INTRODUCTION: Distribution of workload across the legs and upper body can affect metabolic costs in skiing. Bellizzi et al. (1998) found that the cost of generating poling force is nearly 40 times the cost of generating force by the legs through the skis. In ski skating, the V1 and V2 techniques distribute workload differently through adjustments of force timing, magnitude, and direction. This study evaluated the effectiveness of propulsion deriving from skis and poles in these two skating techniques. METHOD: Eight skiers were analyzed while treadmill rollerskiing at three individualized speeds ranging from moderate (2.5 ± 0.2 m/s) to race speed (3.4 ± 0.3 m/s) using V1 and V2 techniques in separate sessions, all on a five degree slope. Markers on skis, poles, and body landmarks were tracked at 240 Hz using a Qualisys ProReflex system. Instrumented roller skis and poles were used to measure reaction forces that were telemetered to a Computer for synchronous recording along with 3-D position data. Using ski and pole positioning to Orient the resultant reaction forces in the lab coordinate System, force components were calculated. From force data, an effectiveness index (El) was determined based on the relative proportions of propulsive and total force applied to each ski and pole. RESULTS: Average poling forces were greater in V1 than V2 but were fess effectively oriented (El of about 50% vs 60%, respectively). In contrast, average skating forces, while also greater in V1 than V2, were more effectively oriented (El of 7 to 10% vs 5 to 6% for V2 ski forces). Ski angles in V1 are significantly greater than in V2 (about 19° vs 14°, p<0.05). DISCUSSION: The effectiveness differences of Figure 2 are derived mainly from differences of ski and pole positioning. Poling phases of V2 skating involve two poling strokes per cycle, which are of shorter duration than V1 poling. The two poling strokes together compensate for the reduced propulsive force from the skis in V2 but likely come at greater cost than for V1 skating, if the Bellizzi et al. (1998) analysis applies in skating. The metabolic cost differences observed by Kvamme et al. (2005) for V1 and V2 skating support this Interpretation. CONCLUSION: Ski skating forces in V1 are more effective than for V2, while poling forces are Jess effective due to angular positioning in each case.
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