Re: Aikido & Pilates
individual muscle fibers within a muscle can be contracted or relaxed and that will affect overall muscle length. dancers w/ tight quads have shortened quads that pull the pelvis bones in such a way that their butt's stick out. i have opposite: chronically tight hamstrings -- a tendency that conventional stretching does not affect-- that pull the pelvis in the opposite direction and flatten my lumbat curve abnormally, giving rise to low back discomfort.
so, no, bones won't grow or break, but bone position within the body can and does change due to the force of muscles, tendons, etc.