Mid Mark Chart

[CONNEXE]

Human beings are extremely complex. There is no absolute truth in training methods and models.
Technical or training solutions rejected as nonsense may resurge 20 years later in a slightly modified version as miracle recipes.
Records and championship titles are remembered. Those who ruined their health by inappropriate training or wrong technique are forgotten.

A coach may be famous:
- because he is a good coach,
- because he can explain his ideas better than other coaches,
- because he has a great reservoir of talented youngsters to select from,
- because he can convince great athletes to join his group,
...
- because he knows how to use illegal tricks without being caught.

When an athlete realizes that his coach is not so good it is most often too late - but there are other healthy youngsters to take his place.

Athletes are good because of:
- physical strength,
- psychological balance,
- great will power,
- good technique,
...
- use of illegal tricks without being caught.

Never all advantages come together. This is why the world record holder does not necessarily have the best technique.

A coach admitting (or luring) an athlete in his group usually wants this athlete to improve. He risks his reputation if the athlete fails. He should therefore not be called a fraud.
An abandoned coach finds himself in an uncomfortable situation. It looks as if he is accused of incapacity. Understandably he is annoyed.

Nevertheless, the MID-chart allowed some very interesting discussions.
It certainly is of great help for not so experienced coaches to remind them of the danger of overstriding.

From my own observations the chart is quite right for medium to high level male vaulters.

I have however found great deviations for medium level female vaulters (up to one meter out). They are fast running girls with a small bend.
With little bend you have to run much faster to get the pole to the vertical. Therefore, if you want to jump with a small bend, the MID-chart may not be for you.

[dj]

Each individual person has the right to make excuses or assumptions as they will..

But truth and fact can stand on there own..

dj

[ladyvolspvcoach]

Pvstudent, my apologies for not getting back any sooner on the issue of the video that I published a month or so ago. However, open heart surgery and associated complications has a way of taking the wind out of your sails. So that being behind me and several conversations with the Dartfish technical staff later and here goes.
First a preface, I do NOT consider myself one of the “big brains” on this forum. My sole motivation for cont, contributing when I do is to gain information or to attempt to help some other coach or athlete improve their skills and abilities when ever I can. That is exactly the reason that I coach. The model that I use began long before Bubka and Petrov in 1961 when the Rhode Island U champ taught me how to carry the bamboo pole that we got at the local foreign carpet dealer’s and how to slide the pole through my left hand when planting. Oh and using the pitchfork to loosen up the sawdust before we began jumping. So as the years passed and I watched the development of pole vaulting “models” I’ve kept up and adjusted over time……I must be getting senile with that little tirade.
In any case all of the data and frame rate translations that you proposed were used to make the video appear as it did, I’m sure are correct data and appropriate to the scenario that you were proposing. However, None of that applies to the video that I posted.
I video every practice using the same video and computer settings for each session. The two videos that I used in that particular video were among 40 or so videos of each of my athletes during that particular practice. Out of personal curiosity and a lengthy discussion with DJ, I synced up a couple of that days practice vaults in one of the Dartfish modules designed for that purpose. I was surprised at the result, because in each case they were running from 6 lefts (it’s early in the year still) and holding within a couple of inches of each other, and each of them matched up at the mid mark and through the last six strides you could not distinguish one from the other. So there was no theory intended to be advanced by publishing that video. It was a simple exercise that I did and thought would be a great visual for the thread. Was extremely surprised when an exercise ensued attempting to diminish the obvious visual of the video. So this is a video that was completely developed within the professional modules of Dartfish and not translated or reformatted for anyother purpose than that which was expressed. The video that was published was a wmv file that I converted the Dartfish video (avi format) to be able to publish it easier. So my friend what is seen on the video is exactly what occurred on the runway. What ever conclusions you may come to other than that is of course your option.
remember! Crainalanalitis has a sister desease . . . rectal octisis....I think there is a pill for that one but I'm not sure.....I'll research it...

[PVstudent]

ladyvolspvcoach on Fri Jul 25, 2008 9:49 am

In any case all of the data and frame rate translations that you proposed were used to make the video appear as it did, I’m sure are correct data and appropriate to the scenario that you were proposing. However, None of that applies to the video that I posted.

Are you saying that you didn't film at 30 or 60 frames persecond? Are you saying the accuracy of the timing was to 0.001second? Are you saying none of this applies to the video you posted? The scenario I proposed? What scenario? I wanted clarification of what was done so that I had some data to help me "understand" what I was seeing and to be confident in the possible "causation" underlying the very powerful impact of the video you put up. Also I might add, you said in a response to Agapit you couldn't explain it either.

I video every practice using the same video and computer settings for each session. The two videos that I used in that particular video were among 40 or so videos of each of my athletes during that particular practice. Out of personal curiosity and a lengthy discussion with DJ, I synced up a couple of that days practice vaults in one of the Dartfish modules designed for that purpose. I was surprised at the result, because in each case they were running from 6 lefts (it’s early in the year still) and holding within a couple of inches of each other, and each of them matched up at the mid mark and through the last six strides you could not distinguish one from the other.

