Acceleration phase

Posted In: The Classics

  • Avatar
    Participant
    2belite on #21685

    I definitely agree with you guys, but sometimes it's nice to play devil's advocate.
    I honestly think Maurice is doing the same thing that Carl did when he was on top. Carl had great early acceleration and never forced for frequency or cut full range or motion to get it. He allowed every thing to build up naturally, and Maurice is doing the same. However, Carl was lacking in max strength which is of great importance the first 5 meters and he also had to contend with his longer limbs, which is not an advantage in early acceleration. These two factors but him behind early, but if there is anybody that has a great "drive phase" before Maurice it was Carl Lewis.

    Mike Young
    Keymaster
    Mike Young on #21686

    Excellent posts. I think possibly the take-home point here is that departure angle, head position, trunk position, or any other factors are secondary to the fact that one needs to accelerate to top-end speed smoothly rather than shifting too early (to use car talk) and grinding the gears. Proper race distribution is key not only for correct momentum development but also for energy efficiency.

    ELITETRACK Founder

    Avatar
    Participant
    2belite on #21687

    Great points Mike.
    Here are two quotes from Dan pfaff that may help this thread along. The first one is nothing special, just some good information for any young athlete or novice coach to know. The second quote may have some implications if you think about the change in body angles he recommends for each successive stride.

    " I do not teach stay low……body lean is a product of force placed into the ground. When one starts there is no foward movement or speed so we [can] push on the ground with great force and for a long period of time. This results in foward lean, usually a 45 degree angle from the block… each successive stride finds us pushing for shorter and shorter periods of time because we are now accelerating….thus each step should be less and less lean until we are absolutely upright. The folk with the big power ratios appear to stay down longer because they are able to apply force for a long time frame….this is due to training for power and proper biomechanics…. forced lean foward or trying to keep the hips low is a mistake and sets one up for injury."(Dan)

    "Things that we key during drive phase, 0-40m….each stride gets uniformly longer; each stride gets uniformly faster, ground contact times lessens each step; air time between contacts increases uniformly; total body angles to the ground change 8-10 degrees each successive stride."(Dan)
    Thoughts?

    Avatar
    Participant
    jjh999 on #21688

    "Things that we key during drive phase, 0-40m….each stride gets uniformly longer; each stride gets uniformly faster, ground contact times lessens each step; air time between contacts increases uniformly; total body angles to the ground change 8-10 degrees each successive stride."(Dan)

    Didn't I already say that?

    "If you are accelerating properly (each stride progressively increasing in length and speed; direction of force changing from horizontal to vertical), your torso should raise naturally as you move throught the accleration phase." (JJ)

    Must be a glitch in the matrix…

    Carl Valle
    Participant
    Carl Valle on #21689

    What is the brain thinking when your departure angles are so agressive that you are in a leaning position that feels like you can fall over? Do you need to program it to feel comfortable by reps and reps, or does the athlete learn to do this artificially?

    Avatar
    Participant
    jjh999 on #21690

    [i]Originally posted by Phoenix[/i]
    What is the brain thinking when your departure angles are so agressive that you are in a leaning position that feels like you can fall over? Do you need to program it to feel comfortable by reps and reps, or does the athlete learn to do this artificially?

    Although no one I've worked with to date has had a block clearance style as described above, I believe that movements of that degree of complexity and velocity must be properly rehearsed with reps. The athlete must learn to control and react to the power that he/she can generate. I sometimes call that "timing" when I talk to my athletes. I often see that with athletes (and experienced it myself) during the early micros (fall) when max strength levels are really popping, athletes have a tremendous ablilty to apply the force to the ground, but the motor apparatus can't quite keep up. In other words, the athlete has the ability to deliver the force, but can't optimally perform the switching motion either in flight or upon foot contact.

    In my opinion, once the requisite strength and power levels are in place for an athlete, sprinting is all about neurological suppleness-How sensitive and discrete can your neuromuscular system be? When this quality is high, you will hear athletes say stuff like, "Everything felt so fluid" or "I felt like I knew exactly when my foot was going to hit the ground" or "I was in complete control from start to finish".

    Avatar
    Participant
    2belite on #21691

    No glitch in the matrix JJ. What do you guys think about the 8-10 degree change in body angle each successive stide. Lets say we are lucky enough to coach an athlete that can depart the blocks at a 45 degree angle, with a 8-10 degree change in body angle each successive stride this athlete would be upright by 10meters. If this is so, what makes the drive phase 30 or 40meters. Is it really about body position or more about effort?

    Avatar
    Participant
    jjh999 on #21692

    Body position is a product of the application of force against the ground, not effort. Sure, an athlete can assume any particular position he/she wants, but 9 times out of 10 if you coach an athlete to "pantomime" a particular torso position, they will fail: They won't be doing the right things at track level. The '8-10 degree rise' is simply a function that should directly correlate to the change in acceleration mechanics from block clearance to maximum velocioty.

