In some cases, an ailment may affect a patient's activity level or range of activities by preventing the patient from being active. For example, chronic pain may cause a patient to avoid particular physical activities, or physical activity in general, where such activities increase the pain experienced by the patient. Other ailments that may affect patient activity include movement disorders such as tremor, Parkinson's disease, multiple sclerosis, epilepsy, or spasticity, which may result in irregular movement or activity, other neurological disorders, or a generally decreased level of activity. The difficulty walking or otherwise moving experienced by patients with movement disorders may cause such patients to avoid movement to the extent possible. Further, depression or other psychological disorders such as depression, mania, bipolar disorder, or obsessive-compulsive disorder, congestive heart failure, cardiac arrhythmia, gastrointestinal disorders, and incontinence are other examples of disorders that may generally cause a patient to be less active. When a patient is inactive, he may be more likely to be recumbent, i.e., lying down, or sitting, and may change postures less frequently.
In some cases, these ailments are treated via a medical device, such as an implantable medical device (IMD). For example, patients may receive an implantable neurostimulator or drug delivery device to treat chronic pain, a movement disorder, or a psychological disorder. Congestive heart failure and arrhythmia may be treated by, for example, a cardiac pacemaker or drug delivery device.