What you put up is even more surprising then because the subjects were not gripping at the same lengths along the pole. Did all of the videos of the same athlete gripping at the same length along the pole in the same session also match up exactly? They should have done so exactly each time? Do they? Did They? They should if the video technique used in filming was standardized with respect to lens zoom factor, distance from the runway, panning rate and level, precise location of the camera on its tripod away from the runway, horizontal scale factor in each footage selected.

So my friend what is seen on the video is exactly what occurred on the runway. What ever conclusions you may come to other than that is of course your option.
remember! Crainalanalitis has a sister desease . . . rectal octisis....I think there is a pill for that one but I'm not sure.....I'll research it...[/

I think you may need to reflect objectively about whether what you see is exactly what occurred on the runway. If two vaulters are not gripping at exactly the same length along the pole but have the exact same 6 step approach and takeoff distance out from the rear wall of the planting box surely this weakens the claim in DJ's chart in regard to this relationship! There is a broad bandwidth allowable according to the chart which suggests to me that the variability factor leaves us with exaclty what we see here. How broad the bandwidth is varies from being very small at the elite level and very big the lower the level of expertise of the vaulter. Sometimes the vaulter's personal performance will match exactly from one trial to the next and sometimes it wont. Similarly for between vaulter comparisons at the same grip heights some times they will match sometimes they wont. At the elite level the frequency of within vaulter variability and range of variability is small. Because at the highest levels of performance the variance in most parameters between vaulters is very small we would expect vaulters gripping at the same distance along the pole to have 6 step approach and takeoff distance to be similar. How similar is similar? Therein lies the problem!

Finally Ladyvolscoach, rather than resort to banal 'anal humour', I leave you with these words from Kiekegaard:

"Life is lived forwards, but understood backwards."

Go well and enjoy life because I assure you the sun will rise tomorrow despite our mutual inability to explain rationally what your marvellous video shows. In the meantime I will continue to search for knowledge as it is the raison d'etre of a PVstudent.

[ladyvolspvcoach]

pvstudent, in the spirit that you have defined your call sign as a pv student , I have gone back and dug through technical sheet user manuals for my camera to really ascertain the technical settings of the video that I use regularlly. However, there is little technical information available. There are certainly detaled descriptions on how to install the lens cap, but little or none on the settings that I use.

I did find that my camera has a recording range of 1/250 frames per second to 1/4000 FPS. I use the Sport setting which is 1/4000 fps. I set the tripod (same one each time so the height settings don't change) on a premarked spot in the indoor facility. Location is the same everytime. I hook up the computer to the camera directly and use the "In the Action" module in Dartfish. Each jump is recorded as a seperate clip using all the exact same settings. The clips are captured in real time directly within Dartfish on the computer not on tape. So all the video are on my harddrive at the moment they are created. I then go to the various modules within Dartfish to study them and see what I can see using the more sophisticated tools of Dartfish. That is the source of the movie that I posted.

As for the different grips of the two athletes. They are holding within an inch of each other from tip to grip. However, the shorter girls was in her second year of vaulting and capping a 12' 120 Spirit at the time. the other athlete was grip about the same on a 13' 135 Big Stick. So eventhough the poles were different specs the grip heights were essentially the same.

I will go back and review Agapit's question and revisit my answer. At that time I wasn't doing very well health wise and some days I just didn't have the energy to "get into it" . I consider Agapit a friend and will revisit his question and my response.

[dj]

hey

one of the things ladyvol showed me with dartfish was how two athletes would have the same frequency but different SIX sTEP MARKS..one longer one shorter.. for example bubka.. 57 feet tim mack 55 feet.. if you didn't know the six step marks you woulld think tim was running as fast as bubka.. but bubka was covering more ground in the same time.. something like 1.37 seconds for the last six steps..


the bottom line was that human potential was very simular in steps per second,, frquency.. on the same surface that is... it was the amount of force that gave the longer stride lengths.. there ground times were also very simular .. again indicatiing it was the force creating the stride length.. tim has a longer inseam than bubka so it wasn't "longer legs.. longer steps.." that is a miss conception..

dj

[altius]

I had vowed to stay away from technical discussion on pvp and I specifically had vowed to make peace with you dj. So I am not going to get involved in the technical discussion except to say that I have never used a mid mark chart - yours or anyone else's - with my athletes. I am not going to get into any debate whether I should have done so or not -as far as I am aware neither Petrov nor Parnov use them. However you will find that I have never commented negatively on the use of such charts - if they work for other coaches and their athletes that is great but I have not felt the need to use them. Despite this the evidence is clear that in Adelaide we did not have problems with developing effective run ups or using stiff poles -ie young athletes vaulting on poles 40 pounds or more above their body weight from 16 steps.

[PVstudent]

Ladyvolscoach

Thank you for going back to the technical sheet user manual for your camera.

That your camera has a recording range of 1/250 frames per second to 1/4000fps is indicative that you are claiming to have used an extraordinarily expensive and sophisticated video camera.

