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« on: April 10, 2012, 06:54:01 pm »
Yeah the one-leg jump is a bit different... it does require strength but it's more of an isometric nature (which is still generated by muscle strength). Still, that's all a muscle "needs to take care of" in a reactive (not voluntary propelled concentrically) one-leg VJ - immediately "lock in isometrically" and then the tendons do the rest (more exactly, the accumulated speed in the run-up does the rest as far as where the energy to go upwards is coming from - you still need the energy to go up there, but you use the energy that already exists in the form of run-up speed and you only need to convert it to vertical torque).
To be honest with you, I don't completely understand the phenomenon. But like Joel Smith said, explosive-isometric is a pretty good term for what happens to the muscles in the one-leg jump - they need to turn on extremely fast and they need to be strong enough to maintain the jumping leg's straight position for the best lever you can get (meaning - to prevent collapse at the ankle, knee or hip).
The thing is - I'm not sure what strength training really does to help this cause. I mean, in a high speed plant the forces on the loaded leg are 8-10x bodyweight. You can't simulate that stuff in the weight room. It's not like you're going to squat or lunge 10x. They also happen in a very short time span (as the amortization phase is very, very short) - so as far as specificity goes... the weight room is far and away from what you need.
Still, a bigger, stronger muscle helps since it should be able to better support the forces in the plant. But if you become accustomed to the eccentric-concentric stuff you usually do in the weight room, and at a slow pace, you can only wonder how that is going to really help specifically in a one-leg jump at a high speed.
I think it's best to work on muscle hypertrophy in the gym for a short while and then pretty much do jumps/sprints that actually use a explosive-isometric regime for your muscles. Bigger muscles + proper "regime" should equal success.