Why do my muscles tend to move away from bone?

Move bones, Not away: I do not understand your question. Except for the muscle cells of the heart & in the walls of arteries, veins & intestines, most muscles are attached to bones via connective tissue structures called tendons (attach muscles to bone) and contract to pull on bones, pulling the tendons/bones at either end toward one another, not away. Please clarify your issue/concern.