this is "sort off' the grip... but it's too late in the vault and the elbow is not out....
i would tend to think that.. yes he is stabilizing/guiding with the left hand.. but also since the left elbow is not out i would think he is using it as a 'fulcrum" from the force being generated from a strong trail leg swing... and.. he may be "intuitively" pressing slightly with the left/lower hand to keep the pole bent and moving.. medal re-shapes itself (as do some pole patterns) faster than glass.. so it is logical, and physics.. for each action there is an equal and opposite reaction.., if the pole is "pushing" to straighten, the vaulter is "pushing" to resist until he can get in position to exit the pole where he wants to go.. in this event (pole vaulting) that is vertical... same reason we have "tuck and shoot" as a technique.. the vaulter spends and "un-equal" amount of time on the "load" or the penetration phase and has to "tuck and shoot" to catch up... has to use stiffer poles because of the “force” on the bottom.. uses a bigger pole to keep from blowing through and ‘force” bends to use the bigger pole.. and the cycle repeats itself until we have a “technique” set in place.. just like the knee drop/pump. Physics should win most times.
the takeoff.. is the most critical juncture in the vault… and Alan I’ll give you credit for trying to beat everyone over the head with a “free” takeoff.. BUT it’s not just “free” that makes it correct. George Moore, in the 70’s when Bubka was ten, said (not his exact words.. I need to find the article) that the transfer of momentum from horizontal to vertical at the plant/takeoff is the most important part of pole vaulting. If an athlete can’t master the plant/takeoff he will never be world class.
I have been going back over the ‘science’.. a couple of Tully vaults and a Bubka vault. Interesting comparison, they have the same speed on the last two steps.. Tully’s COM was slightly higher at plant, Mike was taller. Mike was way “under” for him.. Mike and Earl averaged around 2 to 4 inches under, Mike was more than that according to the “science”.
Even though Mike’s COM was higher at the plant.. the next instant (frame), of extension of the top arm, Bubka was higher!!! Mike was under and had gotten “snatched” from the ground.. but at the next frame, instant of takeoff (toe leaving the ground) Mikes pole was bent 1% and Bubka’s 1.6%?? Bubka was under by 10cm/4 inches. The rest of the swing, after they were off the ground, was.. tit for tat…
Interestingly on Mike’s jump, partially because he was under he had a lower takeoff angle, 11.6 degree, and bent the pole 33%. His grip was 4.99 and he still cleared a 5.80 bar with a max COM of 5.85.
Bubka cleared 5.85 with a grip of 5.10 and a max COM of 6.12m a TO angle of 16.4 degrees and only bent the pole 27.1%.
Next… I have a 5.70 jump of Tully, under by .15cm (only 2” more than the Bubka jump) a grip of 4.87cm and Max COM of 5.85 (higher than the 5.80 jump with a lower grip!) His angle of takeoff was 14.7 degrees and pole bend was 28.5%.
First of all he was on the SAME pole.. same flex!!… don’t jump to conclusions… yes he was one grip lower which would “seemingly” make the pole stiffer.. but honestly not even close to the degree that YOU are thinking.. the way the pole was made that would only put the top of the grip 2” closer to the “mid point” of the sail piece… minor to the real picture.
It was the WAY and where he took off. In discussing the “free takeoff” I have always gotten that we are talking about the “where”, always, and not the how.. until you have done the math, studied these numbers…( and I haven’t “studied” them enough or pulled them out since 1988.) thrown out your/my own “biases” created over a 40 year coaching career and put it to a test.. you may be closer but you still may not “get it”.
I have the utmost respect for the scientist that give us this information and they are at the top of their field. They can help us “draw conclusions” and get us closer to a “final answer” but unless they (us, coaches included) have actually jumped at a world class level or coached athletes that have, we will not get close enough.
Petrov and Bubka can if we match the science to their practical knowledge and “feel”. I have been fortunate to work reasonably close to 3 world record holders and/or their coaches and a gold medalist.
I have sat in the floor with Mike Tully with the “numbers” spread out on the floor. Going over each, deciding where the focus should be first, the meaning of the numbers by his “feel”, physics and his athletic ability.
Honestly we have never had a “conference”, that I know of, where the science met the athlete and it was accepted by the majority and bias or ego didn’t get in the way and kill the effectiveness of the event. Mike Tully (the absolute best “test pilot” before Bubka) went to some sessions but he was never going to “share” to much, first because he wanted to beat you and second there were always those that “had a better way”.
