Every time I swing my shinai (by doing any men suburis or doing haya-suburis or anything else), my shoulders get tired and a bit stiff. The only way for not being stiff are only doing any katate wazas (fortunately, I do practice Nito, and it's not a problem).
I'd love to hear any suggestions of helping my shoulders get really relaxed before doing any attacks.
Answers: Hi, Tanno! Thanks for your question! Unfortunately, it is very hard for many to relax because their body does not know how their body should feel like when it is relaxed. Funny, right?
The common and traditional way to let your body know how relax they should be is to train until you cannot lift your arms up even a one millimetre. And from there, by your mind power or determination if you will, execute a strike. That strike will be very weak and useless. And you think it is not even considered to be a good strike. But…
That status of your body is very relaxed. No unnecessary strength anywhere. Your body should remember how your strike felt like when you were really tired.
OK, that is traditional way and very useful and makes you stronger. But here is another way. This is good if you quickly want to know what your shoulders feel like when they are relaxed.
Shrug your shoulders as hard as you can. You can grab your hands really hard too. Basically you create “stiffness” intentionally. Do it for 5 to 10 seconds. Then relax. You can really feel your body has become relaxed.
Remember that and then apply it when you strike. You should replicate the feelings of being relaxed in your shoulders when striking.
Update: How to Keep Your Shoulders Down Video Might Help too.