Re: fear of ukemi
I would like to say that in my opinion weight has very little relevance. On the contrary for big people like me it is kinda easier to keep thr roll shape during Ukemi.
When I started Aikido I had problems with front Ukemi. My shoulders would kill me. With time I have learnt to take Ukemi a little better and passed the problem. Yes, most of the time if the shoulder hurts during Ukemi is because the shoulder is taking most of the hit from the fall.
In my case the problem was that I was not doing long enough Ukemi, but kinda falling down at my feet. Visionizing a more long stretched Ukemi helped me alot to solve the problem.
But if you have problems with your shoulders you should limit your training. I recently injured my shoulder and noticed that certain things are a real "shoulder murderer" to do. In my case the worst of all is Ikkyo or a real sharp Shihonage.
Try to notice what bothers you and ask kindly your Sensei to spare you from doing it.
Oh one last thing...shoulders damage can take a very long time to heal. For me it has been over 5 months now and still fighting against it.