Can bending practice lead to diaphragm soreness

Hello harpomarks. I have not heard of this, but it could be caused by it if you're tensing your abdominal muscles while bending. Keep everything relaxed while bending...only tongue movement is required while bending (and you don't need to bring tension into your tongue either). I know it's hard to stay relaxed while doing something new, but try to keep muscle tension to a minimum and remind yourself as you bend that tension is not needed anywhere in your body to bend...it's all about moving to the correct place in your mouth with your tongue (finding that right place is achieved by experimenting over and over as you fine-tune the bending movement for each reed of the harmonica).