take-off point

[Pogo Stick]

As any righteous brother who worship apostoles of the modern pole vault know, correctly performed free take-off provide short period of free flight without any resistance from pole. During this period you can do whatever you want without penalty in energy loses and your horizontal and vertical speed remains preserved.

Where exactly should be take-off point for free take-off (pre-jump)? Is that at vertical line from upper hand, or maybe 1 inch or 5 inches back? I did not find any info about this, but it should be around vertical.

How can we add more time for free-flight?
Simply - by moving take-off point back. Pre-jump with take-off point 30 cm back from vertical line (approx. one foot), with 20 degree take-off angle and 9m/s horizontal speed after take-off, will provide 2 hundred of second longer free flight without pole resistance and 10 cm (4") higher COM (Center Of Mass). Actually even more, but this should be very good approximation.

What we can do with all this additional time?
I don't know I am not coach. It is just few hundreds of second, but higher COM and bigger pole angle (1.5-2 degree) can be useful. Maybe vaulter can lower forward leg and start swing with both legs and lower COM (relative to upper hand)?
Bad thing is that your body need to travel longer to reach pits - can you improve your best long jump for whole feet just like that?

[powerplant42]

SWING!!! And an entire foot is a little too far out, if that's what you're saying we should try to make happen...

[KirkB]

You can't swing yet. You can't do that until the pole hits the back of the box and gives you some resistance to swing against.

The gap that Pogo is asking about can be filled by stretching your top hand higher up (and forwards), and stretching your trail leg further back. And maybe more. In other words, complete your "jump".

Lowering your lead knee during this "free takeoff" or "pre-jump" is also not something that you should do. Pogo, I don't think you really meant that, as it's near-impossible, and totally futile. Those vaulters that drop their lead knee shortly after takeoff do so AFTER the pole hits the box - not before. If you were to do it before, then you wouldn't be finishing your jump. Furthermore, for the two-legged swing to be most effective, it's the actual DROPPING of the lead knee that puts more energy into the pole. If you've already dropped it, then this energy transfer is lost. Two-leggers still need to drive their lead knee forwards to finish their jump - albeit most don't do this very well. This whole paragraph is just to clarify why dropping the lead knee so early is not only impractical - it will never happen in practice, not even by intent. Enough said.

I have never personally experienced a two-legged swing in a competitive vault on a pole (although I have on gym equipment) so I don't claim to be an expert in that technique.

"And maybe more." You may have noticed that I haven't mentioned what I personally would do during this short time period between leaving the ground and hitting the back of the box. I filled that gap quite effectively in my Bryde Bend technique. You will find the answer in the Bryde Bend (Jump to the Split) thread.

Kirk

[powerplant42]

If the take-off is finished as completely/forcibly as possible (without losing control of course), it's impossible really to start to swing until maybe a tenth after the pole tip has hit the back of the box... however, one should only try to jump hard off the ground, then swing hard. Anything other than this could waste time in the jump. I can't seem to understand why anything should be consciously attempted during this short point in time other than trying to swing. I believe that forcing the trail leg back is a waste of time/energy in the vault (not a personal attack on the Bryde Bend, just what I've come to believe...). Let me explain why: If one tries to force something like this, they can still only gain a small amount of additional 'lift' or 'backward thrust' (whatever you want to call it) of the trail leg. In the perfect jump, I believe that this is what happens, but we humans are far from perfect; our bodies do not react as fast as we need them to in order to jump perfectly. The time it takes for the pole to hit the back of the box after the toe leaves the ground is only a few hundredths of a second. If one tries to do anything like lifting the trail leg back, the brain will tell the leg to do so and contract as quickly as possible. But the problem is, is that by the time the brain has finished sending the signals to lift the leg and has begun to tell the leg to come back, the pole has already been in contact with the back of the box for a relative eternity! Lifting the leg purposely exacerbates the problem of not enough time in the vault to do what we want to already. The few extra psi in the leg will not make up for the lost time in the jump. This is my opinion, and I'd be willing to change it if you give me some good scientific evidence that says otherwise. In fact I would be quite happy that I learned something about the delicate intracies of the pole vault, not to mention very impressed. Until then, I'm a big proposer of the NATURAL tendency of the trail leg to come back a little through jumping off of the ground forcibly being enough, NOT forcing the leg back. Please, change my mind. It is very open to new knowledge!

[Pogo Stick]

You can't swing yet. You can't do that until the pole hits the back of the box and gives you some resistance to swing against.

The gap that Pogo is asking about can be filled by stretching your top hand higher up (and forwards), and stretching your trail leg further back. And maybe more. In other words, complete your "jump".

