The power of standing up

Studies show that body-fixed motion sensors can be used for long-term monitoring of sit-to-stand (STS) performance in older persons. However, it is unclear how sensor-based measures of STS performance relate to functional status in older adults. Therefore, this study investigated the associations between sensor-based STS measures and standard clinical measures of functional status in older adults. Participants (24 females, 12 males; 72-94 years) performed five normal STS movements while wearing motion sensors on the hip and chest. Objective measures were used to assess mobility (Timed-Up-and-Go test, Five-TimesSit-to-Stand test, Stair Walk test) and quadriceps strength. Self-reported questionnaires were used to assess limitations in activities of daily living (Groningen Activity Restriction Scale) and frailty (Groningen Frailty Indicator). In general, chest STS measures showed a larger number of significant associations and stronger associations with clinical measures than hip STS measures. Chest maximal velocity, chest peak power, chest scaled peak power and chest stabilization phase SD demonstrated significant associations (weak to strong) with all six clinical measures. Noteworthy is that hip stabilization phase SD showed significant associations (weak to moderate) with five clinical measures. In particular chest peak power and chest scaled peak power demonstrated a moderate ability to discriminate between higher and lower functioning individuals (area under the receiver operating characteristic curve: 0.75-0.90). This study shows that in particular chest STS measures are indicative of objective and self-reported aspects of functional status in older adults. These findings support the clinical relevance of sensor-based monitoring of STS performance in older persons.