Abstract: Tissue force displacement data can be used to evaluate the suitability of a subject for an apnea therapy, such as therapy with an implanted magnet. A method of evaluating a suitability of a subject for an apnea therapy comprises placing an engagement structure on a tissue of the subject to engage the tissue of the subject. The engagement structure is moved toward the tissue to a location to move the tissue. One or more of the location or a force to the engagement structure at the location is measured. The suitability of the of the subject for the apnea therapy is determined in response to the force at the location.