In parallel, the physiological changes the patients experience due to their injury and the wast amount of bed rest and the possible association with the patients' clinical outcome are explored. Training is often limited by orthostatic intolerance. The physiological mechanisms causing orthostatic hypotension and their recovery have not been thoroughly investigated. In other patient populations with neurally mediated syncope or orthostatic hypotension, intensive tilt-table training has been shown to be beneficial. In addition, recent studies including a large number of ABI patients have found an association between impaired cerebral autoregulation measured the first days after injury and an unfavorable outcome.