Lowering your lead knee during this "free takeoff" or "pre-jump" is also not something that you should do. Pogo, I don't think you really meant that, as it's near-impossible, and totally futile. Those vaulters that drop their lead knee shortly after takeoff do so AFTER the pole hits the box - not before. If you were to do it before, then you wouldn't be finishing your jump.

I agree with you. You can't really do anything with forward leg in just few hundreds of second. The biggest benefit of such early take-off could be higher COM at the moment of contact with box. It is like you just become 4" taller, or jumping from 4" platform. I can imagine a trouble with pole planting in the box - if COM rise faster than pole tip fall, you will miss the box.
It looks nice on the paper, but I am not expert in biomechanic, and I probably missing something obvious.

Furthermore, for the two-legged swing to be most effective, it's the actual DROPPING of the lead knee that puts more energy into the pole. If you've already dropped it, then this energy transfer is lost. Two-leggers still need to drive their lead knee forwards to finish their jump - albeit most don't do this very well. This whole paragraph is just to clarify why dropping the lead knee so early is not only impractical - it will never happen in practice, not even by intent. Enough said.

But what if you drive your lead knee as triple jumper - to hip level and with hold? It seems to me that Lukyanenko drive knee in that manner. This will reduce the time needed for dropping forward leg and maybe in that case benefits can be bigger than losses. I cannot provide any formula or proof for that. As I said, this is out of my area of expertise, but I love to play mind games.

[KirkB]

... one should only try to jump hard off the ground, then swing hard. Anything other than this could waste time in the jump. I can't seem to understand why anything should be consciously attempted during this short point in time other than trying to swing. I believe that forcing the trail leg back is a waste of time/energy in the vault (not a personal attack on the Bryde Bend, just what I've come to believe...). ...

If one tries to do anything like lifting the trail leg back, the brain will tell the leg to do so and contract as quickly as possible. But the problem is, is that by the time the brain has finished sending the signals to lift the leg and has begun to tell the leg to come back, the pole has already been in contact with the back of the box for a relative eternity! Lifting the leg purposely exacerbates the problem of not enough time in the vault to do what we want to already. The few extra psi in the leg will not make up for the lost time in the jump. This is my opinion, and I'd be willing to change it if you give me some good scientific evidence that says otherwise. In fact I would be quite happy that I learned something about the delicate intracies of the pole vault, not to mention very impressed. Until then, I'm a big proposer of the NATURAL tendency of the trail leg to come back a little through jumping off of the ground forcibly being enough, NOT forcing the leg back. Please, change my mind. It is very open to new knowledge!

Powerplant, these are all good questions/comments, deserving a scientifically sound answer ...

Somewhere in a post a few weeks ago (prior to the Bryde Bend thread), I mentioned that you can't expect to learn how to lift your trail leg cognizantly DURING vaulting practice or competition. You must learn this in the gym - with thousands of reps - until it becomes automatic. Then, when you Jump to a Split, your brain doesn't have to tell your legs what to do - your "muscle memory" does this instead. I think that's the scientific answer to your concern of how you can add an extra "step" (without any leakage) to an already complicated process that occurs in just a split second.

"Waste time in the jump"? This thread started with Pogo asking what to do with all the EXTRA time you had between the time you left the ground and the time the pole hit the box. If you have no gap, then you're right - there's not much time to "waste". But if you do a true "pre-jump" with a gap, then what ACTIVE (not PASSIVE) action can you do during that time that will add energy to your system? The answer is to quickly move your trail leg back/up, then quickly move it forwards/down. Please don't consider this a passive action - it's VERY ACTIVE. And the rewards aren't miniscule. Done right, you'll add more than a foot onto your PR! Well worth the extra training and effort!

Rather than try to explain this scientifically, it's more convincing if you just try it on the rings or high bar. From a hang, do a one-legged "Hinge. Whip. Hinge. Swing." (If you don't understand those terms, read the definitions that I posted today in the Bryde Bend thread.) Now do it again, but this time, ask a buddy to hold your trail leg ankle about a foot back/up from a dead hang. You should be starting the Hinge in a slight "C" position now. How much higher was your forward Swing that time? Now do it again, from about 2 feet back/up - with a bigger "C". And so on. You can also experiment with your buddy giving you a "tap-push" to start your Hinge. Once you feel the force that can be applied in the Whip, you'll convince yourself of the HUGE advantage of lifting your trail leg back - I don't need to.

Also, if you're doing this on the high bar, notice how much the bar bends. This simulates the extra energy that you put into the pole by a more vigorous Whip.

Caution: Remember that this is an advanced technique. Don't expect instant results when you first try it. The purpose of this expirement is only to explain the scientific principle behind the technique. Once you're convinced, THEN put in the thousands of reps that I recommend (or hundreds, if you're already an elite vaulter), THEN add this technique to your competitive vault repertoire. Not before! There's no silver bullet! You've got to do the reps!

