Sounds like biomechanics would involve all sorts of physical applications to medicine, like in orthopedics, tissue growth, etc. Typical classes might involve statics, deformable body mechanics, numerical methods, finite element modeling...Its hard to know if you'd enjoy that stuff before "testing it out". Maybe you could shadow a current student or wikipedia some of the topics i mentioned.
As a biomedical engineering major, i know that biomechanics was an optional branch of my major, along with bioelectricity, cell & tissue, biomaterials, etc.