Facts, Not Fiction

 
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    Long Jump Landings
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    I wonder if any of you with technical knowledge, know why long jumpers (and perhaps triple jumpers as well), now sit down of fall down (backwards) on their landings, vs. in the past, jumpers would land on their feet and fall or spring forward?
    It seems the latter would give a better measurement. But perhaps one cannot put their feet as far forward doing this...?
    Any thoughts?
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    #2
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    I have wondered about that too. I think maybe they now use a kind of sand that the jumper can "sail" through, so that when they sit down at the end, the mark is actually further than the original landing spot of their feet.
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    #3
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    Quote Originally Posted by noone View Post
    I have wondered about that too. I think maybe they now use a kind of sand that the jumper can "sail" through, so that when they sit down at the end, the mark is actually further than the original landing spot of their feet.
    That wouldn't help because the jump is measured from the first break in the sand nearest to the take-off board made by any part of the body.
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    #4
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    The obvious goal is to achieve maximum extension that allows jumper to fall forward instead of sitting down. Shelia Hudson, one of the smaller elite jumpers, was the master of this technique, leaving nothing but a perfectly parallel pair of size 5 footprints before bounding forward out of the pit.
    Many jumpers adopt a sideways fall to presumably minimize the loss of distance from foot plant.
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    #5
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    Maybe I didn't explain properly. Let's say the jumper lands with his heels at the 26 foot mark. He then glides through the sand before sitting down and his butt lands at the 26'6" mark. So he jumped 26 feet, just as if he had not sat down at all.
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    #6
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    Measurement is from mark in sand nearest foul line made by any part of body.
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    #7
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    Quote Originally Posted by lonewolf View Post
    Measurement is from mark in sand nearest foul line made by any part of body.
    I don't think there's any confusion about that on anybody's part, only about what it is that noone's trying to explain.

    Noone's theory isn't that sitting down behind your feet would somehow magically give you a mark that's better than the initial point where you touched the ground; rather, he's saying that the intuitive result (that sitting down behind your feet will give you a mark worse than the initial point where you touched the ground) only holds if your feet are still in the same place; if your feet have moved forward enough, you can sit down and not lose distance.
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    #8
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    The only thing that matters in the LJ is the center of gravity (~middle of your hips), so the farthest you can go is wherever the closest part of your body to the CoG hits. All you can do to extend your feet high enough to be on the same trajectory line your butt is already scribing in the air. You bend/reach forward to try and push the CoG as far forward as you can. Lewis's lean-back hitch-kick was a means to use the highest take-off angle that his speed could effectively generate and to maintain balance in the air, so he could push that CoG forward for landing.
    In older, stiffer sand, there was the possibility of overextending your feet (ahead of the CoG) and then accordioning up, keeping your butt from hitting the sand where it 'should' have. You can also see jumpers sliding off to the side trying to get the CoG on the outside of the hip - not sure if that actually extends a jump.

    Caveat - the foregoing is an amalgam of 50 years experience and (more importantly) all the biomechanics workshops I've sat through. I'd love to hear what an actual biomechanist has to say.
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    #9
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    Thank you lopenuupunut, you explained my argument well.
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    #10
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    Now I am confused. How does feet sliding forward make any difference? I cannot imagine any configuration where a butt mark could be farther from foul line than the initial foot plant which would leave a mark.

    Sand may vary slightly in grain size and angularity but displacement is affected more by how wet or dry it is.
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