ZackCapets wrote:
racin_rusty wrote:
Have to disagree with you on this. AFAIK distance swimmers kick to aid in body
rotation not for maintaining horizontal position.
I think what you and bjorn are getting at is that the foot/ankle position is very critical. This is my unvalidated suspicion as a lifelong swimmer and new aero engineer, but in good swimmers who have exceptional ankle flexibility and thus have their ankles extended during the stroke such that their foot is nearly parallel with the floor of the pool at the (rotationally) horizontal torso portion of the stroke, the feet naturally deflect just enough water to give the feet/legs buoyancy. As the ankles flex toward the shins, the flow over the feet stalls and they lose their lift. Obviously, the ankle flexion/extension varies during the kick, but the "neutral position," if you will, is with the upper surface of the foot nearly parallel (+/- maybe 10 deg) to the tibia. While kicking, the lift/separation phenomenon seems less obvious, but when the ankles are banded with the feet side-by-side, it seems more apparent. The good swimmers (who not coincidentally have good ankle flexibility) will have their feet oriented at such an angle that they generate just enough lift to stay afloat when their feet are banded thusly. Poor swimmers (who, also not coincidentally, have poor ankle flexibility in extension and will thus have their ankles flexed more toward the tibia) will have less lift on the feet, causing them to sink. By "stacking" the feet or crossing the ankles, the flow that would generate the lift is almost completely interrupted, so the feet will pretty much inevitably sink to some extent regardless of ankle flexibility.
Zack - I think you're describing this whole legs/ankles/feet issue pretty well. My only addition to your description is that it just takes a minor 2-beat kick to keep those feet up if your ankles are flexing properly such that the top of your foot is close to being parallel to your shin. As you astutely point out, and as bjorn said earlier, the closer the ankles are together when you put on an ankle band, the harder it will be to get the lift from the kick, up to the crossing over of the ankles which completely negates any possibility of keeping the legs up. With a loose ankle band where the ankles are 3-4 inches apart, the effect on the lift is much less than with a tight band.
After watching tons of swimmers kicking, pulling, and swimming over the years, I have developed a theory that, in order for your kick to be strongly contribute to your propulsive power, you have to be able to kick pretty fast relative to your swimming speed. I'll give two examples, one of a regular person and one of an elite.
1) A girl who swims at my club swims at around 1:40/100m for a 1500m at moderate effort, i.e. 50 sec/50m. She can kick 400 m at 1:05/50 m at moderate effort, or about 30% slower than she swims. She never, ever swims with the pull buoy because she says it messes up her stroke, prob because her kick is so fully integrated into her stroke.
2) On youtube, there's a video of Charlie Houchin (swam on the 2012 Oly 800 free relay) kicking 400 LCM in 4:55. Houchin swam 3:48.3 for the 400m at the Oly Trials, finishing 4th and missing the team in that event by 0.50 sec. Comparing his kick to his swim, he kicks about 29% slower than he swims.
Now obviously 2 examples do not a theory prove but my guess is that a swimmer needs to be able to kick within 30-35% (or lower) of his/her swim time before the kick is going to make a decisive diff in his/her times over a race of much distance, e.g. 400m and up. Certainly in the 50 and 100 free, 99.9% of swimmers will be kicking pretty hard, and the 200 is in the breaking point range.
In any case, that's my kicking theory thrown out for comments:)
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