PURPOSE
The present study characterized pole and ski forces in classical technique cross-country skiing. Eight elite junior cross-country skiers performed diagonal skiing at 65%, 75%, 90%, and 100% of maximum speed on a stable 100-m-low uphill (2.5 degrees ).
METHOD
: The ski and the pole forces (vertical (Fz) and horizontal (Fy) directions) on the right and left sides were recorded separately when the skier skied over a special custom-made force platform system placed at the end of the uphill course. The entire system consisted of four separate 20-m-long rows of 1-m-long force plates connected in series, row by row.
RESULTS
When the forces were averaged for the various functional phases of skiing cycle, the ski Fz during the gliding phase decreased and the braking ski Fy and Fz remained the same with higher skiing speed. During the subsequent kick phase, both ski Fy and Fz increased significantly as a function of the skiing speed. Consequently, the Fy ratio between the ski and the pole plant increased with faster skiing speed. Simultaneously measured EMGs from five different muscles showed that the abdominals had a pattern of increasing activation with increase in speed of skiing. All the other muscles, vastus lateralis (VL), rectus femoris (RF), erector spinae (ES), and medial gastrocnemius (MG), were obviously active in the preloading and the kick phases.
CONCLUSIONS
The speed dependence of the ski and the pole force distributions in the present study are important for further understanding of the complexity of cross-country skiing. Especially relevant is to use these results as basis for studies aimed at better understanding of the propulsive force production, when more comprehensive EMG analysis is complemented with simultaneous kinematic recordings at varied slope, speed, and waxing conditions.
[1]
G A Smith,et al.
Biomechanics of Crosscountry Skiing
,
1990,
Sports medicine.
[2]
Gerald A. Smith.
Biomechanics of Cross Country Skiing
,
2008
.
[3]
P. Komi,et al.
Preloading of the thrust phase in cross-country skiing.
,
1987,
International journal of sports medicine.
[4]
Stephan Babiel.
Studies on intra-individual variability of selected cross-country skiing techniques
,
2003
.
[5]
Paavo V. Komi,et al.
Force Measurements during Cross-Country Skiing
,
1987
.
[6]
H Ekström.
The Force Interplay Between the Foot, Binding, and Ski in Cross-Country Skiing
,
1987
.
[7]
Graham E. Caldwell,et al.
Differences in Body Segment Energy Utilization between World-Class and Recreational Cross-Country Skiers
,
1985
.
[8]
P. Clifford,et al.
Poling forces during roller skiing: effects of technique and speed.
,
1998,
Medicine and science in sports and exercise.
[9]
Janet S. Dufek,et al.
Force Measurement in Cross-Country Skiing
,
1987
.