Mid Mark Chart

[ladyvolspvcoach]

It's closer to the box if the vaulter is taller, so wouldn't that mean that the midmark would need to be adjusted slightly inward, even if it is only a few inches?

you are correct! a 5' person will have a mid and take off exactly 1 foot out from a 6 ' person.....looks like that cranialanalitis has spread and developed a Russian variant..

[KirkB]

... a 5' person will have a mid and take off exactly 1 foot out from a 6 ' person ...

Ladyvolspvcoach, I have no intentions to join this debate, other than to ask for clarification of your math ...

I'm 6-0, and after measuring my reach just now, I estimate that I would reach 7-5 on my tippy-toes - whilst gripping a pole. Assuming the same proportions, I calculate that a 5-0 person would reach 6-2.

Now, assuming a 30° angle of the pole in the box (so that I can readily use the 1 - 2 - root 3 trig formula without having to crack open any text books, and without knowing their grips), I calculate that a 5-0 person would have a takeoff 2'-5" ±2" in (towards the box) from a 6-0 person.

No?

Kirk

[decanuck]

That's why the chart works--because the differences in stride length are accounted for by the differences in takeoff spot. Really people, it's just silly to think that two vaulters of vastly different heights should have the same step length. Similar maybe, but not the same. Just think Scott Huffman vs. Jeremy Scott. Or a midget and the world's tallest man. Their step lengths won't even be remotely similar, but their 6-step check marks might be. Why?

Tall people take of closer to the box, and short people take off further away from the box. True?

On an approach of sufficient length, tall people start further back than short people. True?

Now put them together. Tall people start further back and finish closer than short people. Therefore at some point in the approach, the tall and the short person will be relatively at the same spot. This, by coincidence, apparently happens to be at around the 6-step check mark!

This is how the chart endemically accounts for some of the step length variance related to height. Is it possible that a given individuals body proportions (such as long legs but a relatively short reach) place their 6-step mark further out than the chart? Yes! And vice versa.


Finally, it is not unreasonable to hold doubt about this tool until it can withstand rational scrutiny. "Just try it, it works" is not an acceptable explanation, no matter what repeated experimentation has shown. And one does not have "cranialanalitis" (read: has their head up their a**) for not blindly accepting it on faith. I wonder how many coaches here would have adopted any elements of the Petrov/Bubka model of pole vaulting if they had simply been told "Just do it, it works" without any further explanation as to how or why it should or does!

[master]

decanuck, that is not what dj says. He has said that if your reach is shorter than what he used as a his nominal vaulter (8 foot reach), than your takeoff will need to be adjusted from what the chart says and your mid adjusted the same amount and direction.

- master

[PVstudent]

Hey

ladyvolspvcoach

At least my cranioanalitis isn't so bad that I have forgotten or missed your reply to my post re the use of Dartfish.

So were the facts of the matter wrong? Can you respond or has your own dose of cranioanalitis left you with convenient amnesia!

Rather than trade insults I would be very much happier to rationally discuss the issues. The claim has been made that the mid mark chart is based on science. Do you agree? If you do then the next question is what sort of science? The sciences I hope that we are all dealing with is Newtonian Mechaninics (Classical Mechanics) and appropriate and correct use of mathematics.

DJ has produced a very useful and practical chart that does offer very valuable guidance. This is not what I am disputing. I am attempting to
find the scientific facts and principles that may rationally (acording to Newtonian Mechanics) explain the relationships that DJ's chart and claims reflect. Science based on the scientific method starts with Observation and description of phenomena and the positing of hypotheses or theories to explain the relationships revealed by the observations. The theories are rigorously tested. Some theories prove to be very robust ie., they are difficult to falsify because no evidence can be brought to bear to create doubt as to the veracity of the hypothesis. Some theories are very weak. ie there is substantial and reproducable evidence to suggest that the hypothesis being examined is of doubtful veracity. DJ has produced some observations and by means of his chart shown some relationships exist between the variables observed.

My approach has not been to attack or vilify anyone. I have continually on this thread put up my data and arguments. They are there for all to see and reflect on.

Whilst I like the word cranioanalitis it is probably a better complaint to suffer from than narrow mindedness! Please lets discuss the matter openly and plainly without recourse to insults.

