Master student A.N. Belyova¹
PhD, Associate Professor A.I. Popova¹
PhD, Associate Professor A.E. Ardashev^1
1Tchaikovsky State Institute of Physical Culture, Tchaikovsky

Keywords: Nordic combined, joint angles, stride technique, cycle time, run intensity rate, run speed, technical fitness, training system, kick double pole.

Background. Training system design and management issues are commonly recognized to be pivotal for competitive progress in modern sports. As reported by the Nordic combined research team of Tchaikovsky State Institute of Physical Culture (G.A. Sergeev, A.A. Zlydnev, A.A. Yakovleva, V.V. Zebzeev, N.B. Borisova, A.I. Popova, A.E. Ardashev, A.N. Belyova et al), technical and competitive fitness and progress depends on the sport-specific motor controls and racing skills [1, 2, 4, 5]. It should be mentioned, however, that the women’s Nordic combined elite still lags behind their cross-country and biathlon peers in the stride technicalities – that may be due to the still low competitiveness of the spot discipline on the national turf plus deficiencies in the training system design and management service. This assumption was apparently verified by Yu.V. Menkhin who found the competitive progress being facilitated by objective technical fitness rating tests and analyses with a special priority to the competitive technique versatility, quality and efficiency advancement aspects [3].

Objective of the study was to make a technical fitness analysis of the national versus foreign women’s Nordic combined sport leaders.

Methods and structure of the study. The study was run at “Aist” Olympic Reserve Sports School in Nizhny Tagil city and timed to the Continental Nordic Combined Cup final events. The competitors’ kick-double-pole skate stride techniques were video-captured on a long ascend in the Individual Gundersen (5 km race) event; followed by the data processing and analyzing by a special Kinovea software to obtain the race speed and joint angles in the push-off and glide phase and second-stride free glide phase. The joint angles were tested on the support leg by default; and the resultant stride techniques biomechanics were averaged for analysis. We sampled for the study the leading women’s Nordic combined competitors (n=18, including 9 foreign and 9 Russian).

Results and discussion. The tests found that the race speed depends on the run intensity rate, stride length and stride cycle time, with a change in either of these parameters immediately telling on the race speed. The strongest competitors were found to have the longer strides, longer monopodalic glide lengths and shorter glide times than their less skilled peers. The push-off rate was found to depend on the move strength and coordination. The run intensity rate is believed being optimal when it secures the longest glide on a time- and energy-efficient basis. It should be noted that on steep ascends the intensity rate will grow with the stride length falling and the race speed maintained by the intensity rate growth [4, 6]. Given in Table 1 hereunder is the Russian versus foreign Nordic combined competitors’ kick-double-pole long-ascend stride techniques biomechanics analysis.

Table 1. Russian versus foreign Nordic combined competitors’ kick-double-pole long-ascend stride technique biomechanics analysis

Normally the higher is the intensity rate and the lower is the run speed, the shorter is the glide length; albeit the foreign group was actually tested with the cycle glide length growth – that may be interpreted as indicative of the better technical and physical fitness of the group. Despite the accumulated fatigue, the foreign group managed to increase the run speed in Round 2 whist their Russian peers failed to keep up the speed. The meaningful growth of the monopodalic glide length in the foreign group (Temp = 8) with the shorter glide time may be also indicative of the better fitness. The Russian group on these test scales showed a minor glide length growth (Temp = 15) dominated by the monopodalic one (Temp = 13) rather than trying to reduce it, and this error may be interpreted as characteristic of the inadequate group fitness.

Furthermore, joint angles provide an extra insight into the skiing biomechanics – thus on ascends the race speed is maintained by the support leg being deeper bent in the knee and hip joints whilst the run intensity and push-off strength grows. The steeper is the uphill track the sharper is the hip angle and trunk lean angle, as the trunk lean facilitates the body weight being invested more efficiently in the push-off – at sacrifice of the dynamic balance to a degree.

