During critical illness, patients who are immobilized for more than a few days develop severe muscle and nerve weakness despite receiving full supportive care, which may include physical therapy. In patients requiring mechanical ventilation (a device that breaths for them) for longer than 7 days, the incidence of ICU-acquired weakness is reported to be between 25% and 60%. Such weakness may contribute to increased duration of mechanical ventilation, increased length of stay in the ICU and hospital, and poor quality of life among survivors. This is part of the newly recognized Post Intensive Care Syndrome (PICS). Moreover, patients who are transferred from the ICU to a high-dependency unit (HDU), intensive therapy unit (ITU), post-operative therapy or outpatient ambulatory care need to be mobile as well as awake for any physical therapy. Patients affected by sepsis (severe blood stream infections), osteoarthritis, spinal cord injury, stroke, multiple sclerosis, cerebral palsy, cancer, and other illnesses suffer muscle loss and weakness. Early mobilization (EM) has demonstrated the ability to significantly reduce the detrimental effects of prolonged immobilization such as polyneuropathy and myopathy (nerve damage and muscle weakness), which in turn reduces the time patients spend on mechanical ventilation and the overall length of hospital stay. EM treatments include intense physical therapy, cycle ergometry, transcutaneous electrical muscle stimulation (TEMS) and continuous lateral rotational therapy (CLRT). However, carrying out intense physical therapy using therapists is impractical (especially at smaller hospitals) and cannot be implemented in heavily sedated patients (patients who cannot cooperate). Evidence suggests that vibration may be capable of producing adequate muscle contraction via muscle-spinal loops that may be sufficient to reduce or prevent nerve damage and muscle weakness caused by prolonged immobilization thus serving as an effective treatment making patients stronger when they leave the ICU.

The purpose of this study is to test a prototype vibration device and strategy on its ability to exercise large muscle groups, increase muscle blood flow, and increase circulating levels of blood chemicals associated with exercise/activity. The study will be used to find optimal vibration frequencies that provide maximal evidence of associated muscle activity. Eventually the investigators hope to see a vibration device capable of delivering a more effective therapy compared to the smaller gains derived from traditional measures of physical therapy in critically ill patients such as TEMS, CLRT and cycle ergometry to patients. The vibration device may directly benefit the patient in terms of health, length of stay and reduced re-admission, hospital staff in terms of productivity (i.e., through reduction in nursing effort) and the hospital in terms of reduced cost and return on investment. Its value is also envisioned in many other populations of immobilized acutely ill and injured patients as well as those with chronic conditions.

Originally registered as a single record, this registration has been simplified to clarify the outcomes measured from the work with healthy volunteers. A new registration which will include the relevant outcomes for the trial part that will enroll hospitalized participants will be registered prior to their enrollment. The current registration will remain open until it is certain that no additional modifications of the device are required to go through a new round of iterative testing with healthy volunteers. While the total number of participants to be enrolled is larger than some early feasibility trials, the testing is done in small iterative batches to determine whether additional design changes are required. Each of these is generally less than 10 individuals.