Purpose: To further the understanding of double poling (DP) through biomechanical analysis of upper and lower body movements during DP in cross-country (XC) skiing at racing speed.
Methods: Eleven elite XC skiers performed DP at 85% of their maximal DP velocity (V85%) during roller skiing at 1° inclination on a treadmill. Pole and plantar ground reaction forces, joint angles (elbow, hip, knee, and ankle), cycle characteristics, and electromyography (EMG) of upper and lower body muscles were analyzed.
Results: 1) Pole force pattern with initial impact force peak and the following active force peak (PPF) correlated to V85%, (r = 0.66, P < 0.05); 2) active flexion–extension pattern in elbow, hip, knee, and ankle joints with angle minima occurring around PPF, correlated to hip angle at pole plant (r = −0.89, P < 0.01), minimum elbow angle (r = −0.71), and relative poling time (r = −0.72, P < 0.05); 3) two different DP strategies (A and B), where strategy A (best skiers) was characterized by higher angular elbow- and hip-flexion velocities, smaller minimum elbow (P < 0.01) and hip angles (P < 0.05), and higher PPF (P < 0.05); 4) EMG activity in trunk and hip flexors, shoulder, and elbow extensors, and several lower body muscles followed a specific sequential pattern with changing activation levels; and 5) EMG activity in lower body muscles showed DP requires more than upper body work.
Conclusions: DP was found to be a complex movement involving both the upper and lower body showing different strategies concerning several biomechanical aspects. Future research should further investigate the relationship between biomechanical and physiological variables and elaborate training models to improve DP performance.
1Department of Physiology & Pharmacology, Karolinska Institute, Stockholm, SWEDEN; 2Åstrand Laboratory, Stockholm University College of Physical Education and Sports, Stockholm, SWEDEN; 3Department of Sport Science and Kinesiology, University of Salzburg, AUSTRIA; and 4Christian Doppler Laboratory “Biomechanics in Skiing,” Salzburg, AUSTRIA
Address for correspondence: H.-C. Holmberg, Department of Physiology and Pharmacology, 11486 Stockholm, Sweden; E-mail: firstname.lastname@example.org.
Submitted for publication July 2004.
Accepted for publication December 2004.
We thank Dave Bacharach at St. Cloud State University and Lee Nolan at Karolinska Institutet for their valuable comments on the manuscript, the Wintersport Centre in Östersund for providing us the facility for this study, and Glenn Björklund for excellent technical assistance. The authors would also like to express appreciation to participating athletes for their enthusiasm and cooperation during the investigation.
This study was supported by the Swedish Olympic Committee.