Is kinesiology part of regular sports medicine, or is it an alternative therapy?

Neither. Kinesiology is the study of human movement not a type of therapy.
Kinesiology. Kinesiology is basically the study of human movement. It is one of many facets that a sports medicine specialist needs to know about.
KINESIOLOGY. Kinesiology is "the study of human movement", and the applications stretch beyond sports (optimizing work environment, and automotive engineering). Sports medicine practices often times have human movement specialist as part of the care team as a means of optimizing sports health, safety and performance. Request a consult via my inbox and we can connect you if interested.
Kinesiology. Kinesiology is the study of how the body moves. Sports med docs get training in kinesiology. There are also kinesiologists, but they are not usually medical doctors.