The aim of this study was to examine the influence of Assisted Cycling Therapy (ACT) on information processing measured by simple reaction time in older adults with Down Syndrome (DS). Twenty-one participants were randomly assigned to one of three interventions over eight weeks. 1) Eleven older adults with Down Syndrome completed the ACT intervention, which is stationary cycling with the assistance of a motor to maintain a cadence at least 35% greater than voluntary cycling. 2) Eight older adults with Down Syndrome completed the voluntary cycling (VC) intervention and 3) two older adults with Down Syndrome were in our no cycling (NC) intervention. Both exercise groups participated in the eight-week, supervised exercise protocol for at least three, 30-minute sessions per week. None of our results reached conventional levels of significance. However, the greatest improvements in reaction time occurred following the voluntary cycling (VC) intervention. Our results are discussed with respect to physiological differences in older adults with DS that may limit improvements in executive function following exercise. These physiological differences and limitations include muscle atrophy and reduced perceptions, age related latency between motor cortex activation and onset of muscle activity, as well as general age related slowing in reaction time. Although it may be difficult to improve executive function in older adults with DS, we suggest other benefits to exercise which include improving social communication, gross motor skills, and exercise perception. Future research should continue to investigate the effects of exercise on multiple areas in older adults with DS with the hopes of improving quality of life.