Nilsson Johnny, Tveit Per, Eikrehagen Olav
Norwegian University of Sport and Physical Education, Oslo, Norway.
Sports Biomech. 2004 Jan;3(1):85-107. doi: 10.1080/14763140408522832.
The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross-country skiing techniques. Eight skilled male cross-country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross-country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self-selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross-country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross-country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross-country skiing techniques.
目的是研究运动周期时间模式对速度的适应性，并确定不同古典式和自由式越野滑雪技术在最大速度水平下的速度、周期频率和周期长度的差异。八名熟练的男性越野滑雪者在平坦的越野滑雪道上滑行时，用数码摄像机在矢状面进行拍摄。滑雪者进行了三种古典式技术——对角步、蹬冰双杖和双杖技术，以及四种自由式技术——桨式舞（2档）、双舞（3档）、单舞（4档）和组合滑板（5档），速度水平为四个不同的自选速度——慢、中、快以及他们的最大速度。通过视频分析系统分析不同速度水平下不同技术的周期持续时间、周期频率、周期长度以及相对和绝对周期相位持续时间。结果发现，在所有测试的古典式和自由式技术中，从慢速到最大速度，周期频率均显著增加（p <.01）。同时，所有被研究的滑雪技术的绝对相位持续时间均显著减少。周期长度有微小的、不显著的变化，且周期频率随速度显著增加，这表明古典式和自由式越野滑雪风格在很大程度上依赖于周期频率的增加来适应速度。一个显著的发现是相对相位持续时间随速度保持恒定，这表明两种越野滑雪风格在速度适应方面的神经控制得到了简化。对于从业者来说，了解在速度适应中增加周期频率而非周期长度的重要性，可用于优化速度的快速提升。关于绝对相位持续时间减少的知识，尤其是推进相位持续时间的减少，表明需要进行力量和技术训练，以便在高周期频率和滑雪速度下产生力量。相对相位持续时间随速度保持恒定这一知识，可用于简化不同越野滑雪技术的学习。
