Force Production in Each Leg During The Block Phase of The Sprint Start

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    Craig Pickering on #17630

    At university in the UK, students have to do a final year project as part of their course. The title of this blog post was the title of my study, and so I thought I would share what I found with the members of this site.Background- I predicted that peak rear foot force production was very important during the block phase – or at least more important than considered by the mainstream. During my

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    Carl Valle
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    Carl Valle on #108916

    would love a copy of the materials used and the data charts! GREAT POST.

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    Bjorn on #108917

    What do you think about the angle of the rear fot? Should think that a large angle will create the greatest force.

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    oshikake@ymail.com on #108929

    Wouldn’t bodymass also be a significant factor with regards to horizontal start velocity (0-10m)?.

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    JeremyRichmond on #108931

    Fortier et al. 2005 found rear force production to be around 50% greater for elite sprinters compared to sub-elite whilst front force production was almost the same between groups.

    Did you get a relationship between rear force production and block velocity?
    What about rear impulse and block velocity?

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    burkhalter on #108946

    Does anyone think the reason the better sprinters place more force on the rear block than lesser ones is because the better sprinters have better elastic qualities. I was thinking this may be some of why, especially since most people do not coach the rear foot at all.

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    JeremyRichmond on #108955

    Does anyone think the reason the better sprinters place more force on the rear block than lesser ones is because the better sprinters have better elastic qualities. I was thinking this may be some of why, especially since most people do not coach the rear foot at all.

    Unlikely to be elastic qualities otherwise we should have seen even greater front foot force production as the force production time is greater for the front foot thereby allowing for greater stretch phase.

    Not likely to be arm technique just after the gun(arms forward will increase force production but nowhere near enough to be 50%). Its not fibre type composition as time to peak force production was the same between groups. Would be interested in seeing the data from the UK study to draw a conclusion.

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    Craig Pickering on #108968

    Hi Guys

    Jeremy – I found a significant relationship between total horizontal impulse (i.e. front and back) and block POWER (I used block power as the outcome variable, as opposed to block velocity), with an r value of 0.87, and and r squared value of .76 (i.e. horizontal impulse accounted for 76% of horizontal block power). This allowed me to conclude that horizontal impulse was a strong predictor of block power. I could then determine the correlations between rear foot and front foot peak force values and horizontal block power. The correlations here were 0.55 for front foot (insignificant) and 0.77 (significant to p<0.001). I hope that answers your question, but I am happy to answer more!

    Brooke – I speculated in my discussion as to the reasons elite sprinters utilised to back block more. My possible ideas were:

    * They had stronger hip extensor muscles, and so could produce more force
    * They had received better coaching, and so their block positioning allowed greater use of the back block (studies have looked at the distance between the bloc pads and the effect on start velocity – better athletes may have had better block spaces)
    * Better athletes have better neuromuscular control and/or type IIb fibre type percentage, and so can produce force much quicker than poorer athletes (this would be important as the back foot leaves to block pad relatively quickly, whereas the front food is in contact for a lot longer!)

    If anyone else has any questions I will try to answer them, but I did this study two years ago, so it isnt completely in the front of my mind!

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