After all, mistaken as I may be, I always thought that The American War of Independence and the Bill of Rights were in part to break away from rulers who ruled by "divine right" and to preserve the individual's right to "free speech" uncensored by the authority!

I am not prepared to give away the western tradition of scientific enquiry or free speech just because you wish to insult me or howl me down.

I hope readers perceive that I have asked impertinent "questions" in order to get "pertinent answers"! Blind faith is not enough nor is it an adequate response.

[master]

OK, master, I see what you did now. You put in an empty Img box.

That's a good idea - I never thought of that.

And initially, my table was wrapped, so I did Edit, just as I described (the final touch-up). That's probably when you saw it.

So now, the Grip, Ht, and Mass might fit on the same line afterall!

You might want to try that. I'm hitting the sack.

If you use both the empty Img and the Code tricks (all in the same reply), then Bob's your uncle!

Kirk

Hi Kirk,
I already did reformat the charts, using a mono-spaced font, and used an image to force the necessary width; I just did it in the original post. (see http://polevaultpower.com/forum/viewtopic.php?p=110777#110777)

Now I need help understanding your last sentence, "... then Bob's your uncle!"

- master

[KirkB]

Hey, master, you're way ahead of me!

I hope PVStudent likes the way you did that. I didn't actually realize that you could edit his posts. I hope you don't mind me trying to help him. Now that I see that he has a true PC whiz, I'll stay out of the way!

I'm still waiting to hear his explanation of the data. I was quite surprised that even Bubka wasn't very consistent in the last 4 strides.

Robert's your father's brother!

http://www.worldwidewords.org/qa/qa-bob1.htm

Kirk

[PVstudent]

A very huge plaudit to Master and Kirkb for cleaning up the tables re step rate and length 1987 Rome and 1988 Seoul Olympics that I posted.

Readers can now multiply step length and rate and see how the average speed varies from step to step and they will also be clear that average speed is derived from step length and rate in proportion. It is both step length and step rate that gives average speed. Step length and step rate are not independent of each other!

It is also possible to see from the tablulated data that individuals can have identical average speed per step and use different step length and rate ratios.

Kirkb I will answer your concerns next post. I have gone back to the original reports and will glean from them as much of the requested information you require.

At this time (I have to fully re read the original reports) the filming was done using LOCAM high speed cameras operating at 150 frames per second.

The studies used 3D motion analysis. The data were for the highest jump recorded for each jumper in the competition for which the data could be collected. Bubka's 1987 jump was for his 5.70m clearanace. They had a technical problem on his winning jump and could not use the data. The 1987 report was much more comprehensive than the Seoul one. The studies were carried out by biomechanists endorsed by the IAAF and the IOC. They used reliable and validated methods to gather the data.

I should point out that the data in the tables, report the step length and step rate data based on the determination and tracking of the path of the vaulter's centre of mass (Used Dempster's Data to locate individual body segment c of m's to derive the whole body centre of mass.) As such these values can be different slightly from those that merely track foot ground relationship. So far as I am qualified to judge the procedures used were valid and can be considered objective (reliable in that two or more analysts manipulating the data obtained identical or close to identical results.)

Yes, there is some error introduced by the "subjective" location of body segment joint centres.The digitizing was carried out by "trained" personnel. The same applies to data gathering using the same methods for sprinters and hence sprinting studies have the same small uncertainty re the accuracy of segmental joint locations and the degree of confidence we can have as to the "absolute accuracy" of the data in the individual and group case.

Once again gentlemen, Master and Kirkb, thank you for you assistance and interest in the post.

[volteur]

Step Length (metres) at the

Rome IAAF World Championships in 1987 and
Seoul Olympic Games in 1988.


Name. 4th. 3rd. 2nd. Last.
Year. Step Step Step Step

Bubka
1987 2.25 2.09 2.16 1.94
1988 2.26 2.07 2.11 1.95

Vigneron
1987 N/A 2.12 2.19 2.00
1988 2.10 2.01 2.00 2.05

Gataulin
1987 2.04 2.16 1.87 2.03
1988 2.02 2.03 1.80 1.94

Bell
1987 2.10 2.06 2.13 2.03
1988 2.27 2.05 2.27 2.10

Collett
1987 N/A N/A N/A N/A
1988 1.92 1.96 2.01 1.93

guys what this is saying to me is that the last 4 strides follow a gallop rhythm and not a steady rhythm. The gallop is the take-off rhythm* but it surprised me to see the 3rd and 4th last strides are also following this rhythm.

