The Bujinkan* is pretty diverse organization, but as it is a coherent unit there are certain themes that run through the teaching practices. Some of these themes are constructive abstracts that provide tools for learning the art, while others are sloppy constructs that have lost whatever original meaning they possessed and spawn practices that are detrimental to ones martial development. One such practice is the perpetuation of the myth that weight lifting is bad for taijutsu**.
The paraphrased explanation goes something like, ‘It’s good that you don’t lift weights, because lifting weights causes tension in the body and loss of flexibility. Tension will keep you from using your bodies’ natural strength to its full effectiveness.’ That’s it, that’s the whole explanation, and one that I’ve heard multiple times from shihan***.
Now there is a term in there that does deserve some scrutiny as it is specific Bujinkan jargon, tension. Tension is a vague abstract that used as a sort of boogie man for Bujinkan students, and if you attend a class you will hear the instructor invoking relaxation as an anathema to tension. It is the Bujinkan equivalent of the dreaded lurgy.
But what is tension exactly? How is it explained? My take on tension is that tension exists when one is contracting a muscle one didn’t mean to contract, or rather having the habit of contracting the wrong muscles at the wrong time. Not a bad concept, perhaps a bit over-generalized, but it can give a student an idea of where the problem lies and where to pay attention when practicing. Unfortunately, this is not how tension is portrayed. Tension is generally taught as contracting any muscles at all. Some instructors are so into the idea of removing tension that they claim a person can stand without using any muscle tension at all; relying solely on the strength of their tendons to support their weight.
This ‘tension as not contracting muscles’ concept seems to be the culprit behind discouraging weight training. The reasoning once the premise is accepted is pretty straight forward:
1. contracting muscles is bad in principle
2. weight lifting is the practice of contracting muscles
3. weight lifting is bad in principle
While it is true that loss of flexibility can occur due to weight training; it is also true that your car can break down if you don’t your oil. Point being that loss of flexibility can be readily avoided by stretching and moderating how much bulk you choose to gain. In fact, I am probably more flexible since I have started weight training, owing to stretching more often.
What can weight training do for taijutsu? It can reduce tension or at least tension as I define it. Lifting weights, despite seeming a simple exercise, takes a fair amount of concentration and knowledge. It requires that the lifter pay attention and develop good muscular contraction habits in supporting and actuating a load. It requires the lifter to pay attention to balance and skeletal alignment (two other, more positive themes prevalent in the Bujinkan). Assuming the lifter stretches, it will likely indirectly increase flexibility as well.
*The Bujinkan is an organization of samurai and ninja schools head by Masaaki Hatsumi in Noda City, Japan.
**Taijutsu is the specific name of the unarmed combat practiced by the Bujinkan.
***Shihan is a title used to describe members of the Bujinkan that are ranked at or above 10th degree black belt.