pelvic rotation


Comments made by S.S. Komissarov in his paper, Dynamics of carving runs in alpine skiing. The centrifugal pendulum in conjunction with a critical examination of the biomechanics of the walking cycle and subjective on-snow experiments I did last ski seaon has given me insights into the mechanism that enables fluid dynamic skiing with directional control.

A telling statement by Komissarov is that in the fast skiing typical of FIS WC racers’ rhythmic carving turns are still possible but balanced carving turns are no longer possible. Komissarov further states that during rhythmic carving turns a skier is never in balance. I would modify this statement to posit that during rhythmic carving turns a skier is only in what can be described as a state of dynamic balance wherein neurobiomechanical processes effect tight control over variances in the orientation of the transverse plane of the base of the edged outside ski as it pertains to the alignment of the vector of opposing applied and reaction forces for a few milliseconds.

These insights explain why static balance exercises done on one foot, lateral side to side jumps where a subject lands and balances on one foot and even one ski turn exercises don’t equate with the dynamic mechanism responsible for the fluid movement of dynamic skiers.

A critical examination of the walking (aka gait) cycle raised issues that as far as I know may never have been explored. These issues have potential implications for the role of steering in the alignment of the pendulum vector of COM with the transverse aspect of the outside ski as it pertains to the edge angle in carving and the stiffening of the outside foot and leg that enables powerful carving forces to applied to the outside ski that when released act can act as catapult mechanism to propel the skier into the next turn.

Pelvic rotation appears to be a key component in the dynamic processes of both walking and skiing.

In my next post I will start to explain how I believe pelvic rotation in walking relates to pelvic rotation in a ski turn and what the differences are.