Is this because of holding the pole or is it a gallop found normally in straight running? Or does the pole exacerbate any natural gallup we may have? On a side note Percy Cerutty experimented with galloping on Herb Elliot.

cheers

*in that the penultimate step is longer than normal and the ultimate step is shorter than normal, found in all projection events like the jumps, throws and hurdles.

[ladyvolspvcoach]

Now, assuming a 30° angle of the pole in the box (so that I can readily use the 1 - 2 - root 3 trig formula without having to crack open any text books, and without knowing their grips), I calculate that a 5-0 person would have a takeoff 2'-5" ±2" in (towards the box) from a 6-0 person

Kirkb, At the point that I started to investigate the data in the chart, Iwas very skeptical. The first thing I did attempt ito do was to make no assumptions. If your assumtion of a 30 angle is incorrect so will the rest of our conclusios. What I did was to grab a series of poles at different lenghts . I marked 10-6 inches on each pole the went up according to the progression indicated on the chart. I had my athletes (one 6' tall and one 5') I then marked each of their take off steps standing still with their hands in a take off position (up and extended). Then I went back to the chart and compared my findings.

In each case of the 6 foot faulter the take-matched the chart within 1'2 inches either way. The data for the 5 foot vaulter had exactly the same results with a 1-2 inch variance.

I know this isn't a number crunch, but I wanted an imperical conclusion that the chart could be relied upon and would allow be to make adjustments accourding to height of the athlete and grip height, It (as far as I was concerned) eliminated any improper assumption that I could possible make.

I just measured Tim's pole angle at take off during one of his practices and It's very close to 28 degrees. For what it's worth..

[dj]

good morning

don't believe anyone has been pushing "just try it it works". what i have been trying to explain is the "physics".. application of force.. speed.. and how that speed is related to grip.. and how speed is related to stride length and stride frequency..

you don't have to try it at all.. but i would think that before you can comment with "athority" you would have the common decency to investigate the truth. and if you investigate and find the truth, you can explain it better.. because i'm having a hell of a time explaining something that is sound based on the physics of the event.

not only does it fit the application of force... speed down the runway... it has an accuracy factor that is invaluable in the pole vault..

the only negitive i have ever found in 40 years is that an athlete that can't run fast… doesn't want to be told they are to slow to jump high. if they want to jump higher they will work on there run..

I think slickvt knows how to pole vault.. and the only thing he needs to do to jump 5.50 is get a faster better run that would put him within the parameters of the chart.

does the run make you a vaulter? no.. but the world record holder has the fastest run. and the matching lengths and frequency of strides that match the "Chart"

you have made some extremely "childish" remarks, without knowing you i thought you where above that..

can anyone explain if and how it does or doesn't fit newtons laws of motion? maybe that could get rid of the "myth" tag my data has seem to obtained.

dj

[PVstudent]

Volteur.

The assymmetry you note in the respective step lengths and rates is not galloping (that is if I understand your human galloping rhythm suggestion correctly) but is a function of the pole carry and the trunk involvement in initiating and progressing the plant through to the last step.

There is also evidence that there is some step length assymmetry in the mid phase of the approach run (see female case study data chart and the male case study 5.30m jump).

The differences are small but can also be associated with the pole oscillations and the rate of pole angle change entering on to the final 6 steps of the approach.

A low angle of pole carry and a low bottom hand increase the degree of right and left step length differences in some individual cases. I have also found that an overly wide grip hand separation increases the assymetry.

The differences refered to are small. Assymetry of left v right side step lengths, you are quite right have been observed in other running take-offs. I am very hesitant to call it galloping.

In the context of pole vaulting it has important functional significance in respect to timing and synchronizing of the arms and legs with pole carriage and plant actions.

I base my comments on observations and measurements made from video recording, on practical coaching and making direct measurements on the runway.