Question about Mid Mark

[dj]

hello

I responded recently to a email concerning the chart... i have gone back and cleaned up and added a little to my orginal email so i hope devin will read this from here and i hope this will further explain how it helps with consistancy and correct approach run technique.

-----Original Message-----
From: rocketdb@.......................
To: davidfjohnston@yahoo.com
Sent: Wed, 25 Feb 2009 12:12 pm

Subject: General Question on Velocity and stride length
Hello David,
I was looking at your pole vault run 6 stride check mark and I believe it is very useful.
I did have questions on how you were able to achieve the comparison between Velocity (mps) and stride length through out the last six strides? Is there a formula used and does the athletes height totally become unimportant if their mechanics are correct?

Look forward to hearing from you,

Devin Barry

hey Devin

the athletes height doesn't matter if the mechanics are right.. that is correct..

stride length and stride frequency equals speed or velocity. we know that part..

also many years ago i figured out that it was proportionate. For example in the long jump if i was running faster i would have to move my run "out" or i would scratch. My leg length didn’t change between jumps only the speed. The faster I ran undoubtedly the “more correct” my technique was.

i found the same to be true in the vault.. if i ran faster, and correctly, i would be "under" in the vault unless I moved back and changed my “MID” accordingly. since the vault has a handgrip that is based on the vaulters ability to apply force at the takeoff to move that grip/pole to vertical.. i determined that law of physics also had to be proportionate.

I took some basic numbers i had for the time it took, with a stop watch left foot to left foot, over the last 6 steps to jump a certain height.. I did the numbers progressively up and down the chart and they matched with the proportions for grip, speed, jump height ..etc on the chart. My original chart had the time it should take to take the 6 steps, based on feet per second and when the scientist came out with the meters per second i did the math based on the time… and converted to MPS… and my chart still stayed within the parameters of what speed was needed or observed that it generally takes to jump a curtain height.

for example..

for "Isi" to jump 5.00 meters she will have a "MID" (six step mark) of approximately 50 feet or 15.30 in meters and a grip of approximately 4.55 meters, she will need to run approximately 8.1 meters per second and her takeoff will be approximately 12’4”/3.75 meters. Subtract 3.75 from 15.30 and you get 11.55 meters for the last 6 steps. If she needs 8.1 meters per second to move a 4.55 grip to vertical she will need to cover the last 6 steps in 1.43 seconds.

Make sense??

of course the takeoff point on the chart is based from an “average” reach height but I can tell you that is minor compared to the importance of a “correct” “MID”. Just try and make sure the takeoff is “out” based on your reach height so there is a good chance for a “free” takeoff. It is better to “chop” and be “out” than it is to stretch/reach and be “under”.

The best way to run (once the acceleration has been established) is to “tap” the ground hard underneath the body…(like a rock, as someone else has said, skipping across a pond but with a physical “tap” to give it a “boost” each time it touches the water) of course in the vault, long jump and triple jump there needs to be a slight “upright”, hips pulled under posture to have the best impulse at the takeoff/transition from horizontal to vertical. This is why the vaulter needs to break inertia with a “build up” on the approach so they can “tap” or quicken over the last 4 to 6 steps and not lose speed.

dj

[rainbowgirl28]

Hey I am in Mexico until next week, so I can't do it until then!

[dj]

hey becca

do you have the info to add the cahrt on here..

thanks

dj

[dj]

hey

i think this explains why a six step "MID" is important... even though he is 10 years younger then me... he oboviously did his home work either from som eof my work or others before him....

dj

http://www-chi.nearnorth.edu.on.ca/pole ... 0Marks.pdf

[dj]

hello

i want to emphasis some points...

The researchers have reviewed the scatters and determined if there were any patterns or
consistencies. From this investigation, they were able to conclude that jumpers use visual stimuli
from about six steps out to, steer or adjust, their running rhythm to take-off at a preferred spot. If
they felt too close, they would crowd or chop their steps. If they were too far, they would begin
to reach and over-stride. If the feeling was very uncomfortable, they would abort the attempt all
together.

If they felt too close, they would crowd or chop their steps. If they were too far, they would begin
to reach and over-stride. If the feeling was very uncomfortable, they would abort the attempt all
together.

It is preferred to keep this steering mechanism at a minimum to maximize speed and
control. If the steps are crowded, full extension of the leg is reduced and the runway speed
diminishes. If the steps are lengthened, the hips will lower creating a loss in speed, again
reducing performance levels. With this in mind, to simply record the final foot placement is not a
complete reflection of the run-up. A mid-mark assists in this process greatly.

it is preferred to keep this steering mechanism at a minimum to maximize speed and
control.

The mid-mark is usually placed six strides from the athletes take-off. The trained athlete
should be able to execute a run-up from fourteen to twenty strides, step on the mid-mark and then
run with the preferred rhythm and velocity to an efficient take-off. The observant coach will be
able to watch from the side and see the desired run-up with minimal steering. It is easy to
monitor the foot placement at the mid-mark, observe the general run mechanics through the
attack phase and then observe the jump. A poor foot placement at the mid-mark will allow the
coach to easily see crowding or reaching in the final steps. Proper information can the be
conveyed to the athlete relative to a run-up problem or another problem.

dj