A few days ago, I got an email from one of the students in my email coaching program, and I thought it was worth sharing.

I've got a question about this week's Taido tip, you mentioned that the back should be straight during ebi geri. Why is this, what is the advantage (other than bringing your head in to safety)? I always have it bent because otherwise I'm not able to see my opponent.
Here was my reply:
Good question with lots of good answers. Mechanically, a straight line from head to heel means that the force of the kick transfers more directly into the target. Experiment: slowly kick a wall with ebigeri that way you normally do, and see where your body absorbs once your foot touches the wall. This is the weakest link in your kick, and I bet it's your lower back. Keeping your back straight means that the force of the kick has only two places it can be released - the target or the floor, through your arms. Since your hips should be moving toward the target, momentum favors the force going that way. From the perspective of building good habits, straightening your back will require you to bend your stationary knee further, which is good for balance and stability. The knee also helps you gauge how straight you are; if the knee is bent, you can tell how far it has turned, but this is more difficult if the knee straightens while turning. I don't know why, but that's just the way those mechanoreceptors work. As for looking... are you fucking kidding me? If your ebigeri is so slow that you have to watch while you're kicking, you're not going to hit anything anyway. Here's the funny thing though: looking at your kick will actually decrease your accuracy. The simple truth is that your brain doesn't process an upside-down world very well and has a hard time adjusting to what you see. You're far better off to look at the floor and focus on lengthening your spine. Aim before you kick. Aim where the target is about to be. Kick fast. Of course, that means that line and target training are all the more important. Lots of people look at their kick in ebi, but that doesn't make it ideal. Proper body mechanics are the highest law of technique.
Followup from the student:
Thanks for the answers! By the way, right now I don´t look for aiming purposes; I look to see my opponent. If he does kosuku for instance, that means that I have to get up at a different angle so that I immediately face my opponent - or he will be at my flank. Or is speed again the answer, kicking and getting back up and doing so faster than the opponent can do a kosuku...?
My reply:
I see where you're coming from. Consider the fact that nobody throws ebi as an attack in jissen. There's a good reason. It doesn't work very well, and this is part of the reason. Ebi is a straight line technique that Shukumine created for defending against a charging opponent in a confined space. When unsoku isn't an option, ebi is a good defense, but it's not really viable as offense (you're turning a portion of your momentum away from the target after all). In some ways, yes, speed is a factor in what you describe. A fast ebi really shouldn't give the opponent much time to move. Beyond that, you should get in the habit of executing techniques that are directed where the opponent is heading to, not where he already is. This means attacking within the flow of unsoku instead of after a step is complete. One of the many benefits being that, if you know where he's about to be, you don't necessarily have so see him all the time (though seeing is good - it's not not required for the entire movement).
The reason I wanted to share this is because, as I wrote above, a LOT of people do ebi this way, while looking at the kick. I want to emphasize that, in 99 cases out of a hundred, I really do recommend keeping your eye “on the ball” while kicking. It’s just a good idea in general, but every rule has exceptions, and this is one of them. The main point here is about mechanics. Good mechanics are what makes any technique work. Taido is perhaps most accurately translated into English as the art of the body. It only makes sense that we way he use our bodies is going to have a big impact on how well we are able to perform Taido. What's less obvious is that there are at least two levels on which this is true: the mechanics of the technical (punching and kicking) movements and the overall mechanics of human physiology. Good technique requires that both be sound.

Technical Mechanics

Technical mechanics are spelled out in Taido Gairon, specifically the chapter on doko, which appropriately could be translated as "how to move." This includes the doko5kai - five principles of mechanics for each of the basic techniques (which I've outlined here: sentai, untai, hentai, nentai, and tentai). The technical mechanics are unique to Taido and differ from one technique to the next. Furthermore, their execution may differ among techniques even of the same general class. For example, the instruction kihatsu seisoku for ungi suggests that the be careful with your rear (kicking or lifting) leg so the opponent can't stop your technique. This applies to all ungi, but its application will take different forms in standing techniques versus jumping technique.

General Mechanics

By general body mechanics, I'm referring to the natural structure and movement of the human body. We can call it physiology, biomehcanics, or really any number of things, but the point is that the body is built in a certain way that favors certain types of movements and positions over others. There are limits to how we can move without injuring ourselves. There are also ways to move that produce greater force than others. I'm oversimplifying, but you get the picture. General mechanics are not very thoroughly spelled out in Taido texts, possibly because they are universal. However, being universal doesn't mean that most people practicing Taido understand or demonstrate them well. For example, though we all know that posture is important, few of us have consistently good posture. But good mechanics go far beyond good posture and extend to correct alignment and use of all our joints. It takes practice, and that's the trouble: when we practice Taido, we want to practice techniques, hokei, and jissen - not some kind of abstract poise, or use (as the Alexander folks call it). So we tend to ignore, or at least gloss over, the issues of body mechanics in our practice, because we want to prioritize our training time for Taido. And that's really OK for rainbow belts. Taido is complex, with a lot of movements and ideas to internalize. But then we have to work even harder to relearn everything with good mechanics later.

Back to Ebigeri

Anyway, to return to the original discussion, check out this video from the finals of the 2009 World Taido Championships. Nakano and Pylvainen both have fantastic body mechanics all around, but specifically pay attention to how straight their backs are when they kick tentai ebigeri after the first kiai - direct line from head to heel.

That's what we should all strive to look like when performing this kick.