To limit the trunk lean in the lumbar segment, the trunk will be lowered in parallel with the ankle and hip joint flexion. An extra momentum for the propulsive move is secured by the inertial force with the support foot always kept straight under the pelvis. For a longer glide, the athlete will move the pelvis forward and aside to ease the leg and arm movements, with the shin tilt setting the leg/ push-off direction. The thigh will be kept as vertical as possible (with the shin moved forward and pelvis ahead of the support) to effectively employ the inertial force; and the hip will actively swung with the somewhat turned pelvis to help the push leg unbend completely in the knee joint and for effective glide forward [6]. In the push-off, swing and glide phase, the push leg acts to shift the trunk, the swung leg moves forward towards the support, and the athlete glides on the support leg with the relevant ski and arm swinging action. Generally, the individual joint angles are rather specific and characteristic of the skiing technique: see Table 2.

Table 2. Joint angles in the push-off, swing and glide phase, degrees

Table 3. Group joint angles in the second-stride free glide phase, degrees

Conclusion. The study found the foreign group being better technically fit than the Russian group in a few biometrics including the run speed, stride length and cycle time, as well as the movement intensity rate. The foreign group was also tested with advantage in the joint angle control to facilitate responses to the track conditions and situations with the relevant benefits for the competitive performance as a result. On the whole, the stride techniques and kinematics of the foreign Nordic combined elite was found variable in a wide range and different in most of the test rates from the Russian group. We recommend the differences being comprehensively analyzed and the national training systems improved correspondingly to challenge the leadership of the foreign elite and step up the racing techniques and tactics on a sustainable basis.

References

1. Belyova A.N., Popova I.I., Ardashev A.E. Analysis of technique of movement of Nordic combined skiers with V2 skating. Uchenye zapiski un-ta im. P.F. Lesgafta. 2019. no.3 (169). pp. 52-55.
2. Zebzeev V.V. Methods of ski racing fitness of skilled Nordic combined skiers. Uchenye zapiski un-ta im. P.F. Lesgafta. 2015. No. 4. pp. 52-55.
3. Menkhin Yu.V. To the problem of understanding and formation of motor skill. Teoriya i praktika fiz. kultury. 2007. no. 2. pp. 12-17.
4. Sergeev G.A., Zlydnev A.A., Yakovleva A.A. Methodology for developing comprehensive targeted training programs for regional teams of qualified athletes for four-year training cycle (case study of Russian Nordic combined skiers). Study guide. St. Petersburg: Lesgaft National State University of Physical Education, Sport and Health publ., 2013. 132 p.
5. Novikova N.B. Features of skiing technique at sprint distances. Teaching aid. St. Petersburg: Nestor-Istoriya publ., 2011. 32 p.
6. Pedagogical skill and methodology for development of basic physical qualities. Skiing. Textbook. Minsk: BSUPC publ., 2016. 233 p.

Corresponding author: belyova.anka@yandex.ru

Abstract

Objective of the study was to make a technical fitness analysis of the national versus foreign women’s Nordic combined sport leaders.

Methods and structure of the study. The study was run at “Aist” Olympic Reserve Sports School in Nizhny Tagil city and timed to the Continental Nordic Combined Cup final events. The competitors’ kick-double-pole skate stride techniques were video-captured on a long ascend in the Individual Gundersen (5 km race) event; followed by the data processing and analyzing by a special Kinovea software to obtain the race speed and joint angles in the push-off and glide phase and second-stride free glide phase. The joint angles were tested on the support leg by default; and the resultant stride techniques biomechanics were averaged for analysis. We sampled for the study the leading women’s Nordic combined competitors (n=18, including 9 foreign and 9 Russian).

Results and conclusions. The study found the foreign group being better technically fit than the Russian group in a few biometrics including the run speed, stride length and cycle time, as well as the movement intensity rate. The foreign group was also tested with advantage in the joint angle control to facilitate responses to the track conditions and situations with the relevant benefits for the competitive performance as a result. On the whole, the stride techniques and kinematics of the foreign Nordic combined elite was found variable in a wide range and different in most of the test rates from the Russian group. We recommend the differences being comprehensively analyzed and the national training systems improved correspondingly to challenge the leadership of the foreign elite and step up the racing techniques and tactics on a sustainable basis.