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measuring speed loss from hip instability
I've been working on making my hips more stable in my V1 skate technique,
since Zachary Caldwell pointed out my problem with that. In three sessions of practicing stable hips and some time-trial measurements both with and without poles, it looks like my "wiggly" hips were costing me a speed loss of more than 4% I've practiced so that now I can choose use either wiggling hips or stable hips when I skate either no-poles or V1 (offset) poling. I'd guess that I'll see larger gains in speed as I more fully integrate stable hips with all the other parts of my skating motion, and as I develop slightly different specific muscles for it. So thanks a lot, Zach -- 4% is a pretty nice gain for just three practice sessions. Seems like a key driver of me wiggling my hips was to have a quiet _head_ position. Stable hips plus torso-swing yields head moving from side-to-side relative to the center-line of overall forward motion on the ground. This head motion is easily seen in videos of the V1 skate of Swenson and Alsgaard. But a quiet head _feels_ better to me, so I was "counter-swinging" my hips so that in combination with my torso-swing, the side-to-side motion cancelled out up at the level of my head -- and a quiet head is a pleasant way for me to experience the world. So now I'm practicing watching out for that pleasant head-quietness -- and recognizing it as a _warning_ of 4% speed loss -- a signal to get my hips stable, facing square in my line of overall forward motion. day 1: Skated no poles on flat terrain with hands on top of pelvis side "points", good position to learn sensitivity to both hip-rotation and tension in the TrA muscle. Practiced switching between wiggly hips and stable-square hips. Thought about the hip staying out there to the side, helping my leg push out to the side. Thought about opening hips, keeping my knee pointed out in line with the ski, not dropping inward. day 2: Skated with poles V1 up hill of 8-11% grade on Jenex 6400 (faster) rollerskis. Results: -- V1 skate, wiggly hips = 5:59 -- V1 skate, stable-square hips = 5:42 day 3: Skated gentle uphill with no poles on Jenex 830 (slower) rollerskis. Held a ski pole horizontally across the front of my hips/pelvis. Observed whether the ski pole rotated side-to-side or stayed square while I skated. Found that I was pretty good at controlling selection of one mode or the other. Time-trail results: -- No-poles skate, rotating hips = 3:23 -- No-poles skate, square hips = 3:14 I was using torso-swing in all cases, so this was in no way a test of Quiet Upper Body, only Quiet Hips. With early results like that, I think I'll put lots more work into this "hip stability" thing. Ken |
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