Usually when considering strikes to the body, locations such as bones, internal organs, vital structures, and nerves are thought of as the primary targets for strikes. There can be little doubt that such targets are effective if you find it necessary to use them. But deliberately striking muscles can also be quite effective.
Striking a muscle is not always as straight forward as striking something like a bone or a nerve point. To be effective when striking a muscle requires some degree of knowledge and skill. In one instance a strike of sufficient force may do little damage to a muscle. In another instance the exact same strike placed in the same manner to the same location of the same muscle can do devastating damage. It is important to understand the nature of muscle injuries and how best to strike a muscle when you need to inflict the most damage.
We will study the muscular system in more detail in a future belt, but for now understand that muscles are composed of groups of long fibers that have a strong contracting force. Muscles move, generally speaking, by pulling on something. Often this is a bone, but in many cases (such as facial muscles) a muscle can pull against other tissues. At both ends of a muscle is generally connective tissue, most commonly a tendon that anchors the muscle to the structures against which it will pull. When a muscle contracts it essentially pulls the two connective tissue ends closer together, dragging along any associated structures (often bones). As anyone with large biceps can attest, this contraction process also causes the bulk of the muscle to expand in size and become quite dense.
If you strike a muscle that is in strong contraction you will cause it only superficial damage. The dense nature of the muscle will limit the nature of injury to only the area immediately around the point of impact. This can be painful and can lead to temporary immobility, particularly if you have managed to strike an embedded nerve complex, but the muscle will suffer only localized injury. It is likely the muscle will be capable of normal functionality despite its injury.
If a muscle is in a relaxed state then it is no longer extremely dense and is of minimal diameter. Striking the muscle now, especially if it is a skeletal muscle, will compress the muscle between the strike and the underlying bone, causing damage throughout the entire cross section of the muscle below the point of impact. This is a much more significant muscular injury and may render the muscle incapable of normal functionality. While the muscle is not likely to be completely disabled, its functionality may be substantially degraded.
The trick, of course, is knowing when to strike a muscle so that it is not in contraction at the moment of impact. This is not an easy skill to learn and it requires a good deal of keen observation to understand the required level of timing. We will cover this skill in more detail later, but for now try to get a sense for when specific muscles are likely to be engaged (contracted) and when they are likely to be relaxed. Realize that when one portion of the body is engaged, another part of the body will be relaxed. Also note that when any part of the body is engaged then this is the part of the body that will next be relaxed (retracted). Conversely, the part of the body that is currently in a relaxed state is potentially the next part of the body that will be engaged. We think of this in terms of strength and weakness. Contracted musculature represents strength. Relaxed musculature represents weakness. Attack weakness whenever possible.
Naturally, the muscles you elect to strike can be of some consequence, depending on what you wish to accomplish and how your opponent is (or will be) positioned. Striking the muscles that cause the ear to move may not have a lot of tactical advantage (but it might be quite irritating). Striking a muscle that controls some portion of the arm may be of greater tactical (and strategic) benefit. When you study the muscular system in detail you will better understand which muscles might be potential targets given an opponent’s orientation, structural alignments, and future potential weaknesses.
It is seldom a goal in a conflict to target specific muscles. You never hear anyone say something like, “If I’m ever attacked, I’m going to wait for the Rhomboid major to be relaxed and then I’m going to pulverize it.” So striking muscles is not normally part of a strategic plan (at least initially). It is more often an opportunistic tactical outcome of a dynamic conflict situation. You strike at a muscle because you know it will be relaxed and susceptible to damage at the moment of impact. You do this because you know that action will limit the opponent’s ability to perform some future function. Because that function will be inhibited, you know you will be better able to control and dominate the opponent in the future. This is primarily tactical in nature, though there is some strategic thought involved in limiting future defensive abilities on the part of your opponent.
We discuss muscular striking at this point because we want you to starting thinking in terms of how the body moves and what portions of the body will be relaxed or tense at any moment in time. This will be beneficial in other venues such as in [/glossary]Nage[/glossary], Buki, and Kakutou. Thinking about these issues now will make it easier to deal with more advanced material when it is discussed.
For now, here is an exercise you can work on with a training partner. Have your training partner step forward and deliver an Oi Tsuki and then freeze his or her muscular as it would have been at the moment of impact. Now move around your Uke to see which muscle groups are tense and which are relaxed. Not all muscles on the same side of the body will be in the same state. Understand where there is strength and where there is weakness in the entire body. For this exercise to work it is important that Uke not continually shift or change structural alignments. That will defeat the purpose of this portion of the exercise.
Now have your Uke begin the process of retracting the arm as though they were to initiate a strike with the opposite arm. But have Uke immediately stop their movement as soon as it has been initiated, again freezing the state of his or her musculature. Again feel which portions of the body represent strength and which represent weakness. You should have some sense for this already, but now you will begin to appreciate it at a much deeper level. Appreciate which strong areas have become weak, and which weak areas are now strengthened. Also note any areas that have not changed appreciably. This tells you where you might focus a strike when the opponent delivers and Oi Tsuki. You don’t strike where the Oi Tsuki was strong. Nor do you strike where the Oi Tsuki was weak. You strike where the retraction of the Oi Tsuki will be weak. That is the key to the timing for these strikes.