 Step width variability is positively correlated with rate of metabolic cost, and with respect to the variability associated with mediolateral balance, accounts for about 6% of metabolic cost in preferred gait.While some of the energetic cost encountered with step variability may arise due to the net changes in step width and step length, there exists a portion of the cost that can be attributed to the effort of stability control during walking.Since multiple distinct gait parameters have a significant impact on the energetic cost of walking, each of these parameters have to be considered when examining the primary goal of metabolic cost optimization.