Human standing balance is a complex of systems, like the muscles, nervous system and sensory systems, interacting with each other in a closed loop to maintain upright stance. With age, disease and medication use these systems deteriorate, which could result in impaired balance. In this paper, it is demonstrated that multi-input-multi-output closed loop system identification techniques (MIMO-CLSIT) can be used to assess the underlying systems involved in standing balance and guide possible therapeutic options. In this study, mechanical and sensory perturbations were combined and applied simultaneously using a Balance test Room. The results demonstrate the value of MIMO-CLSIT to assess the underlying systems involved in standing balance and therefore to improve diagnosis of impaired standing balance.