EXTENSION/PENDULUM EFFECTS


Recent World Cup results in Are, Sweden in the women’s slalom and men’s GS have created a perfect seque to discuss the technique that all racers on the podium have in common, the extension/pendulum effect technique. The women’s slalom was a virtual horse race photo finish. And although Shiffrin didn’t make the podium, her results sent a clear message that any rumours of her competitive demise have been greatly exaggerated. While the women’s slalom was almost a dead heat, Austrian Michael Hirscher literally blew away Ted Ligety in the GS by 1.2 seconds. With all top technical racers rapidly adopting the extension/pendulum effect technique, reaching the podium is fast becoming a case of who is doing it the best.

The reason for the sudden seismic shift in technique is that until the emergence of Ligety and Shiffrin extension had long been associated with up-unweighting. In Burke Mountain Academy’s YouTube video, Get Over It, Mikaela Shiffrin comments, “The first time I did the get over it drill I wasn’t a big fan of it……..because my coach called it up and over…. and I thought, well…., you’re not supposed to be moving up”. (http://www.youtube.com/watch?v=Bh7KF49GzOc&sns=em)

There are a two main reasons why extending on the inside leg at the end of a turn is so effective.

  1. It sets up an inverted pendulum that rotates the skier as a vertical unit about the inside edge of the inside ski out of the old turn and into the new turn. This creates rotational momentum that rotates the skier and ski past ski flat onto its new inside edge while establishing a base for dynamic inclination into the new turn.
  2. It creates a gravity like force at ski flat that enables the central load-bearing axis to transfer the load W to the foot and induce pronation. In the New York Times video, Ted Ligety describes his extension  as “creating pressure”.

But it is a serious error to assume that the racers who are currently reaching the podium with the extension/pendulum effect technique have the optimal equipment setup and/or the optimal expression of the technique. While the racers who were on the podium in Are are getting the pendulum effect component of the technique right, only a few are getting the configuration at ski flat right. When they do, it is hit and miss. Almost no racer is getting the movement sequence at what I call Ligety’s Moment of Truth, right. The most plausible reason for this is interference caused by the structures of  ski boot with the  joint actions of the foot and leg essential to the technique. The key to effective use of the extension/pendulum effect technique is the ability to rapidly transfer the load at ski flat from the central load-bearing axis to the forefoot  and especially to the ball of the great toe, something most boots intentionally prevent.

The racer in the photo below shows what the optimal form of the extension/pendulum effect technique should look like after the start of the transition phase. The relaxed, focussed look on her face indicates that she is in a flow state (DOT  13).

DeeDee

While the stance associated with technique will look familiar, most will probably not recognize the racer. The reason she is not familiar is that I took this photo more than 25 years ago, during off season training in Hintertux, Austria. The racer is former National Alpine Canada Team member, Diana DeeDee Haight. Her technique is all the more remarkable given the fact that her GS skis are 70 mm wide underfoot with minimal sidecut compared to current GS skis with their 65 mm or less width underfoot. I started working with DeeDee at Nancy Greene Raine’s request. DeeDee who was only 13 at the time was training at the Toni Sailor Summer Ski Camp in Whistler. She was the first racer I worked with. Although she had all the earmarks of a champion, I immediately recognised that her boots were limiting her potential.

In 1978 I had her change to a Lange boot. DeeDee has chunky, peasants feet that are significantly wider than the US men’s size 6 Lange shell I had sized her in. Her big toe is large and straight. The shell deflected it towards the middle of her foot. I knew this would adversely affect her balance. I am certain most would be horrified at what I did to expand the shell of her boots sufficiently for her foot to sit naturally in it with the ball of her big toe against the inner wall and with her big toe straight. I also reduced the forward lean of the cuff and adjusted the cuff cant to a more upright position so it would work with her morphology. This involved disassembling the boot, welding the rivet holes  closed and re-assembling the parts. By the time I was finished, her Langes were nothing like the boots that came out of the factory. Instead, they were more akin to a NASCAR race car that bears only a superficial resemblence to the stock factory dealer show room version. But as the saying goes, “That’s racing”.

Starting in the 1981-1982 World Cup season, DeeDee began to use an improved version of the tongue system that Podborski was using. It is similar to the one shown in the photo below except that the system was in two separate components, connected to each other with a thin leather strap. This version was closer to the one shown in the patent figure that follows with the exception of the rearward extension of the forefoot element under the inside ankle bone. This was eliminated after it was found to cause interference with pronation.

IMG_3705

US 4,534,122 1

A large gap between the forefoot and shin components ensured that the physiologic function of DeeDee’s ankle joint was not inhibited and that the load on her shin stayed centred at the upper aspect of the front of the boot cuff. When I took the photo of DeeDee in 1989, she had been using the improved version of the tongue system for 8 years. Like a Formula One driver and his or her crew chief, DeeDee was always involved in the preparation and modification of her boots. As a racer, these  were her race vehicle. She understood what I was trying to achieve and provided me with valuable feedback on whether my efforts needed fine tuning and especially when they failed to meet our objectives and expectations.  DeeDee’s technique evolved through her innate mechanism of alternating single limb support and the postural responses associated with the processes of balance and acceleration. To the best of my knowledge, no one taught her to ski this way. Instead, her technique evolved because the environment in her ski boot was conducive to the innate processes that enabled her CNS to connect with a contiguous source of GRF at the snow. Her CNS simply did what it is designed to do.

In my opinion DeeDee had the potential to become one of the greatest female technical skiers in World Cup history. Unfortunately for her, the focus of the team in her era was on speed events, especially downhill, where DeeDee was outside her comfort zone. A series of serious injuries eventually led to a decision to retire.

In my next post, I will provide my analysis  of the key events in the extension/pendulum effect technique using screen shots from the women’s slalom and men’s GS at Are, Sweden.