Getting up and sitting down from a chair are basic prerequisites for maintaining independence during daily activities. Although the Sit-to-Stand (STS) movement is performed numerous times a day without paying attention to it, it turns out to be a challenging gesture for more categories of people, with special reference to the frail elderly. This movement becomes essential to avoid further impairment of their motor skills as they age. In fact, the STS is used within some patient assessment tests and as a rehabilitation and conditioning tool. For patient assessment, there are multiple variants of the Sit-to-Stand Test (STST), each of which aims to measure the patient’s different motor and metabolic abilities; some studies have shown that the integration of simple electronic devices to the STST can provide diagnostically and evaluatively important objective data. In this article we describe the usefulness of STST in reeducation and rehabilitation and the potential of instrumental Sit-to-Stand Test (iSTST) in diagnosing frailty condition in the elderly.