Learning To Be Silent

As an engineering exercise, I was recently asked to give my analysis of a forward roll.  Before I begin, however, full disclosure: I am an electrical engineering (EE) student, and make no claim to have any kind of expertise in human anatomy, mechanical systems, or thermodynamics.  However, as part of my education as an EE I have a basic understanding of these subjects.  This particular problem is fairly straightforward, though.

Rigid Bodies, Exchanging Energy

At the outset, please note that the projectile (in this case, your body) is made to be rigid.  Since your body shape does not change, (at least during the roll itself, unless something has gone terribly amiss), and further, since no mass is lost, you possess, according to mechanical theory, a rigid body.  In fact, the rigidity of your body is augmented by your muscles and joint cartilage, which take the brunt of stress during a fall, thereby relieving at least some structural strain.  In mechanical terms, your joints and muscles act as a spring, which are compressed by the impact of falling.

Knowing this, the first step is to define the issue.  In our case, the issue is the interplay between a rigid body and an exchange of energy, or more plainly stated, a forward throw.

Sensei teaches that rolls are meant to be taken close to the ground, to minimize injury.  The principle behind her instruction is sound: the less distance an object travels from its original position, the less potential energy the object contains.  The less energy the object contains, the less severe the jolt your body will receive at the moment of impact.  (This is a good thing).  Since energy can neither be created nor destroyed, the energy escapes from your body into the ground, partly in the form of heat, but also as stress on your legs, since you lowered yourself to take the fall.

The question, however, naturally arises: Why roll at all?  Why not, in fact, fall straight down, if all we’re talking about is transferring energy from one system to another?  Consider figure 1:

Here, the rigid circular body drops straight down.  When force is applied in only one direction, or vector, there is only one point of impact, at the bottom of the circle.  Assume the circle represents uke.  Assume further that the point of impact represents, say, uke’s shoulder.  In the situation described, therefore, the entirety of force represented by the arrow acts upon uke’s shoulder, causing maximum shear stress at that point.  This is not a good thing, and may in fact cause injury.

We roll to transfer energy forward, so that the energy we receive is not just transferred downward, into the mat.  Consider figure 2:

Here, we add a force, in the forward direction.  This forward force creates a moment arm, which causes the body to rotate. 

This rotation causes you to roll, which again is a good thing, since the energy now has a path that doesn’t lead straight down.  (Ouch!)  Essentially, the energy is defused into the forward roll.

This is why we roll.  We use our rotation to transfer energy from an unwanted result, as described in figure 1, to one which allows us to practice another day.  Both scenarios expend the same amount of energy.  The difference is that in the latter, the structural integrity of uke is not tested, potentially to a breaking point.

Standing Tall

We have one more wrinkle to discuss: Returning to our feet.  Remember, a rigid body requires the same amount of energy to fall as it does to return to its former position.  (That pesky law of conservation again.)  The entire process, therefore, is balanced.  Ideally, we as Aikidoka should use that energy, rather than oppose it, to maintain our own balance, on and off the mat.

Before I wrap up, I want to address a misconception I sometimes hear about forward rolls.  It is a fallacy to state that the forward and downward motions described in figure 2 negate each other.  In reality, the energy transferred into the roll is still very much present.  If the vertical force was in fact negated by the horizontal force, then even a perfect sphere, (or the world’s roundest Aikidoka), would not roll.  Rather, the startled fellow would merely slide, on his shoulder in our example.  And yes, this would be a bad thing, since the unlucky Aikidoka could not make use of that rolling motion to transfer his energy into a graceful upright stance, ready to train again.

Editors Note: This article was originally published in the January 2009 edition of our dojo newsletter.

Update: Mechanics of the Forward Roll, Redux

A few weeks ago our dojo had the good fortune to reconnect with a talented Aikidoka from Australia.  He had visited us about four years prior, and was back in the States for, of all things, his honeymoon.  Putting aside any other plans for the evening, our friend attended Sensei’s class, and later taught a very interesting class himself.

That evening, as we caught up at the local watering hole, our conversation turned to (of course!) Aikido.  I had mentioned that Google had some interesting statistics regarding Aikido as a search query. The more I thought about it, the more I realized that this topic deserved its own post.

Google As Gatekeeper

As you probably know, Google is the dominant search engine on the web.  What you may not know is that Google is also an amazing aggregator of information.  Search terms, or in Google parlance “keywords”, are an important way we signal interest online.  If we want to find, say, Thai food in Jacksonville, we search the keywords “Thai food” and “Jacksonville.”  Similarly, if we want to learn about Aikido, we search “Aikido”.  It’s helpful in this context to think of keywords as an electronic vote.

But Google does much more than just match content providers with users.  It also stores this information, in a way that is, at least partially, accessible to us.  The front end for this trove of data is called Google Trends. Go ahead, try it out. I’ll wait.

For our purposes, the significance of Google Trends is this: Over time, the popularity of a search query, such as ”Aikido”, can be a useful barometer of public interest in that subject, or at least that portion of the public with the resources to search the web.

Aikido, Tae Kwon Do, and MMA

So, how does Aikido stack up? Let’s take a look. Although the view we have is fairly limited, the chart does show trends, and in our case, the trend is not pretty.  But is this unique to Aikido?  What about other martial arts, say Tae Kwon Do, or MMA?

First Tae Kwon Do.  Perhaps not surprisingly, Tae Kwon Do, as a traditional martial art, is faring little better than Aikido. (Although its inclusion in the Olympics have resulted in some temporary, albeit impressive, spikes.)

MMA, or mixed martial arts, is a different story altogether. I can’t help but feel a twinge of envy as I look at that rising curve. Whether MMA remains popular, of course, is an open question.

Lastly, out of curiosity, I searched “Steven Seagal”. By my reading, it doesn’t appear that the decline in popularity of “Aikido” as a search query has any real correlation to the popularity of our favorite Aikidoka / actor / musician.

Now the disclaimer: I have no formal training in statistics and lack the background to perform any real analysis of these trends, (even assuming Google made available more granular data.)

Having said that, I do find that these trends back up my own anectodal experience.  Your thoughts?

Oddly enough, starting a new blog is somewhat like shopping for a used car. You check the engine, (are the cherry blossoms the right color?), look for dents, (do I want tags to appear on every page?), and listen for any unusual sounds, (is the search bar the right size?)

Eventually you bite the bullet and pull out your checkbook.

What you see before you is, ahem, our 1974 Porsche 911 Carrera RS.*

Given the pedigree of our former ride, I think it’s fair to say that this blog has something to prove. Whether we succeed, of course, is ultimately up to you, our readers.

First, however, some ground rules. This blog will be about Aikido, in particular, the Aikido practiced at our school, the Aikido Center of Jacksonville. It will be a collaborative effort, with students submitting their own blog posts, on topics of interest to them. You’ll find entries from beginners to more seasoned practitioners. We may even have a guest post on occasion.

And although the posts will be moderated, the opinions you read are solely the opinions of the authors, and do not represent the opinions of either Sensei or the dojo. In fact, we hope that’s the case—it would be a pretty boring blog otherwise.

Capiche? Now if you’ll excuse me, it’s time to crank the engine, roll down the windows, and see what this baby can do.

*You didn’t really expect me to purchase an Accord, did you?