Maintaining balance in the upright position is a complex motor control task for the central nervous system. Many diseases, injuries or even the normal aging process would affect one or more of these systems thus impairing the body's ability to maintain balance. The body weight support (BWS) approach has been used extensively in ambulation training in patients with Parkinson's disease, spinal cord injury, stroke and total hip arthroplasty, among other clinical conditions. The effect of training on mobility has been demonstrated but the improvement in balance function following BWS training has not been shown significant. The unsatisfactory result may due to the current designs of the BWS systems. A new unweighting system was developed and constructed by Oddsson et al. in 2007 to conduct balance and ambulation training in supine position. In the preliminary study, they found that healthy participants improved on mediolateral control on standing balance after receiving 4 weeks of balance training on the new unweighting system compared to subjects with no balance training. This new promising design seems to be an ideal set up for many patient populations such as strokes, spinal cord injuries, arthoplasty, fracture with surgical repairs, and many others, in order to promote early mobility and balance training. The objective of this project is to duplicate the system that Oddsson et al proposed, and to test the effect of using such a system in subjects with minimal balance dysfunction.