Swing Phase Mechanics during Sprinting….higher level discussion

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    Guest on #42498

    Is Dennis still using 50m overspeed cords and pulling his athletes?

    Mike Young
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    Mike Young on #42499

    Is Dennis still using 50m overspeed cords and pulling his athletes?

    To the best of my knowledge he is. I haven't been at LSU for 9 months but he did them the last time I was there.

    ELITETRACK Founder

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    purebreeze on #42500

    check this article out….

    https://www.inno-sport.net/Sprinter%20Symptoms.htm

    what do you guy think?

    Mike Young
    Keymaster
    Mike Young on #42501

    check this article out….

    https://www.inno-sport.net/Sprinter Symptoms.htm

    what do you guy think?

    It's hard to tell what he is actually suggesting…is he saying that athletes shouldn't push up using the quads? If so, how does the athlete reverse the vertical acceleration of their body towards the ground? Is he saying that athletes should pull? It kind of seems like he is? If so, does he think it should be cued?

    ELITETRACK Founder

    Carl Valle
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    Carl Valle on #42502

    My question to Mike with the Weyand study on swing times.

    Here is what I found.

    The swing times of elite athletes and regular Joes are about the same but I look at the degrees traveled (at the hip joint)for an elite guy (1996 finals) were longer and the radial swing was faster. The measurements were only on Dartfish so don't shoot me! How much contribution is from elastic response of the hip flexors from hip extension and how much is cognitive concentric response from the athlete?

    Mike Young
    Keymaster
    Mike Young on #42503

    Good question. I actually spoke with Pete and Ralph Mann (the USAT sprint biomechanist for ~20 years) about this a couple weeks back. They both verified that there are negligible differences in swing time among the best and the worst runners. They both agree that this difference is not significant and isn't really the reason they are running faster. I specifically asked if the thigh of better sprinters was moving through a greater angular range of motion (and thus potentially making the angular velocity of better runners considerably better since they would move a greater distance through a shorter period of time) and both said that this is not the case. They both concurred that the ROM essentially is the same for elite and sub-elite sprinters and that range of motion of the thigh essentially just shifts more anterior in better runners (minimizing backside mechanics). Neither commented on the elastic response of the hip flexors but heres what I think…

    In light of the above points one could easily think that the greater backside mechanics of the lesser sprinters would actually create a greater elastic response in the hip flexors than the better sprinters who display less backside mechanics….the leg travels further behind the body, placing a greater stretch on the hip flexors prior to toeoff and thus creating a greater elastic response, and a faster swing leg. This is not the case though.

    In better sprinters the pelvis exhibits a more posterior tilt and the trunk tends to be more upright. This means that at any given point of hip extension the hip flexors are under more stretch than a more anterior pelvic tilt and less upright posture. So why then would the thigh not move through a greater range of motion or move faster if the hip flexors should be under a greater stretch. I think the answer is simply a matter of lever arms and gravity. To bring the thigh from a position of moderate hip flexion (~75 degrees from anatomical standing position) up to a position of great hip flexion (with the thigh parallel with the ground at 90 degrees) requires considerably more force than to bring the thigh from a position of poor hip flexion (~60 degrees) to moderate (75 degrees) even though the angular displacements (15 degrees) are the same. This is because the higher the thigh is raised the greater its effective weight due to the increased horizontal distance between any given point on the thigh and the hip joint. This is true regadless of pelvic attitude. So in a nutshell, I do think that better sprinters have a more significant elastic response of the hip flexors but the effect of this may be washed out when looking at swing times and angular velocities of the thigh because of the mechanical advantage (but not performance advantage) that moving through the shifted range of motion that lesser sprinters typically operate in (lesser knee flexion  / lower knees) has over moving through the range of motion that better sprinters typically operate in (greater hip flexion / high knees).

    I'm certain the elastic response plays a role. Whether it is greater or less than the conscious (or subconscious) effort of the athlete I do not now. I think that it would be quite difficult to run mechanically efficient with high knees, minimized backside mechanics, high hips, etc. at 11+m/s without it.

    ELITETRACK Founder

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    senri on #42504

    so where does this lead to successful sprinters with anterior pelvic tilt. Or is there none? Do they hae a unique way to run with the pelvis tilted posteriorly?

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