Double poling technique excelling models customizable to elite cross-country skiers’ model characteristics

PhD, Associate Professor S.P. Mikhaylovskiy1
M.M. Gromov1
D.B. Selyukin1
1St. Petersburg Mining University, St. Petersburg

Keywords: cross-country skiing, modeling, biomechanical characteristics, double poling technique, technology, training, training machine, motor skills.

Background. New competitive cross-country ski racing disciplines have emerged for the last few years with many of them attracting new supporters and making notable contributions to the sport equipment design projects and the ski/ ski tracks preparation/ grooming technologies. Progress of these sport disciplines implies improvements in the racing speeds, ski stride biomechanics and special physical training technologies, with the latter giving a growing priority to the speed-strength qualities. The improvements make it possible to step up the push-off strength and race speeds in the classic and skate skiing techniques. As a result, many classical cross-country skiers use no more waxes for better traction since they may limit the racing speed. Double poling stride is normally used on the whole distance since the skis never stop and the propulsion is smoother. Foreign cross-country skiing terminology differs from the Russian one [3] that defines the double poling stride as the classical stride with no wax applied. Till recently the double poling stride was not much popular: it was used mostly on the flat surfaces, descends and, occasionally, on gentle slopes, but nowadays it dominates on distances. Generally the double poling stride allows running faster than the other strides conditional of the excellent physical fitness and technical mastery of the skier. Some prior studies have analyzed benefits of the double poling stride under different conditions [1, 2] although there are still quite a few contradictory issues in the training methods and, hence, further studies are needed to find solutions and improve the double poling stride efficiency.

Objective of the study was to test benefits of a new double poling technique perfection technology to for competitive success.

Methods and structure of the study. The study was designed to find and test benefits a double poling technique perfection technology for the training system improvement and competitive success using Concept 2 SkiErg training machine equipped with a semi-automatic control system – that is customizable to the elite cross-country skiers’ model characteristics.

The first stage of the study was intended to profile the double poling stride biomechanics in competitions. At the second stage of the study we developed model characteristics of elite skiers to efficiently apply the double poling stride models on classical distances. And the third stage was designed to offer the new double poling technique perfection technology for use on the whole distance and test its benefits.

The new double poling technique perfection technology testing experiment was run at Kavgolovo Training Center in Toksovo town. Sampled for the Experimental and Reference Group were the students of Lesgaft National State University of Physical Education, Sport and Health majoring in the Skiing Sport Training Theory and Practice. The EG was trained to simulate the perfect double poling stride, with the trainings assisted by the Concept 2 SkiErg training machine with an automatic Multimedia Coach Control System to rate progress in the perfect double poling stride mastering trainings based on the dynamic/ movement energy tests. The tests generated racing power and speed rates, metered the run distances and produced the poling action dynamometric data. In addition, progress in the muscular memory and training process emotionality was encouraged by a variety of inbuilt services including games with preset time and push-off strength rates.

The training process was managed by the Multimedia Coach Control System to model the ideal movement biomechanics and match the trainee’s actual performance with the model technique. The software offers, among other things, an exemplary video record of the elite skier’s double poling stride on different terrains, with versions of the poling techniques illustrated by rhythmic sound tracks to facilitate the training process and help the trainees keep the model mimicking technique all over the distance. In addition, the training software offers a wide range of execution tasks different in race power, speed and strength, driven by the poling process dynamometry.

Results and discussion. Having analyzed the pacing and timing aspects of the modern double poling stride technique, we found the high speed of elite racers being largely due to the cycle length and shorter poling time, with the poling-free sliding phase found meaningfully longer. The dynamometric data analyses showed that they maximize the effort in the startup phase of the poling move. The effect is attained by the high hip bending amplitude and the body mass propulsion forward and up prior to the poling move to effectively contribute the body mass to the movement sequence. The maximal initial charge in the poling sequence is secured by a harmonized action of the shoulder girdle, abdominal and leg muscles, with the push-off shortening effect achieved by a modest elbow bent.

The training model testing experiment demonstrated benefits of the trainings assisted by the Concept 2 SkiErg training machine with its training tools as verified by the EG progress in the ideal double poling stride mastering process.  Practical trainings in natural competitive environments were found to consolidate and further excel the basic double poling stride execution skills – that were tested very close (meaninglessly different) from the model ones: see Table 1 hereunder.   

