: 10.14526/2070-4798-2021-16-2-9-15
Kinematic indices analysis of elite racing skiers' technique in an individual
classical style sprint
Sergey A. Bratchikov, Valentina G. Senatskaya*, Sergey S. Dubrovinskiy
Russian State University of Physical Culture, Sport, Youth and Tourism (State Central Lenin Order
Institute of Physical Culture), Moscow, Russia ORCID: 0000-0003-0616-018X, serjogazbs99@mail.ru ORCID: 0000-0001-8663-1548 senatskaya.valen@mail.ru* ORCID: 0000-0002-8304-373X oxbow2004@mail.ru
Abstract: Nowadays there is an active increase of sports-technical results in skiing race. It concerns not only skating stride but also classical techniques. High level of sports results demands constant and hard work over the technique improvement [3, 5]. As multi-tour sprint disciplines were included into the Olympic program there are considerable changes in the technique of the most qualified racing skiers. Analysis of the structure of present elite skiers' movements proves great effectiveness and efficiency of the frequency of sliding steps increase in terms of their length preservation or insignificant decrease [6]. Some research works stated that the length and frequency of the cycle (step) in cyclic kinds of sport are informative indices. They characterize the levels of technical and speed-power oriented readiness of athletes. Materials. The article presents the results of the main kinematic parameters analysis of classical skating steps technique among the winner and the prizewinners at World Championship 2021 in Oberstdorf in an individual skiing sprint. These parameters determine the effectiveness of competitive activity. Research methods. Information sources analysis and summarizing, official competitions protocols analysis of World Championship 2021, empiric (sports results and indices gathering, handling, analysis and systematization) and mathematical-statistical research methods, video analysis method. Results. We studied tournament distance speed and its components (frequency of the cycles), angular indices of the alternate two-step classic skiing steps technique at V4, V2 rises and the final race. We defined the main peculiarities of the skiing route relief at World Championship 2021 in an individual sprint. They mainly define the technique and tactics of competitive activity in skiing sprint. The main results of the research include the following individual model characteristics of Johannes Klaebo. He is the leader of modern skiing race: dynamics of distance speed in qualification - 8,50 m/s, in quarter final - 8,56 m/s, in semifinal - 8,54 m/s and in the final race - 8,44 m/s. It proves the application of the maximal speed preservation tactics from race to race. Maximal values of a competitions winner movements frequency were achieved in a final race: at the first rise - 82,4 c/min, at the second rise - 76,4 and at the third rise - 97,2 cycles/min. We defined angular characteristics in the III phase of alternate two-step classic skating steps technique at the final rise: degree of the stationary foot flexion in a knee-joint is 118°, degree of a take-off leg flexion in a knee-joint is 69°, angle of body inclination is 146°, the angle of ski separation of a take-off leg from the support is 30°. The results analysis helped to determine the range of regularities. They provide high effectiveness in sprint. The results of the held research works help to reveal the tendencies of modern technique of skiing development using classical style. Conclusion. Received during the research results prove, that the variability of the elite racing skiers technique is determined by the ability to provide operative correction of movements in terms of external conditions and a functional state of an organism change. It is also the final stage of athletes' technical mastery. The results can be used for technical mastery improvement in racing skiers, the training process individualization and help to predict sports results in the main competitions. Keywords: elite racing skiers, competitive activity, skiing sprint, routes relief, technique, tactics.
For citation: Sergey A. Bratchikov, Valentina G. Senatskaya*, Sergey S. Dubrovinskiy. Kinematic indices analysis of elite racing skiers' technique in an individual classical style sprint. Russian Journal of Physical Education and Sport. 2021; 16(2): 11-16. DOI: 10.14526/2070-4798-2021-16-2-9-15
URGENCY
An individual sprint is a competitive discipline in skiing race, included into the program of World Championship since 2001 and into Winter Olympic Games since 2002, held at relatively short distance with individual and group start depending on the stage of competitions [3].
