powerplant42 wrote:Well, you can't really 'decide' to leave the trampoline, but you can decide to let go... But I know what you're saying.
Irrelevant.
But I do agree that we should choose our words carefully, and I'm afraid that I have to clarify what I meant by "FASTER".
Of course you should drive FASTER than the recoil of the pole. Otherwise, you're just "riding" it. Extending FASTER than the pole is what adds energy to the system.
I retract this statement - it's misleading. What I meant to say is that the NET EFFECT of extending in unison with the pole is that the ENTIRE SYSTEM (the pole + the athlete) moves FASTER.
Let's break this down. On the pole, when you extend (or not), only one of 3 things can happen:
(1) Your body stays rigid - no active extension, yet no energy leakage. i.e. You're riding the pole.
(2) Your body goes a bit limp - sufficient to cause leakage to the system. i.e. As the pole is recoiling, you (a) tuck [too late] or (b) row or (c) drop your shoulders or (d) have some other "leakage" flaw or (e) do a combination of these flaws.
(3) Your body actively extends - adding energy to the system. i.e. You're using the rigid body + the "continuous chain" theories to extend higher.
Compare this to jumping on a tramp.
(1) If you land rigid, then you'll bounce back up to approximately the same height. Of course that's difficult to simulate, because even if your body is stiff, there's other factors that cause leakage - such as friction in the springs and elastic parts of the tramp. But you get the idea. In theory, you don't add any energy, nor do you lose any.
(2) If you (a) let your arms go limp as you land and rebound on the next jump or (b) absorb some of the shock of landing with your knees or torso (i.e. your body isn't stiff), then you're leaking energy from the system (the tramp + athlete).
(3) If you swing your arms going up as you jump up with your knees and ankles - in unison with the recoil of the tramp - then you're adding energy to the system.
Notice that on the tramp and on the pole, it doesn't actually matter how FAST you actively extend your body. Even the slightest bit of active extension is sufficient to add energy to the system, which will result in a positive outcome.
Now, having said that, it is true that the faster you extend your body (whilst the more efficiently you prevent leakage), the higher you'll bounce on the tramp or extend on the pole. But the relative speeds of recoil and body extension are irrelevent.
Also, Powerplant42, to clarify one other misunderstanding, I think you might have taken my term "
in unison with the pole" to mean "
ride the pole with no additional energy added". That's definitely not what I meant. You may have taken that meaning by thinking about the "
common distance covered by the pole and the body" instead of the "
common time span covered by the pole and the body". Clearly, I'm referring to the latter.
I hope that's clearer now.
One last point ...
The time span that has the most affect on the outcome is the time
immediately after the recoil. Again, this is true of both the pole and the tramp systems.
Think of it this way: Separate your tramp bounce into 3 parts. The first part is as the springs and elastic on the tramp are stretching. The second part is the first half of the time it takes from the lowest position of the jump to when your toes leave the mat. The third part is the second half of the jump.
When you bounce on the tramp, you your objective in part 1 should be to stay as stiff as you can - to minimize leakage (energy loss). Your objective in part 2 should be to jump as vigorously as you can. Your objective in part 3 should be to extend your jump fully off your toes, with straight body, as quickly as you can.
Now imagine what would happen if you tried to apply LESS pressure during part 2, then tried to apply MORE pressure in part 3. It's too late, isn't it?
Same thing on the pole!
I'll give you another good anaology - clean-and-jerk. If you pull up slowly at first, then try to pull up faster, you won't lift as much weight. You must pull as hard as you can immediately off the floor - then just finish pulling as you bring the bar to your shoulders. In my experience, the clean-and-jerk motion is so close to the extension that I extended (my torso, especially) on the pole very much like I was doing a clean-and-jerk!
The first half of your extension is much more critical than the second half!!!
Got it?
Kirk
) But discussion is always good. I will comment more later, but for now I see this as 'redirecting' energy, not adding it, but it occurs while energy is being added... perhaps it is adding energy? I'll keep my mouth shut for now and read what others have to say, and then I'll give it my best shot.
