Sixty subjects will be randomly assigned into either TC instruction or VR. Both treatment groups will receive identical duration treatment once a week for 10 weeks, with supplemental home exercises. It is hypothesized that 1) TC improves whole-body dynamic locomotor stability more than does VR; 2) TC improves gait coordination during planned and unplanned obstacle encounters more than does VR; 3) TC improves whole-body speed related movement control more than does VR.