Energetics and biomechanics of double poling in regional and high-level cross-country skiers
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The aim of this study was to evaluate the energetics and the biomechanics of double poling technique (DP) in two groups of cross-country skiers.
Eight high-level (HLG) and eight regional-level (RLG) skiers performed a 5-min sub-maximal DP trial, roller skiing on a treadmill at 14 km h−1 and 2°. Energetic cost (ECDP), center of mass (COM) vertical displacement range, body inclination (θ, i.e., the angle between the vertical line and the line passing through COM and a fixed pivot point identified at feet level) and mechanical work associated to COM motion were analyzed. Pole and joint kinematics, poling forces and cycle timing were also considered.
HLG showed lower ECDP than RLG, smaller COM vertical displacement range and mechanical work, whereas higher θ during the early part of the poling phase (P < 0.05). In HLG, pole inclination was higher, poling forces greater and cycle duration longer (P < 0.05). Considering all skiers, a forward multiple regression revealed that the maximum value of θ (θ max) and the minimum value of COM vertical displacement resulted the COM-related parameters that better predict ECDP (AdjR 2 = 0.734; P < 0.001). Moreover, θ max positively related to poling force integrals and cycle duration (P < 0.05).
A pronounced body inclination during the early poling phase and a reduced COM vertical displacement range concur in explaining the differences in ECDP found between the groups and among the skiers. A mechanically advantageous motion of COM during DP improves poling effectiveness, reduces cycle frequency and the mechanical work sustained.
KeywordsCross-country skiing COM Energetic cost Poling force
Blood lactate concentration
Center of mass
Energetic cost of double poling
Federazione Italiana Sport Invernali (Italian Winter Sports Federation)
- iF %
Integral of poling force normalized by body weight
Integral of propulsive poling force normalized by body weight
Integral of vertical poling force normalized by body weight
Body segment mass
Multivariate analysis of variance
Maximum value within a cycle
Minimum value within a cycle
End of poling phase
Start of poling phase
Instant of peak poling force
Statistical package for the social sciences
Mechanical work associated with forward movement of COM
Mechanical work associated with vertical movement of COM
Mechanical work associated with total movement of COM
Position of center of mass in the antero-posterior dimension
Position of center of mass in the vertical dimension
Body inclination with respect to the vertical line
The authors would like to thank the athletes and their coaches for their participation and cooperation, the military groups to which the skiers belong (Fiamme Gialle and Fiammo Oro) and the Italian Federation of Winter Sports Federation (FISI). This study was supported financially by the Municipality of Rovereto, Italy.
Conflict of interest
The authors declare no conflict of interest.
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