We are doomed. Repent and ask for forgiveness.

[KirkB]

... the swing is only a redistribution of the energy built in the run up ...

RPVA03, I agree with everything you said. I think you've nailed it, IMHO.

Just one slight clarification, which I alluded to in a recent post where I said that takeoff speed is all that really, really matters ...

The runup determines your speed the msec before takeoff. Depending on the efficiency of your takeoff, your takeoff speed might be more or less than your runup speed. So what really, really counts is only your takeoff speed.

In other words, you can have a fast run and then brake on takeoff ... or you can have a slow run, and then a tremendous, accelerating jump on takeoff. It's only the speed at the point of takeoff (i.e. the msec after takeoff) that really, really matters.

This also takes into account inertia. So obviously, if you have lots of inertia from a fast runup, plus lots of jumping force on takeoff, the net of those two would result in a very good takeoff speed.

It would be almost impossible to lose ALL of your inertia on your takeoff, no matter how hard you put the brakes on. Thus, your runup speed is accounted for in my takeoff speed formula.

But it's not JUST runup speed. It's:

RUNUP_SPEED + JUMPING_FORCE = TAKEOFF_SPEED.

JUMPING_FORCE can be either negative or positive - or neutral.

I would like to elaborate futher on this, to include the ANGLE of this force, but unfortunately, nobody has accurate data. I've heard it said to be as high as 45°, and I've heard as low as 16-18° (Dick Railsback). I have no idea what's ideal, or what's reality. I think my best jumps were on the lower end of this spectrum, but I can't quantify it - nor did I ever I consider my jumping angle optimal.

Again, this is only IMHO. It's subject to any criticism or clarification you may have.

Kirk Bryde

[agapit]

... the swing is only a redistribution of the energy built in the run up ...

But it's not JUST runup speed. It's:

RUNUP_SPEED + JUMPING_FORCE = TAKEOFF_SPEED.

I would say that RUNUP_SPEED - LOSES OF SPEED AT THE TAKEOF = TAKEOFF_SPEED

You cannot really add speed and force they are apples and oranges.

You have a very good point. To have a better takeoff, the takeoff foot should move fast (the faster the better), hence the advantage of acceleration or increase in cadence that results in faster (shorter) reaction of the takeoff foot with the ground. This indeed leads to lower speed loses while generating a larger vertical takeoff speed component and faster swing of the takeoff leg.

[KirkB]

Yeh, I didn't really mean FORCE.

Let me amend that to:

RUNUP_SPEED + JUMPING_SPEED = TAKEOFF_SPEED

I think the rest holds true. And yes, JUMPING_SPEED is most often a negative value - but on a short-run vault, maybe not.

The shorter the run, the more likelihood that you'll be accelerating off the takeoff foot (because of lack of speed from the runup). No?

Kirk Bryde

[agapit]

Yeh, I didn't really mean FORCE.

Let me amend that to:

RUNUP_SPEED + JUMPING_SPEED = TAKEOFF_SPEED

I think the rest holds true. And yes, JUMPING_SPEED is most often a negative value - but on a short-run vault, maybe not.

The shorter the run, the more likelihood that you'll be accelerating off the takeoff foot (because of lack of speed from the runup). No?

Kirk Bryde

I am sorry to tell you, but unless you are jumpping without run up the jump is always a negative value for the total speed.

No chaff here only wheat!

[volteur]

Agapit

in support of your manifesto i can confidently say that it is one of the clearest and most precise explanations of an event i have ever seen. It is up there with the explanations from Lydiard and Cerutty in the middle distance world. Congratulations for understanding your craft so damn well, and thanks a lot for increasing my own clarity.

Volteur

[agapit]

Agapit

in support of your manifesto i can confidently say that it is one of the clearest and most precise explanations of an event i have ever seen. It is up there with the explanations from Lydiard and Cerutty in the middle distance world. Congratulations for understanding your craft so damn well, and thanks a lot for increasing my own clarity.

Volteur

I know it may sound like a cliché, but I see myself as one link in the long chain of people that came before me. We are all standing on their shoulders and hopefully our shoulders will be a soling support for people after us.

Thank you for your support anyway!

[KirkB]

I am sorry to tell you, but unless you are jumpping without run up the jump is always a negative value for the total speed.

No chaff here only wheat!

I'll buy that. I don't have any scientific proof either way, but it's plausible that acceleration on takeoff is idealistic - not to be taken literally.

So when your coach says "accelerate on takeoff", he doesn't really expect that you can, he just wants you to strive for that. What he really means is "Try to decelerate as little as possible".

It's actually kinda despressing, when you think of it.

Or a more encouraging way to say that would be "try to maintain all of your runway speed, shorten the last step, claw the takeoff, and jump like hell!"

Kirk Bryde

[volteur]

Agapit,

i am having trouble with this bit as off a 2 step jump i can feel myself accelerate through the takeoff. Is this an illusion in some way?

[golfdane]

Or a more encouraging way to say that would be "try to maintain all of your runway speed, shorten the last step, claw the takeoff, and jump like hell!"

Kirk Bryde

I would say, shorten the last 2 steps, but YEAH!!!

[agapit]

Agapit,

i am having trouble with this bit as off a 2 step jump i can feel myself accelerate through the takeoff. Is this an illusion in some way?

I am not aware of the 2 step studies, but my guess would be that even from 2 steps you would loose speed on the jump.

[volteur]

Agapit,

i am having trouble with this bit as off a 2 step jump i can feel myself accelerate through the takeoff. Is this an illusion in some way?

I am not aware of the 2 step studies, but my guess would be that even from 2 steps you would lose speed on the jump.

I'm not aware of any 2 step studies either but i do know i accelerate through the jump from sub-maximal runups. Hurdles is the most extreme as i definitely accelerate across the first hurdle after an 8 step run-in. Of course if i put too much vertical lift at takeoff then i lose horizontal speed but vault takeoff is more about running off than jumping is it not?

[powerplant42]

So when your coach says "accelerate on takeoff", he doesn't really expect that you can, he just wants you to strive for that. What he really means is "Try to decelerate as little as possible".

Fixed that one for ya.

To me, the sensical conclusion is that if you are running as fast as you can, it is more or less impossible to accelerate in your actual jump... One must consider what is occurring during the take-off: the hips drop during penultimate and are being lifted up during the take-off step...work that WAS being used for running is now being used for beginning the jump, the drive knee begins an unnatural sprinting movement (slowing speed), and there is no longer any focus on going forward, instead, the focus is shifted to moving upward, AGAINST GRAVITY. This is the main key... velocity is changed in its direction relative to a restricting force. Are there any studies out there on this?

--Also, let me just throw out there that this loss of velocity is minimized by a free take-off.