Mitchel A Magrini, Ryan M Thiele, Ryan J Colquhoun, Alejandra Barrera-Curiel, Taryn S Blackstock, Jason M DeFreitas

There is need for a functional ability test that appropriately assesses the rapid integration of the sensory and motor systems required for older adults to recover from a slip. The purpose of this study was to assess the efficacy and reliability of a novel test, the reactive leg drop, for assessing sensory-motor function in older adults. Fourteen young (YW; mean age = 20yrs) and 11 older women (OW; mean age = 76yrs) participated in this study. For each drop, the leg was passively moved to full extension and then released. The subjects had to recognize their leg was free-falling and reactively kick up as quickly as possible during varying sensory conditions. To assess the leg drop's reliance on proprioception, other proprioceptive tests (e.g. patellar tendon reflexes and balance) were separately performed. Leg drops performed with the eyes closed (p=0.011) and with a blocked view of their leg (p=0.033) showed significant differences in drop angle between the YW and OW. Significant relationships between leg drop conditions and balance were observed in the OW that were not present within YW. When collapsed across groups, reflex latency was correlated with drop angle when the eyes were closed. The reactive leg drop was age sensitive, reliable, and likely reliant on proprioception, as shown by relationships to other sensory-motor assessments, such as balance and the patellar reflex. Although more research is needed, we propose that the reactive leg drop is an effective tool to assess sensory-motor integration in a manner that may mimic fall recovery.