    Biomechanics and physics sure do make some of these concepts much clearer. Also exposes a lot of semantics and catch phrases. I highly recommend "The Mechanics of Athletics" by Dyson to anyone interested.

    Avatar
    Participant
    2belite on #21693

    Maybe I should have said "perceived effort." JJ, I was not trying to imply that body position in a product of effort. I am trying more to get a working definition for "drive phase"
    For example, Bruny talks about "drive phase" as accelerating as fast as you could using as little energy as possible. Maurice say you have to use as much power as possible but with as little effort as possible (in science neither of statements makes sense). With a 8-10 degree change in body angle each successive stride taking place as Dan pointed out the athlete would be up by 10meters. So what makes the his drive phase 40m? It can't be body position,because the athlete is almost upright my 10meters. Is it the perceived effort? What makes a drive phase 30-40 meters?

    Mike Young
    Keymaster
    Mike Young on #21694

    [i]Originally posted by Phoenix[/i]
    What is the brain thinking when your departure angles are so agressive that you are in a leaning position that feels like you can fall over? Do you need to program it to feel comfortable by reps and reps, or does the athlete learn to do this artificially?

    I tend to think that in most cases it's artificial. That's because if it wasn't, a person wouldn't really get into that position (instability) in the first place. A position that is unstable feels that way for a reason. The body is often times smarter than the (conscious) mind and it more than likely won't put itself into a position that it can't handle. If the power is there, the correct departure and body angle should probably feel natural. Stability can be achieved through strength and power development and to a lesser degree proprioceptive enhancement through repititions. Until those qualities are added, the instability will still be present. Especially low and unstable positions have to be artificially forced when power indicators are not present and when these power indicators are present, the same positions ceases to be an unstable position.

    ELITETRACK Founder

    Mike Young
    Keymaster
    Mike Young on #21695

    [i]Originally posted by 2belite[/i]
    "Things that we key during drive phase, 0-40m….each stride gets uniformly longer; each stride gets uniformly faster, ground contact times lessens each step; air time between contacts increases uniformly; total body angles to the ground change 8-10 degrees each successive stride."(Dan)
    Thoughts?

    These numbers don't make sense and I think I may have an explanation and possibly an answer to 2belite's question (what constitutes the "drive phase" ). First of all, we all know that runners are not fully upright at 10m. Secondly, it would be naive to think that body angles progress at a linear rate. It is more likely the case that body angles change dramatically at first, and progressively get less and less as one approaches maxV and a fully upright posture. To put this in an example, here's some arbitrary numbers for trunk angle to explain what I mean:

      [*] @ 1st step (departure angle): 45 degrees

      [*] @ 5m: 60 degrees (15 degree change from previous position)

      [*] @ 10m: 70 degrees (10 degree change)

      [*] @ 15m: 76 degrees (6 degree change)

      [*] @ 20m: 80 degrees (4 degree change)

      [*] @ 25m: 83.2 degrees (3.2 degree change)

      [*] @ 30m: 86 degrees (2.8 degree change)

      [*] @ 35m: 88.5 (2.5 degree change)

      [*] @ 40m: 90 degrees (fully upright position acheived with 1.5 degree change)

    This would reconcile the fact that trunk angle is not fully upright at 10m despite what the proposed 8-10 degree change / stride would indicate. Thoughts?

    ELITETRACK Founder

    Mike Young
    Keymaster
    Mike Young on #21696

    So then what does constitute "drive phase"……I think it's the angle of push and the ratio of vertical to horizontal impulse. This will not only determine body angle, but also acceleration curve. Having said that, we can't look at body angle and push angle independently because the body angles and push angles are interdependent on one another. Body angle determines location of COM position relative to foot strike which will in turn determine the ratio of horizontal to vertical impulse which will in turn determine the body angle of the following step, and so on…..what came first the chicken or the egg?

    ELITETRACK Founder

    Avatar
    Participant
    2belite on #21697

    Again, some great points Mike. Do you think maybe HSI is using body angles to set up push angles instead of the other way around?

    Mike Young
    Keymaster
    Mike Young on #21698

    [i]Originally posted by 2belite[/i]
    Again, some great points Mike. Do you think maybe HSI is using body angles to set up push angles instead of the other way around?

    hmmmmm……I can't say I have any idea. I'm not too familiar with John's cues.

    As an additional note to the above, the following thought came to me that ties together several of my above comments regarding the change in trunk angle and the ration of horizontal to vertical force impulse:

    ELITETRACK Founder

    Avatar
    Participant
    Kebba Tolbert on #21699

    HSI…. I don;t want to speak for John. However, it seems like they often use body positions (or at least the feel of them) to create sensations or patience. I don't know how else to explain it…

    He'll tell certain athletes to be in body position "X" [even though in reality no position is a static thing, but much more fluid] at a certain point so that they will be able to "stay on task".

    For example at 15m you should feel x

    OR

    after this sensation starts to lesson your body should feel "this way".

    I hope that helps.

Viewing 15 posts - 16 through 30 (of 80 total)

You must be logged in to reply to this topic.