Archimedes once said something to the effect of, "Give me a lever long enough and a fulcrum and I will move the world." So many variations out there, but I wasn't there so I won't challenge anyone else's version.
A lever is a stick. By coincidence, so is a Jo.
When I started to work on Jodori and Jonage, I started to pay attention to mechanical advantage, or the benefit of leverage.
There are three types of levers. With a Jo, we get to pick a fulcrum ( the still point that the Jo rotates around) and we can change the fulcrum easily, even in mid-swing.
A class 2 level provides the greatest mechanical advantage. An example of this type of lever is a pry bar. The end that Uke holds is the end left in place, and Nage can move around that point. The fulcrum is at the end held by Uke. It happens to be the principle of katate dori tenkan done at the start of every class. Nage allows Uke the part of the Jo that is grabbed, and relocates and finds a new angle to push from. A number of Aikido finishing pins like the standing Kotegaeshi pin use this type of leverage.
A class 1 lever has less mechanical advantage than a class 2. An example of this type of lever is a teeter totter. The middle of the Jo is the fulcrum. This movement is easily applied to a Jo - the forward hand becomes the fulcrum. Ikkyo typically uses this type of leverage. A circling motion is easy to do, even when Nage is not able to step much. This type of leverage is used in continuous nagare motions too.
A class 3 lever offers the least mechanical advantage. An example would be a fishing rod. One of my wife's favorite techniques uses this type of leverage, but I don't know the name of it. It is a type of higikime. The fulcrum is close to your body and still while you affect Uke through the elbow.
I found this interesting to play with in Jodori and Jonage. Which lever does the technique make use of, and at which point? And, which lever am I actually doing? What is my mechanical advantage, how and when do I use it, and how do I improve on it?
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