The PREJUMP : key to success or giant hoax

[BigStick Club]

Ah...and on a semi-related note...wasn't the box in Helsinki special in that it* would record all sorts of data?

*EDIT: changed to 'it' from 'in'

[agapit]

Ah...and on a semi-related note...wasn't the box in Helsinki special in that in would record all sorts of data?

It would be nice to get these results. The draw back is that the results were low for men’s. Must be weather. However, women did very well!

[Mecham]

How do you think the information would look? Weight measurements over time? Or what?

[agapit]

How do you think the information would look? Weight measurements over time? Or what?

If the box is synched with a high frame video you could get the layout of energy input over the whole jump.

if the box is not synched with a video you would not know the speeds of center of gravity during all phases and so information will not be as valuable, but still valuable enough compare to not having any information.

The tenso box can tell you about energy input during the second phase. The data is usualy presented as a curve describing the resistance force distribution during the inversion. The nature of the curve (distribution of the resistance) has the tremendous value. However, like all measuring equipment the error be must be small enough so the data is valuable.

[ADTF Academy]

Agapit Wrote:

"If you are able to takeoff and have a time after the toe leaves the ground and pole hits the back wall of the box you are griping too low. The goal is to avoid loses of energy and maximize the takeoff angle (not angle between the pole and the ground but the center of gravity vertical component). The pole angle will increase as a result of the larger free takeoff angle, but in any case time between tow takeoff and pole contacting the wall is not an advantage."


First off the timing difference here between the free takeoff and the prejump is potentially fractions of a second. Secondly, like any technical term there is a finite mark when people take the term in an overboard manner. Hence Prejump meaning hanging in the air for some crazy time till the pole strikes the back of the box so that the individual can reach maximal vertical lift. For me this is not the focus of the term prejump. I could be wrong for others.

I will agree as all the research has shown horizontal velocity at takeoff should be more the vaulters concern than vertical velocity, but vertical velocity and lift need to be address because no one can carry the speed needed for an ideal vault with a 0 degree takeoff angle it is physically impossible.

Now let's go back and address the notion of the focus of the prejump is the sense of hanging in the air to reach maximal vertical lift before the pole strikes the back of the box. I would be bold in saying this would in fact increase the pole angle and COM angle at takeoff to its greatest degree, but would limit the amount of horizontal velocity you could carry into the plant and thus limit your ability to rotate the pole (roll it over). This is because your focus would be on vertical velocity instead of horizontal velocity. Sorry to say when one increases the other must decrease proportionally. Now I know someone will come out and say studies have shown one athlete had the ability to maintain horizontal velocity during a slight increase in vertical velocity. Well more power to them it is not the norm. It can be trained but is not the norm.

However that is not what myself and I beleive others are talking about when they use the term PreJump. For me it means the fraction of seconds just after the toe has broken contact with the ground in which the body has just gone into free flight that makes up the notion of the Prejump. Otherwise everything is the same as that of the Free takeoff. The body posture and position is the same. Now I could be wrong here but I don't think the force of gravity has changed in the past month or two.

Therefore, (this is the key point to this post) if the same supposed goal takeoff angle of the athlete is used for a "Free takeoff" and for a "Pre Jump" (in my sense of the term between .001 and .03 after breaking contact with the ground) the vertical velocities would be near exactly similar as well as the horizontal velocities would be the same. Now this would depend on how many decibels you want to round off too and exactly how long after the foot break contact with the ground.

Now without having concrete data in front of me I would be bold to say as an educated guess anything longer than 5 tenths of a second of flight time is to long. (This is a study I must do now simply because I am curious as well.) Now you say how can they be very similar. Well you have the same supposed takeoff angle. You are carrying the same speed into the pit. And gravityand wind resistance need time to slow your horizontal/vertical velocity down and at least say .02 of flight time that is not very much at time to lose a lot of horizontal speed unless you didn't have much to begin with.

Now then what is all the hype over the Pre Jump. All it does or will allow is that at the moment of impact the angle the pole is to the ground will be ever so greatly higher (depending on the flight time before the pole strikes the back of the box) than if it occured just prior to breaking contact. Another study for each athlete would be to find out how much flight time is to much. For one person after .05 they might still be carrying nearly the same vertical velocity, but I gaurantee their pole angle and COM will be higher than when they were in contact with the ground.

Now how is this advantageous. I think all I have to say is who has an the advantage a taller or shorter pole vaulter. Does a 6 foot 3 inch vaulter have the advantage or does a 5 foot 8 inch vaulter? Is 7 inches really that much?

Now we always here it, "then coach why don't we try to obtain maximal vertical lift. I have a vertical of 32 inches." Well once again if the focus is only on vertical velocity there will be no horizontal velocity. Thats why their is no perfect takeoff angle for all vaulters. Every individual is different based on the speed you can carry, your reach, your weight and hundreds of other variables. This is why a lot of studies have concuded that the long jump takeoff is similar because even they realized a 45 degree angle though ideal for missles was not possible in jumping. So it is much less than 45 degrees for that reason to maintain greater horizontal velocities.

Now I will be once again bold enough to say this though. If you do find your ideal takeoff angle and you can do a prejump of no longer than lets say .03 hang time and you can master the art of correct body posture and positioning. I will go out on a limb and say that one your inflight rotation to vertical will be slightly quicker thus giving you more time to beat the pole to vertical and secondly the poles rotation will be slightly easier allowing you to maybe moving down a few more flex ratings to a stiffer pole.

