jbotti wrote:HH has made it abundantly clear time and time again that fore aft re balancing is done with the hamstrings which pull back the feet. There is no muscle to push your hips forward. In PMTS its all foot pull back.
J,
"There are no moving the hip forward muscles in the body. You have only the boots and the skis with which you can lever the hips into position ... You have to know or learn how to organize it once it gets projected. This is a very high end movement." - Harald Harb
Yes, the hips by themselves can't move forward, of course. But the adjacent soft tissue in the core can aid in fore/aft alignment of the CoM. The pelvic tilt, for instance, will affect shin and lumbosacral angle. This, in turn, will play a role in your stance over the ski. So, what I meant by "bringing the hips forward" - a common cue given to sprinters to fix pelvic tilt, rather than being a biomechanically correct statement --was not to "move the hips [hard tissue] forward", but rather to initiate forward movement through posteriorly tilting the pelvis by contracting the deep abdominal muscles and/or glutes.
This was just to clarify in case any confusion arose with my locution; below I explain how I came to such a conclusion.
Max,
Max_501 wrote:gaku wrote:...but I got the impression you also actively adjust your pelvis position, particularly during the high-C, maybe for additional/further precision?
What did you read that gave you this idea?
The following quotes specifically [all taken from HH's first post]:
1. "You have to know or learn how to organize it once it gets projected.
This is a very high end movement."
2. "I describe this in both my books as, “bring the feet back or pulling the feet back”, to hold them under the hips as the hips move forward and into a more direct route to the next turn. The hips move forward relative to the feet. "
And in particular this:
3. "... we tried to reference the heel pressure and how it related to pressure under the ski edge and where that pressure helped or created part of the turn. He realized that the beginning of the arc the hips needed to
stay open (reference in this case to
forward tilt). Open means not bent at the waist or at the pelvis.
The stronger position is with open or un-flexed pelvis. He had the
habit of leaning forward with the shoulders and upper body. This is a
substitute for keeping the boots under the hips."
That part specifically made me think of the role of the pelvis in getting proper fore/aft balance initiating, during, and transfering out of turns. Furthermore, I linked this, and the notion of it being a "high-end movement", with the second statement above regarding "bring the feet back or pulling the feet back". I didn't, by error, consider feet pullback a high-end movement, but controling the pelvis during each stage of a turn [so as to let proper skeletal alignment absorb most of the gravitational and centripetal forces with minimal muscle effort [pelvic tilt: glutes / abdominal wall and pelvic floor muscles; feet pullback: firing of hamstrings, gastrocnemius and to a lesser degree glutes ] - now that I considered a high-end skill requiring one to achieve refined motor control and awareness of limbs in relation to the CoM and a slope's profile. So initially, I thought Harald was saying this was another - if not more efficient - at least optional, supplementary or substitutional way of achieving the same end goal.
4. "When you are in the optimal position for the beginning of the turn you will feel you hips applying pressure to the front of the boots through the shins." - Harald Harb
My immediate thought process went like this: By posteriorly tilting the pelvis you achieve a) ankle dorsiflexion [<90 degrees]. Your CoM thus gets propelled ahead of your BoS. Your weight shifts from midfoot (or, if in a squat [anterior pelvic tilt], from heel) to the ball of the feet by using smaller muscle groups (contraction of hamstrings/gastrocnemius during the foot-pullback requires more effort than a pelvic tilt).
In hindsight I think that, while it does affect where your CoG is, the dorsiflexion of the ankle restricts lateral mobility (not an issue in sprinting), and the lumbar position might be too weak to control the dynamic conditions of a slope as opposed to a flat surface - so the skeletal alignment, due to variables I didn't first consider (slope profile; lateral movement), achieved by pelvic tilt may be sup-optimal to the one achieved by feet pullback? That makes some sense to me. If not, why wouldn't actively monitoring the pelvis' position be beneficial in establishing fore/aft balance?