Nowadays there is an active increase of sports-technical results in skiing race. It concerns not only skiing stride but also classical techniques. High level of sports results demands constant and hard work over the technique improvement [3, 5]. As multi-tour sprint disciplines were included into the Olympic program there are considerable changes in the technique of the most qualified racing skiers. Analysis of the present elite skiers' movements structure proves great effectiveness and efficiency of the sliding steps increase frequency in terms of their length preservation or insignificant decrease [6]. Some research works stated that the length and frequency of the cycle (step) in cyclic kinds of sport are informative indices. They characterize the levels of technical and speed-power oriented readiness of athletes [3, 5]. Technical improvement in cyclic kinds of sport, including skiing race, connected with endurance demonstration, demands high effectiveness of recurrent movements and their efficiency [1, 2, 4]. In the research works of Niels 0rtenblad (2018) it was stated that quick repulsions fulfillment demands more developed participation of muscle fibers of the II type (quick muscle fibers). These research works show that the increase of the time of making an effort can provide energy saving and prevent tiredness in quick muscle fibers owing
The main objectives of the research are connected with the main kinematic indices revelation of elite racing skiers' technique in an individual classical style sprint at World Championship 2021. They are also connected with studying the structural characteristics of a skiing rout relief. It gives an opportunity to study the peculiarities of competitive distances for skiing sprint organization and the priority ways of movement in this competitive discipline.
MATERIALS AND METHODS
Practical material of the research was received on the basis of official competitions protocols analysis from World Championship 2021 (an official site https://www.fis-ski.com/). During the research we defined the dynamics of tournament distance speed in qualification, V4, V2 and the final race of an individual sprint. In order to calculate the main kinematic indices of classical skating steps technique of a winner and prizewinners of an individual sprint we used "Kinovea" computer program. This program helped to define angular characteristics of the alternate two-step classic skating steps at the key parts of the route. In order to realize the set objectives we used empiric (sports results and indices gathering, handling, analysis and systematization) and mathematical-statistical research methods, video analysis method.
RESULTS AND DISCUSSION
The results of studying tournament distance speed of a winner and prizewinners in classical style skiing sprint at World Championship 2021 helped to reveal the tendencies of the average speed change at different stages of sprint (table 1).
to a partial inclusion of the 1st type fibers [7,8,9,10].
Table 1 - Tournament distance speed analysis of a winner and the prizewinners of an individual sprint at World Championship 2021 with classical style
Athletes Stages of competitions, the average speed, m/s
Qualification V4 of final V2 of final final
J. Klaebo 8,50 8,56 8,54 8,44
E. Valnes 8,34 8,55 8,53 8,41
H. Taugboel 8,20 8,45 8,29 8,41
Mean value 8,35±0,15 8,52±0,06 8,45±0,14 8,42±0,02
In accordance with the presented results, the highest speed of competitive distance overcoming was achieved in quarter final race (8,52±o,o6 m/s). We revealed gradual intensity decrease of competitive activity from the race to race. It was defined by the average speed of movement change for 0,07 m/s (0,8 %) in semifinal race and for 0,1 m/s (1,2 %) in the final race. The average speed decrease in semifinal and final races was in terms of all organism systems tension with the increasing tiredness and a distinct air temperature increase (in qualification - +10C, in the final - +17C. The temperature indices during the whole period of sprint competitions (2001-2021) have maximal values.
As a result of the held competitions protocols
analysis we revealed the main technical parameters of skiing routs relief. Rout relief mainly conditions the technique and tactics of competitive activity in skiing sprint. At World Championship-2021 an individual skiing sprint was held at 1,5 km route. It should be noted that according to its structure the circle included three rises of B category, four parts of flat-hilly ground and three slopes. Route relief, its components, structural characteristics, their combinations and location on the route always differently form motor structure of racing skiers' technique.
Table 2 presents the dynamics of indices, which characterize the difficulty of skiing sprint competitive distance at World Championship-2021.
Table 2 - Technical parameters of a skiing route relief of an individual sprint at World Championship-2021 (Oberstdorf, Germany)
Route
Hist,
Amount o
para
meters
Heg
ance aura
f circles (
uration
Sum o
Route difficu
circle; htsdr
imai
ength, mT
rop, m
Maximal rise, . m
eg
hts dr
ty, mQPm
Route harmony
Relief characteristics'
1 (1531)
_21_
_LS_
-51-
33,3
0,85
In an individual sprint at World Championship-2021 the indices of the rises, slopes and flat-hilly grounds total duration have the following percentage ratio: B category rises - 18%, slopes length- 21%, flat-hilly grounds - 61% of the total route length. It proves demands increase to the level of power oriented qualities and power oriented endurance of athletes. The main ways of movement on a skiing route in an individual sprint in a final race at World Championship-2021 in Oberstdorf were the following: alternate two-step classic skiing - 37%, simultaneous double poling - 43% and other ways of skiing, which athletes used during the turns at flat grounds of the route (approximately 20%).