I know Tom Tellez had it right and worked with several of the top vaulters in the world at the time. I know Guy Kochel had it right with Earl and others he coached. I know Greg Hull had/has it right and showed that with Nick Hysong. I know Bemiller has/had it right.. I think at some point all of them, me included, got tired of the “brick wall” that didn’t follow the physics and have said, go ahead, beat your head against the wall…
Back to the numbers.. THE IMPLUSE at the takeoff is more important than the position. Yes the impulse is negated by an “under” takeoff by varying degrees.. but you must absolutely have an “upward” impulse at the takeoff to maximize your potential AND to know what size (and bend characteristics) pole to us.. AND size of pole based on transfer of the horizontal energy will determine the “technique” after you leave the ground.
As the toe left the ground, where Bubka, has 1.6% bend, Bubka’s trail leg toe was 2 inches in front (toward the box) of the top grip. Mike’s was 2 inches with 1% pole bend.
Mike had less pole bend at this point even though he had taken off a little more under than Bubka..
No real conclusions can be drawn from this frame without the “surrounding” physics/numbers.
Bubka’s pole angle at this point (toe leaving the ground) was 29.6 degrees, Tully at the same point 29.8 degrees..
Here’s some key info if we put it in context with all the data.. In first “lite” based on Tully jumping the same max COM, one with a lower grip and less pole bend, 28.5% to 33%, you might want to think that less pole bend is better.. and I have seen that thinking start to dominate the “masses” going back to Bubka’s later years.
This is not correct “thinking”, when you match the physics with the correct takeoff position, and that position is out and with a strong “up” impulse, you will not only bend (load) the pole correctly it will come “out of the bend” correctly with the athlete moving up as if they were catapulted up. A larger (30+ degree ish) bend is advantageous from a physics stand point .. IF THE TAKE-OFF IS CORRECT .. because you can grip higher and produce higher jumps with the same energy input.
A correct takeoff includes a penultimate. The ladies, Murer, on the vids that were just posted were not bending the pole very much, not as much as I think they should, but they also came off the top.. somewhat “flat”. I feel this ‘angle’ on top is not created because they didn’t swing back far enough but because they ‘stretched” the last step. They stretch the last step because they are out to far at the MID and can’t “get the feet down” to promote the “up” impulse that is needed. If they did that correctly they could bend more, grip higher and still “feel” the kick on top of the pole.
Tully bent the same pole 33% because of a bad takeoff but still cleared a 5.80 bar with a 5.84 COM. If he took off correctly with the same input of speed he could grip higher, maybe on a slightly bigger pole, still bend 31% and have the same proportions to grip to COM he had on the 5.70 jump. Which by the way is where we were headed in 1988 when Bubba saw Tully jump 19-2… Based on the math and the changes from the correct impulse at the takeoff and with the speed he already had we were looking at a 17 foot grip and a 20 foot + jump…
Of course the athletes, Bubka, included that were faster than Tully could use the same science and jump even higher.
One of the keys and variables is matching the grip and pole strength (flex –design) with the correct impulse and speed. Tim Mack was not a “pole squash’er” he matched the variables (verified by his height above grip) on his best jumps as good/better than anyone that has vaulted.
Here’s some numbers to support the “impulse” as the key factor. and a "free" takeoff Alan..
Tully.. 5.70 jump at take off.. toe leaving the ground (5.85 max height COM)
Horizontal Velocity of CG………7.61 m/s
Vertical Velocity of CG………....2.00 m/s
Resultant Velocity of CG………..7.87 m/s
Tully.. 5.80 jump at take off.. toe leaving the ground (5.84 max height COM)
Speed last two steps.. pen..9.56..last..9.64
Horizontal Velocity of CG………7.96 m/s
Vertical Velocity of CG………....1.64 m/s (remember he was under and “snatched” from the ground.
Resultant Velocity of CG………..8.12 m/s
Bubka .. 5.85 jump at take off.. toe leaving the ground (6.12 max height COM)
Speed last two steps.. pen..9.46..last..9.54
Horizontal Velocity of CG………8.04 m/s
Vertical Velocity of CG………....2.37 m/s
Resultant Velocity of CG………..8.38 m/s