However this shouldn't be the concern of a novice/highschool vaulter heck I would say not even for a decently good college vaulter. We can talk about this all we want but right now we don't do the things needed to even come close to perfecting this. It is simply something to talk about late at night.

If you can simply get an athlete or yourself to get a tall plant have romotely good posture at takeoff. This coupled with being able to carry as much controllable speed as possible into the plant and come as close to acheiving a Free takeoff/Continous Takeoff/Pre Jump as possible than you will be better off than 85% of those highschool athletes you will face hands down.

Half the battle of perfection is finding the easiest way to get there. Take your heads out of the clouds and start building the ladder to get there one peg at a time.

Thats why coaching is an art and a science. You never know whats behind door #2.

[altius]

Right on Spence! But unfortunately folk keep on trying to reinvent the wheel - they don't read the previous posts on this topic - or those on the Free take off and it seems that not many have read Chapter 23 of BTB which lays this issue out pretty well. But thats life.

Re the possibilities for young athletes - if I can find out how to put video up it may help clarify the issue - any ideas - what do I do?? Remember I am technologically challenged. Hope to see you in Reno.

[cdmilton]

Posted For Altius. Click on the link for a larger image.

Hope you can make something of these stills -could not manage a video
-perhaps next time. There are two shots of jamie scroop (bright green and
gold uniform) taking off to make a clearance at the world youths champs in
Sdbbury at 3,80 - but may be from two different jumps. jamies was 15 and
had been jumping less than two years - probably 80 training sessions.
cetainly dos not take off under -free take off??

Two shots of Tom Lovell 18 - at and just after take off in a 5.00 mclearance
at trails for world juniors in 200o. Looks like a free take off -jumping
4/5 years

Two shots of Patrick Jesser -19 - Taken from Commercial TV- on his way to
5.40 clearance at Olympic trials in 2000. Looks like free take off.
Jumping 4/5 years.
--

One shot of Wendy Young -19- on her way to 4.40 clearance in Aus grand prix
meet March 04 -looks like a free take off.


One shot of Chris Lovell 18 - Left hander - on way to Five m clearance - not
quite a free take off!

Not professional athletes - but introduced to a good technical model from
day One.

[altius]

Thanks Chris!! .

Readers please note that this post is only an attempt to counter the apparently common view that only superstars can develop the capacity for a pre jump or even a free take off. If nothing else these images should confirm that ordinary kids can begin to work towards a pre jump and can manage a free take off on occasion. Equally important they did not take off under, and so generally set themselves up for an active whip of the take off leg in the second phase etc etc.

I pray that they do not set off the "my kids hve jumped higher that your kids" syndrome so prevalent in the coaching world. So please note that I am NOT saying these young athletes were superstars - only that their techniques, at least in part, can stand comprison with those of many of the great vaulters of recent times and represent an ATTEMPT to master a clear technical model..

There seems little point is allowing a youngster to spend five years or more developing poor technique - and then when it becomes clear that they have REAL talent - teaching them - or attempting to teach them - how to jump efficiently.

To She who must be obeyed - please note that Jamie used the Petrov approach to the pole carry, drop and plant ; as you will see, if I ever get a clip to Chris -and of course if anyone else is interested.

[dj]

ADTF academy.. makes good points..
We have to find a way to practically apply the “physicsâ€Â

[MightyMouse]

That makes sense, especially on how to train for it

[master]

i consider the prejump as a subtle penultimate, very subtle, without lose of horizontal speed..

Hi dj,

Can you help me understand how you are using the word "penultimate" in your post? I thought the word meant "next to last" and in vaulting referred to the last step before the takeoff step. The word has been used in other posts I have read and I didn't understand them either (based on what I think the word means.)

Thanks.
- master

[altius]

DJ - note that the essence of Bubka's responses in Jamaica is in BTB Chapter 23 and the full transcript of that session is posted on beginnertobubka.com.

In fact I was the one who asked him the key question about the pre jump take off specifically because -as i said that day - many folk had indicated that I was off my rocker to think it was possible to be in the air before the pole tip hit the back of the box. Bubka immediately responded that i certainly was not stupid because that is what he TRIED to do on every jump - however it was very difficult and he therefore only managed it occasionally. However note that i had already asked him the same question - and received the same answer - in a private discussion with him in September 1990. My question in Jamiaca was intended to get his reply into the public domain.

Agapits post here or elsewhere indicates why this is so difficult to do consistently - however given that long jumpers find it difficult to hit the board accurately - without having to worry about controlling a long lever - it is pretty obvious that vaulters are going to find it difficult to nail the take off correctly every time. As I argue in BTB - even an attempt to pre jump will improve the take off.

Introducing the notion of a 'pre jump' take off - the term I coined after meeting Petrov in 1985 - to describe this action - is easy . It can be done with two/4/6 step take offs on grass. in a sand pit and of course onto the pad. However as the run gets longer and faster it is obviously more difficult -especially if the run up is not properly structured.

The stills above show young athletes of no huge talent or training age getting close to a free take off.

Dima Markov can be up to one foot in the air before the pole tip hits from eight steps - while on a full run he may be one inch in the air - as will be seen in many of his jumps including his 6.05 in Edmonton. However the best photo I have ever seen of a pre jump is the one of Bubka we put on the inside cover of BTB as he takes off for the first 6.00meter clearance in history.

Master - 'Penultimate' definitely means the last but one -as ultimate means the final one! The devils are my grandson Matthews idea not mine!