Biomechanical differences in double poling (DP) for world- and national-class female elite cross-country (XC) skiers during a 10-km classical race

• Introduction The DP technique of classical XC-skiing involves both the upper and lower body (Holmberg et al.,2005) and has become more important the last years with skiers using exclusively DP during some competitions. Our purpose was to characterize biomechanical differences in DP by world- (WC) and national-class (NC) women skiers. Methods The participants were 40 elite female XC skiers (20 WC and 20 NC) who competed in the 10-km classical race at the Norwegian National Championships, 2016. On a flat measurement section (22 m long) 0.8 km from the start, the skiers employed DP only and were video-filmed (Panasonic GH4, 96 Hz). Three DP cycles were analyzed using the Kinovea software (France, v 8.25) for joint and pole angles at pole plant (PP) and pole off (PO), as well as cycle length (CL) and rate (CR), and poling (PT) and swing times (ST). Results The total racing time for the WC-group was 10.5% faster than for the NC-skiers, with no differences in CL, CR, PT or ST. The WC-group skied faster on the flat section (6.30±0.23 vs 6.04±0.25 m/s) and exhibited a smaller ankle-shoulder angle relative to horizontal at PP (73.0±1.8 vs 75.0±1.5°) and a smaller hip angle at PO (62.7±5.2 vs 69.1±6.4°) with no difference in minimal trunk angle with respect to horizontal (19.2±3.2 vs 21.7±4.8°). 27 of the skiers (15 WC and 12 NC) used active heel raise to create force. There was a difference between the groups for when the heel raise ended, with the NC-group stopping just before PP and the WC-group after. No difference between the groups were found for when the heel raise started . There was a negative correlation between DP velocity and total racing time (r = -0.48, p<0.05) and a positive correlation between total racing time and the ankle-shoulder angle relative to horizontal at PP (r = 0.54, p<0.01), the hip angle at PO (r = 0.51, p<0.01) and minimal trunk angle relative to horizontal during the cycles (r = 0.41, p<0.01). Discussion The WC-group had 4.1% higher DP velocity which correlated with total racing time. Moreover, the finding that faster skiers have a more forward lean of the body at PP and a better timing of the ending of the heel raise, indicates that they can bring more bodyweight on their poles at PP. The WC-group had a smaller hip angle at PO which is in line with the findings of Lindinger et al.(2009). This study shows the importance of a high relative velocity during DP sections of the track and highlights the benefit of a more forward body position at PP to create higher DP velocity in female XC skiers. References Holmberg, H.C., Lindinger, S., Stöggl, T., Eitzlmair, E. & Müller, E. (2005). Biomechanical analysis of double poling in elite cross-country skiers. Med Sci Sports Exerc, 37(5), 807-818 Lindinger, S., Stöggl, T., Müller, E. & Holmberg, H.C. (2009). Control of speed during the double poling technique performed by elite cross-country skiers. Med Sci Sports Exerc, 41(1), 210-220

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Idrottsvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Sport and Fitness Sciences (hsv//eng)

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)