Thursday, May 20, 2010

Biomechanics and lower leg dynamics.

To help understand this post, please refer to the Photos in the last three posts:

There is an interesting point to be made about the Austrians and their slalom skiing. Especially if you pay attention to the amount of outside leg length used to keep the pressure building by the Austrian skier compared to the US skier. Almost all flexing and tipping is done with the inside leg by the Austrian. He used almost all inside ankle and leg movements to change what he wanted on the outside leg. The outside leg is controlled by the ankle, which gives the knee some slight passive angulation (frame 2and 3). (Kinetic chain in action) After the critical point at the gate, the Austrian skier uses flexing of the outside leg, to control pressure and direction.

The American skier has more knee drive (to acquire angle) and has to work harder to achieve high angles to get his outside ski to hold and turn. His outside boot is almost booting out. Unfortunately, for him the method he uses includes femur rotation, which is steering. This has immediate negative consequences to his stance ski performance. He is steering his outside leg, although he wishes he didn't have to. Here is a "case and point" where leg steering demonstrates poor results that kill a skier's turn. Is he doing this on purpose? No.

He is forced into this by his boot set up or alignment. Notice how all the Austrians have a stronger boot set up? Check the third skier's alignment in the Blog. It's much riskier to be set up outside or positive as the Austrians are, but it does eliminate almost all need for leg steering. Especially unwanted outside leg steering caused by a soft alignment set up. They know this, leg steering is a killer in all skiing.

Why then do I so often acknowledge passive leg steering happens in PMTS technique. Because it does, but it's totally different leg steering. PMTS's goal is to accomplish the same type of steering, as the leg steering you see in the Austrian skier, (passive, kinetic chain, leg movement, keeping the body in balance) not active femur steering.

Just like the Austrian skier, PMTS resulting femur movement is passive. It is minimal and it is controlled with and by correct ankle tipping and flexing movements. In the PMTS system, our muscles are not trying to twist the femur, as instruction in traditional methods advocate. At the highest level of skiing racers avoid steering at all costs. This comparison shows why.

1 comment:

geoffda said...

Harald, these last five posts are instant classics. Please make sure they don't disappear. Aside from the excellent commentary on what makes great skiing great skiing, this is probably the best write up on why soft (undercanted) alignment is so crippling for skiers. Great information here. Thanks!