Do me a favor - don't counter with another reply until you've actually tried this. If you don't have a genuine high bar readily available, find a chinning bar or "monkey bars" at a kid's playground, and go nuts! It will settle this issue much better than bantering back and forth.

And then:

But what if you drive your lead knee as triple jumper - to hip level and with hold? It seems to me that Lukyanenko drive knee in that manner. ...

Yes, the lead knee drive should be held UP, just like a triple jumper. But Lukyanenko doesn't hold it up - he drops it. This can be seen very clearly in his 6.01 video.

Kirk

[Pogo Stick]

I find out what's wrong with take-off point too far from vertical - you are losing vertical speed. At 1 foot (30 cm) you will lose approx 8% of speed. At the same time, wasting of kinetic energy is even bigger because the energy is proportional to the SQUARE of speed. That's means 16% less energy at the moment when pole hit the back of the box.
According to studies, vertical speed of COM is the most important variable for final clearance height. Higher COM and higher pole angle cannot compensate energy loses - they are related linear with energy, forces, etc.

[KirkB]

Pogo, please quote your sources (with links if possible), and show your assumptions and formulae. I can't follow your logic of how you "lose 8% of speed" then "SQUARE of speed" then "16% less energy". Your math might be correct, but without sources, assumptions, and formulae, I'd just have to take your word on it - which I'm not willing to do just yet.

I'm from Missouri. Not really, but that's how the saying goes when somethings unproven.

Prove it!

Kirk

[Pogo Stick]

I'm from Missouri. Not really, but that's how the saying goes when somethings unproven.

Nobody is perfect. I am carrying my own cross - I am engineer. :-)
And I made mistake: vertical speed loss is around 14% not 16%. :-)

Pogo, please quote your sources (with links if possible), and show your assumptions and formulae. I can't follow your logic of how you "lose 8% of speed" then "SQUARE of speed" then "16% less energy". Your math might be correct, but without sources, assumptions, and formulae, I'd just have to take your word on it - which I'm not willing to do just yet.

Prove it!

Kirk

We engineers often forgot that you ordinary people have trouble with math and physics. :-)

It is simple ballistic calculus:
http://www.znanje.org/i/i25/05iv04/05iv ... age001.gif (click at link for the picture - got error when trying to insert it in text)

α - take-off angle
v0x - horizontal take-off velocity
sx - distance from take-off point to vertical (point where pole contact back of the box)
g = 9.81 m/s2 (gravity constant)

Let assume the following:
α = 20 degree
v0x = 10 m/s
sx = 0.3 m (roughly 1 ft)
Let also assume that air resistance is zero. Otherwise, Fluid Mechanics and Aerodynamics need to be used. This will simplify calculus and will not influence accuracy because the distance is very short.

We need to calculate the following:
v0y - vertical take-off velocity
t - time to travel from take-off point to vertical (0.3 m horizontally)
vy = horizontal velocity after t seconds
vertical velocity after t seconds will be the same as at begining - 10 m/s (remember, we assume no air resistance)

Calculations:
v0y = v0x * tan(α) = 3.64 m/s
t = sx/v0x = 0.03 s
vy = v0x * sin(α) - (g * t) = 3.13 m/s

vertical speed difference: vy - vy0 = 3.64 - 3.13 = 0.51 m/s
That's 14.12% decrease from initial vertical speed - Q.E.D.!

[baggettpv]

I explained it perfectly well on my DVD. You can see the short presentation on youtube. Just search for me (rick baggett) and it's there...

You know who

[KirkB]

Pogo, I appreciate your diligence on this.

I had to search for QED on the Urban Dictionary, and here's what I found:

7. QED
What someone writes when insecure about his abilities as a physicist or mathematician to make themselves feel smarter than they likely are. Typically used by douchebags who think they are doing something amazing by proving a problem from a textbook. Usually follows a terribly formed proof which lacks rigor or reasoning.
"x+y=2. Clearly, z=4, QED."

"You're obviously incorrect, as is seen without proof. QED"

There were other variations to the definition, but I like this one the best! ha! ha!

Actually, I'm willing to give you the benefit of the doubt now that you know what you're talking about. Now I just have to recall my high school physics, and try to digest what this means. Maybe I'll take a look at that vid that Baggett's plugging. That might save me from cracking open the physics book.

So does the formula prove that a takeoff further back than vertical is inefficient? Petrov as much as says so in Appendix A of BTB2, but why then does Bubka think that getting a bit of airtime on takeoff (i.e. a pre-jump) is good? You can't get this airtime if you're under or vertical, so the only way to get it is to be out a bit. From practical experience, I'm in the camp that thinks being out a bit is good, but I'm willing to try to understand the science behind this, and to listen to other opinions.

