Central science. There will be a chemistry requirement for entry to training in physical therapy. Chemistry is basic to all of technology and to understanding the body. There will be little chemistry in your practice, but as a health care team member you will be a resource for others seeking accurate information. Chemistry unlocks everything else in science and you must be literate here.
Not so much chem.- -as i would think physics. It involves motion, strength, movement. Muscle contraction is involved in chemistry more, but also physics as it has to do with ions, cell membranes as well as neuro-transmission of commands. There's no simple relationship to one or the other, but I feel more physics..