Two experiments were designed to explore how age differences in conflict detection may contribute to poorer motor performance. In each experiment, 12 young adults (YAs) and 12 older adults (OAs) performed a finger sequencing task in which the frequency of specific critical transitions was varied. These critical transitions were contrasted with violation transitions to assess the ability to detect a conflict in response requirements. In addition to accuracy and reaction time, the authors used kinematic data to parse movements into planning and motor execution phases. OAs were differentially slower to respond to violations than YAs, in line with other research on executive control, prepotent response suppression, and aging. Kinematic analyses revealed that YAs executed movements more rapidly on violation than critical transitions, whereas OAs executed movements at the same speed regardless of response predictability and increased planning time. The authors argue that OAs are unable to reprogram prepotent movement plans to overcome slowed movement planning in cognitively challenging situations. The results are discussed in terms of the influence of age-related cognitive inefficiency on motor control.