Kirk

[Pogo Stick]

Pogo, I appreciate your diligence on this.

I had to search for QED on the Urban Dictionary, and here's what I found:

7. QED
What someone writes when insecure about his abilities as a physicist or mathematician to make themselves feel smarter than they likely are. Typically used by douchebags who think they are doing something amazing by proving a problem from a textbook. Usually follows a terribly formed proof which lacks rigor or reasoning.
"x+y=2. Clearly, z=4, QED."

"You're obviously incorrect, as is seen without proof. QED"

There were other variations to the definition, but I like this one the best! ha! ha!

Actually, I'm willing to give you the benefit of the doubt now that you know what you're talking about. Now I just have to recall my high school physics, and try to digest what this means. Maybe I'll take a look at that vid that Baggett's plugging. That might save me from cracking open the physics book.

Don't mess with B.Sc. of EE. :-)
If I just had as many hours of pole vaulting as math and physics drills, I will be world champion. :-)
Now, my diploma is not even worth the paper it is printed on... but this is another story.

Q.E.D. is "an abbreviation of the Latin phrase 'quod erat demonstrandum' (literally, 'that which was to have been demonstrated')..." (Wikipedia)

I just love Latin phrases, on our pit cover I wrote "Hic Rhodus Hic Salta" - which is Latin for "Here is Rhodes, jump here!"

Very interesting explanation of this phrase can be found here: http://www.marxists.org/glossary/terms/h/i.htm
Don't be scared of the word "marxist" - Agapit, Bubka, Petrov, Markov, Parnov and myself lived in marxist-communist countries and are still alive and well. The following quote actually shows that ancient Greeks were practicing pole vaulting:

The origin of this odd saying, whose currency is largely due to Hegel and Marx, takes a little explaining. It originates from the Latin translation: “Hic Rhodus, hic saltus” (“Here is Rhodes, jump here”), a traditional Latin translation [see, e.g., Erasmus, Adagia III.3.28] of the punchline from Aesop’s fable The Boastful Athlete.
The first mistranslation occurs in the translation from the ancient Greek to Latin. The name of the Greek Island is Ροδος (Rodos), but classical greek only had capital letters. Common Greek, with separate capital and lowercase letters was developed as a result of the conquests of Alexander, in order to make the language easier to learn among non-native speakers (which is when they started using accents in writing, to allow non-native speakers to pronounce words correctly). The quote comes from before Alexander’s time, and the word was ΡΟΔΟΣ (RODOS), hence the confusion, because the Greek word ροδος means “rod”, or in Latin “rodus,” which was used to refer to the long stick that athletes uses for pole-vaulting.

Whichever way the fable is translated, the story is that an athlete boasts that he once performed a stupendous jump, and can produce witnesses: the punchline is the comment of a bystander, who says that there is no need of witnesses, since the athlete can demonstrate the jump here and now.

So does the formula prove that a takeoff further back than vertical is inefficient? Petrov as much as says so in Appendix A of BTB2, but why then does Bubka think that getting a bit of airtime on takeoff (i.e. a pre-jump) is good? You can't get this airtime if you're under or vertical, so the only way to get it is to be out a bit. From practical experience, I'm in the camp that thinks being out a bit is good, but I'm willing to try to understand the science behind this, and to listen to other opinions.
Kirk

Formula just shows that ideal take-off point is exactly at the place when toe tip just leave the ground, and at same moment pole is just a hair thick far from touching back of the box. Only in that case there is no loses in vertical speed. If you jump too far from that point, the speed (energy) loses are bigger than potential gains. If take-off is way under, too much energy is going to ground instead to vaulter and pole. Please don't ask me to prove last sentence - I am not ready yet and probably will never be. It is just not so easy as ballistic.

Formula is (almost) perfect for explaining flight of cannon ball but is not perfect for humans because, as powerplant42 said, humans are not perfect. It shows that ideal take-off angle for achieving maximal horizontal and vertical distance is 45 degree. Lot of studies shows that take-off angle should be around 20 degree for pole vaulters. Even for shot put, this angle is around 30 degree.

That does not mean you cannot jump 20ft if you are 1ft under or 1ft out and your take-off angle is 15 or 25 degree, but it is highly possible that you will never jump 21ft. As Agapit like to say the energy efficiency is the key. No passive phases and no unnecessary wasting of energy.

My experience is telling me that there should be a sweet spot where free take-off advantages like full stretching of body and taking better preparation for swing are more beneficial than small losing of vertical speed. This is probably what Bubka means.