Balance is a stability to maintain postural control as an in- and output from visual, vestibular, and somatosensory systems. Therefore, balance testing is very important part of tests in human performance. Balance is an ability to maintain body in control with minimal body sway (line of gravity within their base of support), in which all acting forces are cancelled by each other resulting in a stable and balanced posture.
The control of body sway is a result from co-operation between multimodal systems. The central nervous system (CNS = Brain and spinal cord) receives information and controls the body orientation from three main sensory systems (somatosensory, vestibular and visual systems). Body sway is an integration of this sensory feedback and subsequently generating a corrective outcome, stabilizing body by selectively activating muscles. Therefore, balance evaluation is a key to our CNS and it is an important part of neurological tests.