As a result of an alternate two-step classic skiing movements analysis frequency at the rises of the winner Johannes Klaebo at different stages of sprint it was stated that the highest frequency was achieved by him in the final race: at the 1st rise -82,4, at the 2nd rise - 76,4, at the third rise - 97,2
cycles per minute. These model indices prove that J. Klaebo effectively uses the technique of sprint potential saving from race to race, demonstrating maximal frequency of movements in the final (picture 1).
Different situation is in bronze prize winner of an individual sprint H. Taugboel. Maximal indices of movements frequency at rises he shows in quarterfinals. During the competitions there was the tendency to frequency of movements decrease of an alternate two-step classic skating steps at rises from race to race (102,6 c/min, 97,8 and 94,8 c/min).
Thus, H. Taugboel's indices of movements frequency decrease from quarterfinal to final race were 8,2%.
During the research we analyzed video of the technique of alternate two-step classic skiing steps of the winner J. Klaebo in an individual sprint at rises in a final race. In order to define angular indices of the technique we considered the III rd
phase, "sliding with a squat on a stationary foot", off the ski of the lift-off leg from the support (table where there are the greatest differences in the angles 3). during lift-off leg flexion in a knee joint and taking
Fig. 1. Dynamics of changing of a winner and prize winners movements frequency in an individual sprint at key parts of the distance at World Championship-2021
Table 3 - Angular characteristics of alternate two-step classic skating steps at rises of the winner J. Klaebo in an individual sprint at World Championship-2021
Indices The angle of stationary foot flexion in a knee joint, degree The angle of lift-off leg flexion in a knee joint, degree Body slope angle, degree Angle of ski take off of the lift-off leg from the support, degree
1 rise 126 109 136 13
2 rise 128 105 132 13
3 rise 118 69 146 30
Mean value 124 94,3 138 19
Standard deviation 5,29 22,03 7,21 9,54
□ The angle of lift-off leg flexion in a knee joint
□ angle of ski take off of the lift-off leg from the support -frequency of movements
Cross valiant
Fig. 2. Kinematic characteristics of alternate two-step classic skiing steps technique of the winner J. Klaebo ^t^ses^n^hefinal^ace^f^n^ndmdual^prirt
The winner of the competitions at the first two rises demonstrated traditional technique of alternate two-step classic skiing steps. The typical features of this technique are kinematic characteristics of the body, first of all in "a throw" position (phase III). It is demonstrated by the angles of flexion of the lift-off leg in a knee joint (109° and 105°), and the angle of ski take off from the support
- 13°.
J. Klaebo's alternate two-step classic skating steps technique at the third rise differs significantly from a traditional technique, as its structure is close to "cross variant" running - not deep squat on a stationary foot with shin lash of the lift-off leg, the absence of skate and the decreased amplitude of movements. The degree of the lift-off leg flexion in a knee joint was 69°, which was 36.7% sharper than at the first rise. Speaking about the angle of a ski take off of the lift-off leg the angle increases significantly from 13° to 30°.
Such way of movement helps to decrease muscle efforts and is more effective in sprint disciplines of skiing races, where special endurance is the main limiting factor.
CONCLUSION
Received during the research results prove, that the variability of the lite racing skiers technique is determined by the ability to provide operative correction of movements in terms of external conditions and a functional state of an organism change. It is also the final stage of athletes' technical mastery.
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Submitted: 23.04.2021 Author's information:
Sergey A. Bratchikov - Student, Russian State University of Physical Culture, Sport, Youth and Tourism (State Central Order of Lenin Institute of Physical Culture), 105122, Russia, Moscow, Sirenevyi Blvd, House 4, e-mail: serjogazbsQQ@mail.ru
Valentina G. Senatskaya - Senior Lecturer, Russian State University of Physical Culture, Sport, Youth and Tourism (State Central Order of Lenin Institute of Physical Culture), 105122, Russia, Moscow, Sirenevyi Blvd, House 4, e-mail: senatskaya.valen@mail.ru
Sergey S. Dubrovinskiy - Senior Lecturer, Russian State University of Physical Culture, Sport, Youth and Tourism (State Central Order of Lenin Institute of Physical Culture), 105122, Russia, Moscow, Sirenevyi Blvd, House 4, e-mail: oxbow2004@mail.ru
