摘要：Highlights
•
The “running” diagonal technique is characterized by more rapid cycles and, consequently, by more frequent propulsion due entirely to substantial shortening of the rolling phase.
•
With the “running” technique, the relatively longer ski-stop phase, more pronounced knee flexion, and range of movement of knee extension indicate more powerful propulsive action.
•
The greater perpendicular force at the moment of ski-stop with the “running” diagonal technique may lessen the need for grip wax when skiing on snow.
•
The more pronounced knee flexion when the legs swing forward with the “running” technique may reduce the legs’ moment of inertia and, thereby, allow more rapid action.
Purpose
This study aimed to compare biomechanical aspects of a novel “running” diagonal stride (DS
RUN) with “conventional” diagonal stride (DS
CONV) skiing techniques performed at high speed.
Methods
Ten elite Italian male junior cross-country skiers skied on a treadmill at 10 km/h and at a 10° incline utilizing both variants of the diagonal stride technique. The 3-dimensional kinematics of the body, poles, and roller skis; the force exerted through the poles and foot plantar surfaces; and the angular motion of the leg joints were determined.
Results
Compared to DS
CONV, DS
RUN demonstrated shorter cycle times (1.05 ± 0.05 s
vs. 0.75 ± 0.03 s (mean ± SD),
p < 0.001) due to a shorter rolling phase (0.40 ± 0.04 s
vs. 0.09 ± 0.04 s,
p < 0.001); greater force applied perpendicularly to the roller skis when they had stopped rolling forward (413 ± 190 N
vs. 890 ± 170 N,
p < 0.001), with peak force being attained earlier; prolonged knee extension, with a greater range of motion during the roller ski-stop phase (28° ± 4°
vs. 16° ± 3°,
p = 0.00014); and more pronounced hip and knee flexion during most of the forward leg swing. The mechanical work performed against friction during rolling was significantly less with DS
RUN than with DS
CONV (0.04 ± 0.01 J/m/kg
vs. 0.10 ± 0.02 J/m/kg,
p < 0.001).
Conclusion
Our findings demonstrate that DS
RUN is characterize by more rapid propulsion, earlier leg extension, and a greater range of motion of knee joint extension than DS
CONV. Further investigations, preferably on snow, should reveal whether DS
RUN results in higher acceleration and/or higher peak speed.
Graphical abstract
Image, graphical abstract
