The second you initiate movement in your foot you should feel it in your hands. There's no delay. Actually, scratch that, you should always feel "the ground" (in a metaphorical sense) in your hands. As for rooting, that's way too vague. You could direct the force to the ground and simply "brace" with your leg but that isn't it either. In fact you can be "rooted" as you move
This is one of the biggest conceptual hurdles I had to (and still have to, alas) get past in my taiji practice -- caveat: I am a rote beginner -- that the "push" or "whatever you are trying to do" (insert pretty much any example here) happens all at once, with the entire body, when you do it right. That's not to say a movement might not take time, or have a direction to it (usually a spiral in some way) but that it starts all at once, and that filling or connection (what I am guessing Mike means by 'the suit') is there all at once, on or off like a switch. At first I was always collapsing a bit in order to extend instead of filling or expanding up. Those are bad choice of words, I think I mean to say peng
, but that won't help someone either if they have not felt it.
My guess why shiko is so important in some Daito-ryu is you get a similar connection in the body as what I am describing (or failing to adequately describe) above because instead of lifting say the right knee up from the right knee, instead you keep the arch of the legs fixed and draw the right knee up maintaining the arch by pulling across that entire inner leg structure using all the muscles and fascia of the legs and abdomen in the process. This engages the core of the body (psoas complex, etc) including the wedge shaped structure in the pelvis talked about in taiji and yoga to a great extent and links the entire lower half of the body together up into the abdomen, maybe similar to what Su Dongchen says when he admonishes students to "lift up" during single palm change.
Doing even a couple (e.g. 2 or 3) like this wear me out, and I'm pretty sure I'm not doing them right since I haven't had any instruction on this, just read Kimura's book "Discovering Aiki", and thought about how I feel when I do taiji. For me, when I start the leg raise, there is some wobbling of my torso going on as I use a bit of momentum to get the movement started, and then have to stabilize it. I imagine if I were to do it properly over a longer period of time, that wobble would go away as my body got linked together. So, I'm probably obviously missing stuff but it is still a killer exercise when done without much momentum -- and I freely admit am just fooling around with it once in a while when I remember, since I have a bagua and taiji practice to keep up with. Kind of like an ongoing experiment for myself: "does my taiji and bagua practice improve my ability at this shiko exercise over time?"
My current (again, inexpert) feeling is that the shiko drill might be similar in some way to the taiji basic stepping drill of replacing the walking-falling reflex into another way of movement (e.g. separation of weight), except taken in the left right direction instead of the forward back direction. I don't know if Daito-ryu has a consistent theory of separation of weight, such as that found in bagua or taiji. If so, that did not seem to make it fully into the aikido I've seen or the modern aikido/kempo/jujtusu mix I first learned (and spent ten too many years at) before I discovered the internal arts. Separation of weight does not seem to be in the basic Daito-ryu jujutsu waza I've seen from two different lines, so I am guessing even in some Daito-ryu these are more advanced or inner door ideas? Maybe that is precisely why Sagawa and Kodokai are closed groups -- because these ideas are taught earlier than in other lines?
Dan pretty much gives it away when he calls the practice "inyoho" which means "yin/yang practice" -- if that is not a dead giveaway that not just physically by some accident Daito-ryu has similar ideas to neija, but also they frame the mechanism for doing so in the same fundamental language (e.g. yin/yang, insubstantial/substantial), I don't know what is.
My guess is that the shiko (left-right) really works internal development a great deal, while the stepping (front-back) helps with martial development at an earlier stage of the development because it is dealing with a certain way of movement, versus a certain structure that will drive the movement or lack-thereof.
My guess is also that separation of weight is a tactical idea accomplished by certain structural rules in how one holds the body and accomplishes weight transfers. This is very useful for certain reasons, but works best if you support it with certain internal development of the muscles/fascia of the body. But that muscle/fascia development can be done absent of any tactical goal as well?
This post might be slightly off topic, but in terms of how-to put an orange in the box, it might be rephrased as "learn neija or learn daito-ryu". Or, do shiko many times, slowly, without wobbling, and hope that is enough without further guidance.
I mean not to be dismissive with that comment, but rather to be helpful: in some way trying to do internal development exercises by reading written descriptions, for stuff as subtle as internal skill, would be like someone trying to learn aikido waza by reading Aikido and the Dynamic Sphere and copying the line drawing pictures. I had no idea my whole idea of pushing was flawed until I had someone physically correct me to show me how to do it -- even then I only got it five times out of ten as I was rewiring a new movement.
I think it is perfectly fine to go out to people who have specific skills directly and learn from them if for whatever reason the pedagogy you find in your primary art is not ideally suited to an aspect of its curriculum. If you admit that internal development is part of aikido (and you may not -- go back to your regularly scheduled programming), and if you assume it is the same development as Daito-ryu, and if Dan and Mike are correct in saying it is similar or identical to that found in good taiji or good bagua or good xingyi, it is not a betrayal of your love of aikido to go to one of those four arts to focus some of your training and improve your aikido. After all, the Founder had his own development and if Ellis is on the mark in all his blog entries, I don't think he would be disappointed with anyone going out and seeing where it matched up, and improving one's understanding even further.
Not trying to sound like an expert -- many here could probably push me over with a feather -- but maybe this will spur some comments by the people who are in the know.