Aikido Center of Jacksonville
Dojo Newsletter January 2009

New Students
Let's welcome our newest students, George, Jonathan, Saimir, and Kevin.  We're thrilled you've joined our school.  Train hard and have fun.

Recent Promotions
Sensei is very happy to announce the following promotions: David, 3rd kyu; Leslie, 3rd kyu; and Christine, 5th kyu.  All three tested at our grand opening seminar with Peter Bernath Shihan.  Your hard work paid off - congratulations. 

Upcoming Seminars
Paul Cobo Sensei of Aikido of Tampa Bay will host Grady Lane Shidoin of Brevard Aikikai on March 14.  Grady Lane will host Robert Zimmerman Shihan of Toronto Aikikai on June 27 and 28.  We'll keep you posted. 

Camping Trip
It's that time of year again:  The birds are chirping, the temperature is dropping.  It can only mean one thing...our annual camping trip.  Let's hope this year no one catches hypothermia.  If you recall, last year we camped at Huguenot Memorial Park.  (You can read all about it in our April 2008 newsletter.)  What could be better?  A blazing campfire, scary ghost stories, and Aikido.  Interested?  You know the drill.

Dojo News
Instructors, please remember to witness the waivers for new students.  It only takes a moment, and is important for school administration.  Domo!

Sensei has also asked that everybody please dispose of their trash after class.  We want to keep the school clean, which is difficult with plastic cups scattered hither and yon.

For those who may not know, Sensei keeps a stash of bottled water and soft drinks in the dojo refrigerator, behind her desk.  All we ask is a small donation, which keeps the goodie bar stocked.  Enjoy!

Lastly, we've finalized the test requirements for our children's class, which you can also find on our class information and multimedia pages.  We spent a fair amount of time organizing the children's kyu ranks, and believe it reflects the priorities Sensei wishes to emphasize to her students.

Fortunately, we had some help.  In particular, we owe a tremendous debt of gratitude to Sue and Steve from Palm Beach Aikikai, who kindly provided their test requirements, which we liberally drew upon.



Grand Opening Seminar with Peter Bernath ShihanGrand Opening Seminar
On Saturday, January 17, we celebrated the grand opening of the Dupont Dojo with Peter Bernath Shihan of Florida Aikikai The seminar was a great success, with students attending from across Florida.  Sensei would especially like to thank the following visiting instructors, whose participation ensured a wonderful experience: Grady Lane Sensei from Brevard Aikikai, Jason Baran Sensei from the UCF Butokukan Club, Sue and Steve from Palm Beach Aikikai, Ted from the Aiki O-Kami Society, and Jim Saba Sensei from Mushin Dojo.

Of course, our warmest gratitude is reserved for Bernath Sensei.  Our students enjoyed the seminar immensely.

New Years Cleansing ClassClass Picture
Keeping with tradition, our January 10 misogi was brutal, but exhilarating.  Rather than talk about cleansing class, (you know, the first rule of Fight Club), we thought we'd show you a few pictures, just to bring back those suppressed memories.Cleansing Class Party
(Of course, Fight Club rules don't apply once cleansing class is over.  Sensei would like to thank everyone who contributed a dish to the potluck dinner.  The flan was especially delicious, as were the meatballs, rice and beans, cheese plate....Heck, it was all good.  Here's to starting the New Year in style.)

Mechanics of the Forward Roll by Ryan Szesny
Editors Note: From time to time we feature student articles in our newsletter.  Ryan Szesny, one of our dedicated students, began his training in April 2008.  In this article Ryan explains the physical principles behind forward ukemi.

Ryan SzesnyAs 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.

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:

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:

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.

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.

Comments?  Questions?  I am sure Ryan would appreciate the feedback.