This study investigated how newly walking toddlers with Down syndrome (DS), after different treadmill interventions, adopted clearance strategies and modified anticipatory locomotor adjustment patterns to negotiate an obstacle in their travel path. Thirty infants with DS (about 10 months of age) were recruited and randomly assigned to either a lower-intensity, generalized (LG) treadmill training group, or a higher-intensity, individualized (HI) treadmill training group. Thirteen in each group completed a one-year-gait follow-up after the treadmill intervention. Initially, both groups chose to either crawl or walk over an obstacle. However, walking over the obstacle became their preferred clearance strategy over the course of the gait follow-up even though the height of the obstacle increased from visit to visit. The HI group used the strategy of walking over the obstacle at a considerably higher percentage than the LG group within 6 months after the training. When approaching the obstacle, both groups started to show consistent anticipatory locomotor adjustments about 6 months after the training. Both groups decreased velocity, cadence and step length, and increased step width at the last three pre-obstacle steps. It was concluded that the retention of the HI training effects led the HI group to predominantly walk over an obstacle earlier than the LG group within 6 months after treadmill intervention, and the two groups produced similar anticipatory locomotor adjustments in the last three steps before negotiating the obstacle.