The purposes of this study were 1) to examine the occurrence of the stretch-shortening
cycle (SSC) in the three principal techniques of ski skating and 2) to test the hypothesis
that differences in SSC behaviour may explain the choice of a technique when the grade
is altered. Ten highly skilled male crosscountry skiers roller skied at 5.3 ± 0.1
m · s-1 using the V1 skate (V1). V2-alternate (V2A), and V2 skate (V2) techniques. Knee and
ankle joint kinematics, EMC of the vastus lateralis (VL) and gastrocnemius lateralis
(CL) muscles, and roller ski velocity were recorded during the last 40 s of each bout
of roller skiing. The existence of an EMC signal during the eccentric phase prior
to the thrust, as well as the lack of significant delay between the two phases, showed
that SSC occurs in the three techniques of roller ski skating with the exception of
50 % of the subjects at the weak side knee with V1. The VL stretching velocity over
the eccentric phase was higher (p < 0.005) with V2 and V2A than V1, indicating that
less elastic energy was stored in the lower limbs extensor muscles with V1. This could
partly explain why this technique is not used on flat terrains during races. However,
no differences of average EMC activity or IEMC existed between techniques for either
GL or VL during the concentric phase, suggesting that the theoretical advantage due
to the SSC behaviour is minor in roller ski skating.
Key words
Cross-country skiing - roller ski skating - stretch-shortening cycle - joint kinematics
- EMC
