It's interesting because whenever I have the foot away from the body I have the tendency to bend forward at the waist a lot so I can move the center of gravity forward and reach to my quads to initiate the movement, and do a good morning out of there as well (using more spinal erectors than glutes to do it).
Another interesting thing I discovered is that I tried to do a step-up using a low bar placement on the back, and I couldn't do it. Like, literally. I couldn't even step on the "box" (3 or 4 plates actually)... I just couldn't imagine myself going up with that bar placement. That was really a WEIRD thing... and I wasn't even using a lot of weight. It happened using a 70-80 kg bar.
It sounds like youre trying to let the pelvis shift back to get the low/back and quads into it more, which is what happens w/ bounds and sprints as well in many athletes. Being able to keep the pelvis in a neutral position while you apply force is by far a more optimal position for sprinting, single leg jumping, and bounding, but it takes some re programming in some cases. I would say do some bounds and focus on staying tall, and only jumping as high as youre able to while keeping the pelvis in a good position. Do the same with the single leg box squats. It shouldnt take long for you to adjust once you start really focusing on it, and you will notice much better movement effeciency and power with bounds and jumps.
Yeah that's exactly what's going on I guess. It feels like that in maximal one-leg jumps too. I push my hips back AND down quite a bit and I feel the upperbody kind of going forward, but because I plant the jump leg so far away forward kind of compensates the upperbody bending forward and it looks like I have a straight upperbody position to the ground.
But it doesn't feel/don't know how to do it otherwise. I don't know what you mean by "pelvis neutral position" either. I mean, the hip joint is going to lower or raise or displace in some way no matter what, so... not sure exactly what you mean
The first thing to do is pay attention to your bounding, neutral is pelvis not kicked back, not pushed too far forward, where optimal firing patterns can occur. There will be a height/speed for almost everyone where you can no longer maintain that position, once you find it, you work at an intensity just below that. Little cues to let you know when youre no longer in an optimal position is a.) leaning forward with the torso, b.) kicking the hips too far back or over arching. You will see this happen on exercises like rdl's as well, once the load is heavy enough some athletes will over arch the back. Basically, if the hips are not very close to directly under the torso, youre out of position. Thats the whole big deal with the "penultimate, super jump magic technique, extreme gains, etc.", all the coaches are trying to convey is keeping good pelvic alignment for optimal jumping power. Every time you bound think, stay tall, hips high and directly underneath the torso. Repeat those mental cues to yourself, watch it on video, and youre on way to a better bound and single leg jump patterning at higher takeoff speeds.