If you had said that your video camera could used lens shutter speeds of 1/250 second to 1/4000 second ie the exposure time per frame of video is at a time of one two hundreth and fiftieth of a second or at the sports setting 1/4000th of a second exposure time I would believe you.

I think you may have confused exposure time per frame with video frame recording speed which in the NTSC standard are nominally 30, 60, 120, 240 etc. frames per second. Most commercially marketed digital video camera models of the last decade would use 30 frames per second recording speeds. High speed digital video cameras for the scientific research end of the market were also available, but extraordinarily expensive. You may have had ready access to and the technical knowledge to operate with such a camera! Supply of the manufacturer's video camera make and model number of the camera you used would clarify beyond doubt that you had a camera of the sophistication and recording levels you suggest.

I think what follows is much more likely to be the case if you did not have a camera capable of operating at 250 - 4000 frames per second. The video supplied by you to PVP appears to me to have been recorded at 30 frames per second with an exposure time per frame of 1/250th of a second ( there is still considerable perceptible blurring in the individual images). I am open to being corrected on this point as you possibly will still have the raw footage available on the hard drive of your computer and you should therefore be able to check out the video recording frame rate and the exposure times per frame that were actually used.

In high speed sports where movement appears to be blurred at the standard recording rate of 30 frames per second a single frame exposure time of 1/4000th second reduces the blur. However, and this is important, a time of 1/30th second (1 / 29.97th second to be more precise) elapses between individual complete video frames (or 1/60th second per video field - each individual frame made up of 2 video fields) at 30 frames per second in the standard digital video recording mode.

Recording direct to a computer does not change any of the above. When you use the the more sophisticated tools within the modules (Simulcam?) of Dartfish, for a recording speed of 30 frames per second the best resolution that you can achieve in matching videos is +/- 1 video field ie 1/60th of a second (correct me here if I am wrong ).

Hence, if in the synchronizing process the videos you were 1 field out (the most conservative estimate as opposed to one frame out which would comprise two video fields) in identifying the touch down for the takeoff in matching the tapes i.e. 1/60th sec (0.01667sec)would result in there being between fields :

at 8m/sec (average speed of vaulter) a real space physical distance difference of 13.333cms (Or 5.25 inches);
at 7m/sec (average speed of vaulter) a real space physical distance 11.67cms (or 4.6 inches);
at 6m/sec (average speed of vaulter) a real space physical difference of 10cms (or 3.93inches).

In other words the highest degree of synchronizing accuracy is somewhere about 4 to 6 inches in real space physical horizontal distance depending on vaulter average speeds in a video of the vaulter recorded at 30 frames per second.

This is why it is not possible to claim exactness with repect to the video you put up! The Dartfish tool is a vey valuable tool for making qualitative and some limited global quantitative comparisons between performers when standardized recording and analysis proceedures have been followed.

The above is not intended to discredit what you put up, the video is startling and stimulating in regard to the six step mid mark discussions. What readers of the discussion need to be aware of is the limitations associated with the production of the video so that they can be better placed to evaluate it as objectively as they can.

I acknowledge that you now have indicated the girls were holding the pole "within an inch of each other from tip to grip". So if you have more video on your hard drive of either of the two girls and use the Dartfish "Simulcam" module to compare the vaulter with herself at this same grip height and 12 step run (6 lefts) how close is she on each match up in regard to step 6 mark out from takeoff, step length and rate. Remember the videos are according to your methododology "synchronised " to "toe off at takeoff". I will be fascinated to see the results since they should only bolster the mid mark chart case as to the invariance in six step mid for the individual concerned let alone in a comparison to another vaulter.

Thank you for seeking to clarify responses to my questions and in attempting to unravel understanding of what the video you put up actually shows and the accuracy with which it is possible to do so!

[Split]

Am I the only one that can't see the chart?

[rainbowgirl28]

Am I the only one that can't see the chart?

I am working on going back through and editing all of the posts that got truncated in this thread, and I will be deleting all of the snarky and rude comments.

[VaultPurple]

Earlier I posted asking how the mid mark chart would change based on a vaulters height and DJ said it didnt matter because stride length was based on speed and not length.

My question is how come Bershawn Jackson who is about 5'7 runs the 400ih in 47.x while taking 15-17 steps between each hurdle, while Kerron Clement who is 6'2 runs the 400ih in 47.x while only taking 13 steps between each hurdle?

If speed is responsible for stride length, then why can't Bershawn jackson run 13 steps between each hurdle?

[powerplant42]

Style... I'm sure if you asked him to, he could do it and still run sub 50. I've given up on understanding this argument, and I will not try again until I am probably 10-20 years older. For the most part, it's becoming near comical, and the biasness is incredible from both sides. The only one I see who's taken a true scientific, unskewed approach to this argument (and who has contributed a considerable amount to the topic), THE WHOLE WAY THROUGH, is pvstudent, but I have not read this whole thread, and I probably never will. So take it for what it's worth.