HIRSCHER AND SHIFFRIN WIN BY CROSSING THE LINE


When a World Cup racer wins a GS by a commanding margin, it’s a sure sign they’ve crossed the line and the gravity of the situation is significant. But I’m not talking about  breaking any rules. Instead, I’m referring to Hirscher and Shiffrin mobilizing the force of gravity by jumping across the rise line above the gate and/or minimizing pressure while rotating their skis across the rise line towards the gate so the edges of their outside ski progressively engage and lock up as they extend and incline closing the kinetic chain. Knee extension, in combination with ankle extension, uses the momentum of COM in conjunction with the force of gravity to progressively engage and apply force to the outside ski.

Reilly McGlashan has an excellent YouTube analysis of Marcel Hirscher using this technique in the 2017 Alta Badia GS (1.) The technique Hirscher and now Mikaela Shiffrin are using relates directly to the second rocker/internal rotation, impulse loading mechanism I described in a series of posts. The text below is excerpted from a comment I posted on McGlashan’s YouTube video analysis of Hirscher.

Hirscher progressively engages his edges, especially on his outside ski then hooks a tight arc close to the gate to establish his line. Once he has established his line, he no longer needs his outside ski. He gets off it in milliseconds and uses the rebound energy to project forward with only enough pressure on his uphill (new outside) ski to influence his trajectory of inertia so his COM enters the rise line at a low angle of intersection. He gets rebound energy from the loading  of his outside ski and from what amounts to a plyometric release of muscle tension from the biokinetic chain of muscles extending from the balls of his outside foot to his pelvis. The energy is created by the vertical drop from above the gate to below the gate similar to jumping off a box, landing and then making a plyometric rebound. Hirscher is skiing the optimal way and it shows on the clock and leader board.

Replicating the mechanism in a static environment is not possible because there is no inertia. But a device I have designed and constructed enables the mechanism to be rehearsed with the same feeling as in skiing.

The key is loading the forebody of the outside ski with a shovel down position as the leg is rotating the ski into the turn. This sets up the second rocker impulse loading mechanism that tips the ski onto its inside edge. Extending the knee and ankle uses momentum to exert a force on the snow with the ski.

The photo below shows the training mechanism head on. The white horizontal arms represent the sidecut of the ski. The platform under the foot can be adjusted transversely to change the sensitivity. Vertical plates set beside the ball of the foot and on the outer corner and behind the heel transfer turntable rotation torque to the ski created by rotating the leg internally with the glutes. The platform will only tilt under impulse loading if the second rocker can engage. Few skiers can use this mechanism because their ski boots do not accommodate second rocker biomechanics.

The link below is to a video that shows the effect of extending the knee and ankle while moving the hips forward and over the support foot (monopedal function). The stack height and minimum profile width of are FIS 93 mm/63 mm. Rotation in itself will not cause the device to tip onto its inside edge if centre of pressure is on the anatomic centre of the foot (through the centre of the heel and ball of the second toe).

Dr. Emily Splichal’s recent webinar on the Science of Sensory Sequencing and Afferent Stimulation (2.) is relevant to motor control and cognitive development associated with high performance skiing. Pay careful attention to Dr. Splichal’s discussion of the role of mechanoceptors and the fact there are none on the inner (medial) aspect of the arches of the feet which is why footbeds or anything that impinges on the inner arch is a bad thing. I will discuss the implications of Dr. Splichal’s webinar in a future post.

In my next post, I will provide detailed information on the training device.


  1. https://youtu.be/OxqEp7LS_24
  2. https://www.youtube.com/watch?v=2qPnrQ85uec&feature=youtu.be

 

 

4 comments

    1. I plan to share to basic principles of the device once I do more tests with skiers I am working with and get some data from CARV. If the CARV data from the device corroborates with the CARV data obtained during actual ski maneuvers this should serve to validate the device for movement sequence training. My experience with device accurately replicated the feel under the ball of my outside foot in skiing. But I want to make sure that a number of skiers have a similar experience. I will also be formulating a series of movement drills to help skiers and racers appreciate how wrong movement patterns can adversely affect balance and ski control.

  1. Hi! The explanation given (or as I understand it) is in direct contradiction with newtonian physics. Please remember, that all forces on the ski are perpendicular to ski, not to the path of the skier and the mechanic of the proposed device is in direct conflict with FIS regulation of minimal width of the ski.

    1. Happy New Year. Thank you for your comments. The device shown in my last post is a dryland device intended to train skiers and racers in the correct movement sequence to invoke the mechanism that everts and rotates the outside ski into the turn as the ski is rotated across the rise line (internally) with the glutes. I will elaborate on the forces in my next series of posts. If my explanation of the force is unclear or you believe it has errors your comments are valued and appreciated.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s