Table 1. Post-experimental double poling stride execution biomechanics in the EG versus RG

 

Test rates

RG

M1±m

EG

M2±m

M1- M2

P

Points

%

1

Upper limbs push-off time, s

0,35±0,02

0,29±0,01

-0,07

20

<0,05

2

Pace, cycles/ s

0,68±0,02

0,78±0,01

0,1

12,8

<0,05

3

Cycle length, m

4,7±0,19

4,6±0,12

-0,9

19,1

<0,05

5

Joint angles at pre-push-off moment, degrees

Hip

103±11,4

105±9,2

2

1,9

>0,05

6

Trunk

41±9,2

43±7,2

2

4,7

>0,05

9

Knee

144±9,5

117±6,3

-27

18,8

<0,05

10

Ankle  

72±2,5

60±1,2

-12

16,7

<0,05

11

Elbow

88±10

73,5±7

-14,5

16,5

<0,05

12

Joint angles at post-push-off moment, degrees

Hip

84±6,4

65±5,2

-19

22,6

<0,05

13

Trunk

31±7,2

30±6,1

-1

3,2

>0,05

14

Knee

142±9,7

116±7,2

-26

18,3

<0,05

15

Ankle 

66±7,6

79±5,1

13

16,5

<0,05

16

Elbow

146±11

140±12

-6

4,1

>0,05

17

Speed, m/s

6,1±0,11

6,9±0,08

0,8

11,6

<0,05

18

Residual speed, %

16,5±0,9

23±0,2

6,5

28,3

<0,05

19

Poling strength, N

181±12

246±5

65

26,4

<0,05

20

Heart rate, beats per min

0,49±0,02

0,47±0,01

-0,02

4

>0,05

21

Classic stride on 1.2km, s

243±10

203±7

-40

16,5

<0,05

Conclusion. The elite skiers’ double poling stride profiling study with the movement biomechanics test data was run to identify the key factors of influence on the speed and offer a new double poling stride perfection training technology. The double poling technique perfection technology testing experiment made it possible to adapt the training process to the cross-country skiers’ model characteristics and work out a modern computerized training program to speed up and improve the double poling technique mastering process. The model was tested highly beneficial and more effective than the traditional training method.

References

  1. Mikhaylovskiy S.P. Tekhnologiya sovershenstvovaniya dvigatelnykh deystviy lyzhnikov-sprinterov [Technology to improve motor actions of sprint skiers]. PhD diss. abstract. Khabarovsk, 2011, 24 p.
  2. Novikova N.B., Sergeev G.V. Dablpoling na distantsiyakh klassicheskogo sprinta v lyzhnykh gonkakh [Double poling at classic sprint distances in cross-country skiing]. Uchenye zapiski un-ta im. P.F. Lesgafta, 2014. no. 7 (113), pp. 138-142.
  3. Biomechanical and energetic determinants of technique selection in classical cross-country skiing. Barbara Pellegrini, Lorenzo Bortolan, Hans-Christer Holmberg, Paola Zamparo, Chiara Zoppirolli, Federico Schena Human movement science., 2013, no. 32 (6), pp. 1415-1429.

Corresponding author: Mikhaylovskiy_SP2@pers.spmi.ru

Abstract

Modern cross-country skiing techniques are increasingly dominated by the double poling technique whenever practical on the competitive tracks. Some competitive distances are run today by the classical double poling technique only and without a friction ski wax. The study was designed to develop and test benefits of a double poling technique perfection technology for competitive success using Concept 2 SkiErg training machine equipped with a semi-automatic control system customizable to the elite cross-country skiers’ model characteristics. The new double poling technique perfection technology testing experiment was run at Kavgolovo Training Center in Toksovo town. Sampled for the Experimental and Reference Group were students of Lesgaft National State University of Physical Education, Sport and Health majoring in the Skiing Sport Training Theory and Practice.

The double poling technique perfection technology testing experiment made it possible to adapt the training process to the cross-country skiers’ model characteristics and work out a modern computerized training program to speed up and improve the double poling technique masering process.